Search results for: bending modulus

Authors: K. Jankowski, M. Pawlikowski, A. Makuch, K. Skalski

Abstract:

Depth-sensing indentation (DSI) or nanoindentation is becoming a more and more popular method of measuring mechanical properties of various materials and tissues at a micro-scale. This technique allows measurements without complicated sample preparation procedures which makes this method very useful. As a result of measurement force and displacement of the intender are obtained. It is also possible to determine three measures of hardness i.e. Martens hardness (HM), nanohardness (HIT), Vickers hardness (HV) and Young modulus EIT. In this work trabecular bone mechanical properties were investigated. The bone samples were harvested from human femoral heads during hip replacement surgery. Patients were of different age, sexes and stages of tissue degeneration caused by osteoarthritis. The specimens were divided into three groups. Each group contained samples harvested from patients of different range of age. All samples were investigated with the same measurement conditions. The maximum load was Pmax=500 mN and the loading rate was 500 mN/min. The tests were held without hold at the peak force. The tests were conducted with indenter Vickers tip and spherical tip of the diameter 0.2 mm. Each trabecular bone sample was tested 7 times in a close area of the same trabecula. The measured loading P as a function of indentation depth allowed to obtain hysteresis loop and HM, HIT, HV, EIT. Results for arbitrarily chosen sample are HM=289.95 ± 42.31 MPa, HIT=430.75 ± 45.37 MPa, HV=40.66 ± 4.28 Vickers, EIT=7.37 ± 1.84 GPa for Vickers tip and HM=115.19 ± 15.03 MPa, HIT=165.80 ± 19.30 MPa, HV=16.90 ± 1.97 Vickers, EIT=5.30 ± 1.31 GPa for spherical tip. Results of nanoindentation tests show that this method is very useful and is perfect for obtaining mechanical properties of trabecular bone. Estimated values of elastic modulus are similar. The differences between hardness are significant but it is a result of using two different types of tips. However, it has to be emphasised that the differences in the values of elastic modulus and hardness result from different testing protocols, anisotropy and asymmetry of the micro-samples and the hydration of bone.

Keywords: human bone, mechanical properties, nano hardness nanoindentation, trabecular bone

Procedia PDF Downloads 276

Authors: Mohammad W. Dewan, Jahangir Alam, Khurshida Sharmin

Abstract:

Synthetic fibers (carbon, glass, aramid, etc.) are generally utilized to make composite materials for better mechanical and thermal properties. However, they are expensive and non-biodegradable. In the perspective of Bangladesh, jute fibers are available, inexpensive, and comprising good mechanical properties. The improved properties (i.e., low cost, low density, eco-friendly) of natural fibers have made them a promising reinforcement in hybrid composites without sacrificing mechanical properties. In this study, jute and e-glass fiber reinforced hybrid composite materials are fabricated utilizing hand lay-up followed by a compression molding technique. Room temperature cured two-part epoxy resin is used as a matrix. Approximate 6-7 mm thick composite panels are fabricated utilizing 17 layers of woven glass and jute fibers with different fiber layering sequences- only jute, only glass, glass, and jute alternatively (g/j/g/j---) and 4 glass - 9 jute – 4 glass (4g-9j-4g). The fabricated composite panels are analyzed through fiber volume calculation, tensile test, bending test, and water absorption test. The hybridization of jute and glass fiber results in better tensile, bending, and water absorption properties than only jute fiber-reinforced composites, but inferior properties as compared to only glass fiber reinforced composites. Among different fiber layering sequences, 4g-9j-4g fibers layering sequence resulted in better tensile, bending, and water absorption properties. The effect of chemical treatment on the woven jute fiber and chopped glass microfiber infusion are also investigated in this study. Chemically treated jute fiber and 2 wt. % chopped glass microfiber infused hybrid composite shows about 12% improvements in flexural strength as compared to untreated and no micro-fiber infused hybrid composite panel. However, fiber chemical treatment and micro-filler do not have a significant effect on tensile strength.

Keywords: compression molding, chemical treatment, hybrid composites, mechanical properties

Procedia PDF Downloads 158

Authors: Benaouda Hemza

Abstract:

This work on the characterization of structural elements in metal fiber concrete is devoted to the study of recyclability, as reinforcement for concrete, of chips resulting from the machining of steel parts. We are interested in this study to the rheological behavior of fresh chips reinforced concrete and its mechanical behavior at a young age. The evaluation of the workability with the LCL workabilimeter shows that optimal sand gravel ratios (S/G) are S/G=0.8, and S/G=1. The study of the content chips (W%) influence on the workability of the concrete shows that the flow time and the S/G optimum increase with W%. For S/G=1.4, the flow time is practically insensitive to the variation of W%, the concrete behavior is similar to that of self-compacting concrete. Mechanical characterization tests (direct tension, compression, bending, and splitting) show that the mechanical properties of chips concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: EUROSTEEL fibers corrugated and DRAMIX fibers). Chips provide a significant increase in strength and some ductility in the post-failure behavior of the concrete. Recycling chips as reinforcement for concrete can be favorably considered.

Keywords: fiber concrete, chips, workability, direct tensile test, compression test, bending test, splitting test

Procedia PDF Downloads 455

Authors: Ammari Abdelhammid

Abstract:

This work on the characterization of structural elements in metal fiber concrete is devoted to the study of recyclability, as reinforcement for concrete, of chips resulting from the machining of steel parts. We're interested in this study to the Rheological behavior of fresh chips reinforced concrete and its mechanical behavior at a young age. The evaluation of the workability with the LCL workabilimeter shows that optimal sand gravel ratios ( S/G) are S/G = 0.8 and S/G = 1. The study of the content chips (W%) influence on the workability of the concrete shows that the flow time and the S/G optimum increase with W%. For S/G = 1.4, the flow time is practically insensitive to the variation of W%, the concrete behavior is similar to that of self-compacting concrete. Mechanical characterization tests (direct tension, compression, bending, and splitting) show that the mechanical properties of chips concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: Eurosteel fibers corrugated and Dramix fibers). Chips provide a significant increase in strength and some ductility in the post-failure behavior of the concrete. Recycling chips as reinforcement for concrete can be favorably considered.

Keywords: fiber concrete, chips, workability, direct tensile test, compression test, bending test, splitting test

Procedia PDF Downloads 442

Authors: Arun C. O., Shrijith M. B., Thakur Rajesh Singh

Abstract:

The study aims to analyze and understand the biomechanical stability of the atlantoaxial complex under different posterior fixation techniques using the finite element method in the Indian context. The conventional cadaveric studies performed show heterogeneity in biomechanical properties. The finite element method being a versatile numerical tool, is being wisely used for biomechanics analysis of atlantoaxial complex. However, the biomechanics of posterior fixation techniques for an Indian subject is missing in the literature. It is essential to study in this context as the bone density and geometry of vertebrae vary from region to region, thereby requiring different screw lengths and it can affect the range of motion(ROM), stresses generated. The current study uses CT images for developing a 3D finite element model with C1-C2 geometry without ligaments. Instrumentation is added to this geometry to develop four models for four fixation techniques, namely C1-C2 TA, C1LM-C2PS, C1LM-C2Pars, C1LM-C2TL. To simulate Flexion, extension, lateral bending, axial rotation, 1.5 Nm is applied to C1 while the bottom nodes of C2 are fixed. Then Range of Motion (ROM) is compared with the unstable model(without ligaments). All the fixation techniques showed more than 97 percent reduction in the Range of Motion. The von-mises stresses developed in the screw constructs are obtained. From the studies, it is observed that Transarticular technique is most stable in Lateral Bending, C1LM-C2 Translaminar is found most stable in Flexion/extension. The Von-Mises stresses developed minimum in Trasarticular technique in lateral bending and axial rotation, whereas stress developed in C2 pars construct minimum in Flexion/ Extension. On average, the TA technique is stable in all motions and also stresses in constructs are less in TA. Tarnsarticular technique is found to be the best fixation technique for Indian subjects among the 4 methods.

Keywords: biomechanics, cervical spine, finite element model, posterior fixation

Procedia PDF Downloads 143

Authors: Vera Wilden, Benno Hoffmeister, Markus Feldmann

Abstract:

Glued laminated timber (glulam) is a preferred choice for long span girders, e.g., for gyms or storage halls. While the material provides sufficient strength to resist the bending moments, large spans lead to increased slenderness of such members and to a higher susceptibility to stability issues, in particular to lateral torsional buckling (LTB). Rules for the determination of the ultimate LTB resistance are provided by Eurocode 5. The verifications of the resistance may be performed using the so called equivalent member method or by means of theory 2nd order calculations (direct method), considering equivalent imperfections. Both methods have significant limitations concerning their applicability; the equivalent member method is limited to rather simple cases; the direct method is missing detailed provisions regarding imperfections and requirements for numerical modeling. In this paper, the results of a test series on slender glulam beams in three- and four-point bending are presented. The tests were performed in an innovative, newly developed testing rig, allowing for a very precise definition of loading and boundary conditions. The load was introduced by a hydraulic jack, which follows the lateral deformation of the beam by means of a servo-controller, coupled with the tested member and keeping the load direction vertically. The deformation-controlled tests allowed for the identification of the ultimate limit state (governed by elastic stability) and the corresponding deformations. Prior to the tests, the structural and geometrical imperfections were determined and used later in the numerical models. After the stability tests, the nearly undamaged members were tested again in pure bending until reaching the ultimate moment resistance of the cross-section. These results, accompanied by numerical studies, were compared to resistance values obtained using both methods according to Eurocode 5.

Keywords: experimental tests, glued laminated timber, lateral torsional buckling, numerical simulation

Procedia PDF Downloads 237

Authors: Nosakhare Enoma, Alphose Zingoni

Abstract:

The requirements for various toroidal shell forms are increasing due to new applications, available storage space and the consideration of appearance. Because of the complexity of some of these structural forms, the finite element method is nowadays mainly used for their analysis, even for simple static studies. This paper presents an easy-to-use analytical algorithm for pressurized multi-segmented toroidal shells of revolution. The membrane solution, which acts as a particular solution of the bending-theory equations, is developed based on membrane theory of shells, and a general approach is formulated for quantifying discontinuity effects at the shell junctions using the well-known Geckeler’s approximation. On superimposing these effects, and applying the ensuing solution to the problem of the pressurized toroid with four segments, closed-form stress results are obtained for the entire toroid. A numerical example is carried out using the developed method. The analytical results obtained show excellent agreement with those from the finite element method, indicating that the proposed method can be also used for complementing and verifying FEM results, and providing insights on other related problems.

Keywords: bending theory of shells, membrane hypothesis, pressurized toroid, segmented toroidal vessel, shell analysis

Procedia PDF Downloads 320

Authors: Ashish Kumar, Sanjeev Kumar Suman

Abstract:

This study investigated the influence of Cloisite-15A nanoclay on the physical, performance, and mechanical properties of bitumen binder. Cloisite-15A was blended in the bitumen in variegated percentages from 1% to 9% with increment of 2%. The blended bitumen was characterized using penetration, softening point, and dynamic viscosity using rotational viscometer, and compared with unmodified bitumen equally penetration grade 60/70. The rheological parameters were investigated using Dynamic Shear Rheometer (DSR), and mechanical properties were investigated by using Marshall Stability test. The results indicated an increase in softening point, dynamic viscosity and decrease in binder penetration. Rheological properties of bitumen increase complex modulus, decrease phase angle and improve rutting resistances as well. There was significant improvement in Marshall Stability, rather marginal improvement in flow value. The best improvement in the modified binder was obtained with 5% Cloisite-15A nanoclay.

Keywords: Cloisite-15A, complex shear modulus, phase angle, rutting resistance

Procedia PDF Downloads 394

Authors: S. S. Panda, Arkesh Chouhan, Yogesh Deshpande

Abstract:

The present paper deals with designing and fabricating an apparatus for the speedy and accurate manufacturing of fiber reinforced composite lamina of different orientation, thickness and stacking sequences for testing. Properties derived through an analytical approach are verified through measuring the elastic modulus, ultimate tensile strength, flexural modulus and flexural strength of the samples. The 0⁰ orientation ply looks stiffer compared to the 90⁰ ply. Similarly, the flexural strength of 0⁰ ply is higher than to the 90⁰ ply. Sample machinability has been studied by conducting numbers of drilling based on Taguchi Design experiments. Multi Responses (Delamination and Damage grading) is obtained using the desirability approach and optimum cutting condition (spindle speed, feed and drill diameter), at which responses are minimized is obtained thereafter. Delamination increases nonlinearly with the increase in spindle speed. Similarly, the influence of the drill diameter on delamination is higher than the spindle speed and feed rate.

Keywords: delamination, FRP composite, Taguchi design, multi response optimization

Procedia PDF Downloads 272

Authors: Sifeddine Abderrahmani, Sonia Bouafia

Abstract:

The finite element method is the most practical tool for the analysis of structures, whatever the geometrical shape and behavior. It is extensively used in many high-tech industries, such as civil or military engineering, for the modeling of bridges, motor bodies, fuselages, and airplane wings. Additionally, experience demonstrates that engineers like modeling their structures using the most basic finite elements. Numerous models of finite elements may be utilized in the numerical analysis depending on the interpolation field that is selected, and it is generally known that convergence to the proper value will occur considerably more quickly with a good displacement pattern than with a poor pattern, saving computation time. The method for creating finite elements using the strain approach (S.B.A.) is presented in this presentation. When the results are compared with those provided by equivalent displacement-based elements, having the same total number of degrees of freedom, an excellent convergence can be obtained through some application and validation tests using recently developed membrane elements, plate bending elements, and flat shell elements. The effectiveness and performance of the strain-based finite elements in modeling structures are proven by the findings for deflections and stresses.

Keywords: finite elements, plate bending, strain approach, displacement formulation, shell element

Procedia PDF Downloads 99

Authors: Yuxin Wu, Yu-Shing Wang, Zitao Zhang

Abstract:

A high-speed and time-lapse S-wave velocity measurement system has been built up for S-wave tomography in sand. This system is based on bender elements and applied to model pile tests in a tailor-made pressurized chamber to monitor the shear wave velocity distribution during pile installation in sand. Tactile pressure sensors are used parallel together with bender elements to monitor the stress changes during the tests. Strain gages are used to monitor the shaft resistance and toe resistance of pile. Since the shear wave velocity (Vs) is determined by the shear modulus of sand and the shaft resistance of pile is also influenced by the shear modulus of sand around the pile, the purposes of this study are to time-lapse monitor the S-wave velocity distribution change at a certain horizontal section during pile installation and to correlate the S-wave velocity distribution and shaft resistance of pile in sand.

Keywords: bender element, pile, shaft resistance, shear wave velocity, tomography

Procedia PDF Downloads 429

Authors: J. I. Aguwa, S. Sadiku, M. Abdullahi

Abstract:

This study examined the structural reliability of the Nigerian grown Opepe timber as bridge beam material. The strength of a particular specie of timber depends so much on some factors such as soil and environment in which it is grown. The steps involved are collection of the Opepe timber samples, seasoning/preparation of the test specimens, determination of the strength properties/statistical analysis, development of a computer programme in FORTRAN language and finally structural reliability analysis using FORM 5 software. The result revealed that the Nigerian grown Opepe is a reliable and durable structural bridge beam material for span of 5000mm, depth of 400mm, breadth of 250mm and end bearing length of 150mm. The probabilities of failure in bending parallel to the grain, compression perpendicular to the grain, shear parallel to the grain and deflection are 1.61 x 10^-7, 1.43 x 10^-8, 1.93 x 10^-4 and 1.51 x 10^-15 respectively. The paper recommends establishment of Opepe plantation in various Local Government Areas in Nigeria for structural applications such as in bridges, railway sleepers, generation of income to the nation as well as creating employment for the numerous unemployed youths.

Keywords: bending and deflection, bridge beam, compression, Nigerian Opepe, shear, structural reliability

Procedia PDF Downloads 467

Authors: Paola Pannuzzo, Tak-Ming Chan

Abstract:

In seismic applications, hollow steel sections show, beyond undeniable esthetical appeal, promising structural advantages since, unlike open section counterparts, they are not susceptible to weak-axis and lateral-torsional buckling. In particular, hot-finished hollow steel sections have homogeneous material properties and favorable ductility but have been underutilized for cyclic bending. The main reason is that the parameters affecting their hysteretic behaviors are not yet well understood and, consequently, are not well exploited in existing codes of practice. Therefore, experimental investigations have been conducted on a wide range of hot-finished rectangular hollow section beams with the aim to providing basic knowledge for evaluating their seismic performance. The section geometry (width-to-thickness and depth-to-thickness ratios) and the type of loading (monotonic and cyclic) have been chosen as the key parameters to investigate the cyclic effect on the rotational capacity and to highlight the differences between monotonic and cyclic load conditions. The test results provide information on the parameters that affect the cyclic performance of hot-finished hollow steel beams and can be used to assess the design provisions stipulated in the current seismic codes of practice.

Keywords: bending, cyclic test, finite element modeling, hollow sections, hot-finished sections

Procedia PDF Downloads 155

Authors: G. Bharath, K. S. Reddy, Vivek Tandon, M. Amaranatha Reddy

Abstract:

This paper presents the details of a study conducted to evaluate the interaction between recycled binder and fresh binder in Recycled Asphalt Pavement (RAP) mixes. When RAP is mixed with virgin aggregates in the presence of fresh binder there will be partial blending in a hot mix asphalt mixture. A recent approach used by some researchers for studying the degree of blending of RAP binder with virgin binder has been adopted in this study. Dense Bituminous Macadam mix of Ministry of Road Transport of India with a nominal maximum aggregate size of 19 mm was studied. Two proportions of RAP-20% and 35% and two types of virgin binders – viscosity grade VG10 and VG30 were considered. Design binder contents were determined for all the four types of mixes (two RAP contents and two virgin binders) as per Marshall mix design procedure. The degree of blending of RAP and virgin binders was evaluated in terms of the complex modulus of the binder. Laboratory test results showed that with an increase in RAP content, the degree of blending decreases. Better blending was observed for softer grade binder (VG10).

Keywords: blending, complex modulus, recycled asphalt pavement, virgin binder

Procedia PDF Downloads 432

Authors: Jisoo Kim, Jin-Young Choi, MinSu Lee, Sunmook Lee

Abstract:

Effects of ceramic nanoparticles on the improvement of durability of bone fixation devices have been investigated by assessing the durability of nanocomposite materials consisting of bioabsorbable polymer and ceramic nanoparticles, which could be applied for bone fixation devices such as plates and screws. Various composite ratios were used for the synthesis of nanocomposite materials by blending polylactic acid (PLA) and polyglycolic acid (PGA) as bioabsorbable polymer, and hydroxyapatite (HA) and tri-calcium phosphate (TCP) as ceramic nanoparticles. It was found that the addition of ceramic nanoparticles significantly enhanced the mechanical properties of the bone fixation devices compared to those fabricated with pure biopolymers. Particularly, the layer-by-layer approach for the fabrication of nanocomposites also had an effect on the improvement of bending strength. Durability tests were performed by measuring the changes in the bending strength of nanocomposite samples under varied temperature conditions for the accelerated degradation tests. It was found that Weibull distribution was the most proper one for describing the life distribution of devices in the present study. The mean lifetime was predicted by adopting Arrhenius Eq. Model for Stress-Life relationship.

Keywords: bioabsorbable, bone fixation device, ceramic nanoparticles, durability assessment, nanocomposite

Procedia PDF Downloads 326

Authors: Konrad Pietrykowski, Michał Gęca, Michał Bialy

Abstract:

The paper presents the results of the crankshaft strength simulation. The crankshaft was taken from the opposed piston engine. Calculations were made using finite element method (FEM) in Abaqus software. This program allows to perform strength tests of individual machine parts as well as their assemblies. The crankshaft that was used in the calculations will be used in the two-stroke aviation research aircraft engine. The assumptions for the calculations were obtained from the AVL Boost software, from one-dimensional engine cycle model and from the multibody model using the method developed in the MSC Adams software. The research engine will be equipped with 3 combustion chambers and two crankshafts. In order to shorten the calculation time, only one crankcase analysis was performed. The cut of the shaft has been selected with the greatest forces resulting from the engine operation. Calculations were made for two cases. For maximum piston force when maximum bending load occurs and for the maximum torque. Cast iron material was adopted. For this material, Poisson's number, density, and Young's modulus were determined. The computational grid contained of 1,977,473 Tet elements. This type of elements was chosen because of the complex design of the crankshaft. Results are presented in the form of stress distributions maps and displacements on the surface and inside the geometry of the shaft. The results show the places of tension stresses, however, no stresses are exceeded at any place. The shaft can thus be applied to the engine in its present form. Acknowledgement: This work has been realized in the cooperation with The Construction Office of WSK 'PZL-KALISZ’ S.A. and is part of Grant Agreement No. POIR.01.02.00-00-0002/15 financed by the Polish National Centre for Research and Development.

Keywords: aircraft diesel engine, crankshaft, finite element method, two-stroke engine

Procedia PDF Downloads 181

Authors: Abriak Yassine, Zri Abdeljalil, Benzerzour Mahfoud., Hadj Sadok Rachid, Abriak Nor-Edine

Abstract:

In this study, firstly, the study of the capacity reuse of dredged sediments and treated sediments with lime or cement were used in an establishment layer and the base layer of the roadway. Also, the analysis of mineral changes caused by the addition of lime or cement on the way as described in the mechanical results of stabilised sediments. After determining the quantity of lime and cement required to stabilise the sediment, the compaction characteristics were studied using the modified Proctor method. Then the evolution of the three parameters, that is, ideal water content and maximum dry density had been determined. Mechanical exhibitions can be assessed across the resistance to compression, flexibility modulus and the resistance under traction. The resistance of the formulation treated with cement addition (ROLAC®645) increase with the quantity of ROLAC®645. Traction resistances and the elastic modulus were utilized to assess the potential of the formulation as road construction materials utilizing classification diagram. The results show the various formulations with ROLAC® 645may be employed in subgrades and foundation layers for roads.

Keywords: cement, dredged, sediment, foundation layer, resistance

Procedia PDF Downloads 99

Authors: Elahe Moradi, Hossein Ali Khonakdar

Abstract:

In the context of the growing interest in renewable polymers, this study presents an innovative approach to environmental conservation through the development of an eco-friendly structure. The research focused on enhancing the compatibility between two immiscible polymers, poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT), using polyhedral oligomeric silsesquioxanes (POSS) nanoparticles with an epoxy functional group (Epoxy-POSS). This was achieved through a solution casting method. The study found that the modulus in the glassy region for blends containing Epoxy-POSS was significantly higher than that of the PLA/PBAT blend without Epoxy-POSS. However, in the transition and rubbery regions, the modulus of the Epoxy-POSS-containing blends was only marginally greater. From a mechanical properties’ perspective, the study demonstrated that the incorporation of POSS-EPOXY at varying concentrations enhanced the tensile strength of the PLA/PBAT blend by 30%, thereby acting as a reinforcement. This finding underscores the potential of this approach in the development of renewable polymers.

Keywords: Polyhedral oligomeric silsesquioxane, mechanical behavior, PLA, PBAT, nanocomposite

Procedia PDF Downloads 62

Authors: Pierre van Tonder, Dinesh Muthoo, Kim twiname

Abstract:

Many existing and newly built structures are constructed on the design basis of the engineer and the workmanship of the construction company. However, when considering larger structures where more people are exposed to the building, its structural integrity is of great importance considering the safety of its occupants (Raghu, 2013). But how can the structural integrity of a building be monitored efficiently and effectively. This is where the fourth industrial revolution step in, and with minimal human interaction, data can be collected, analysed, and stored, which could also give an indication of any inconsistencies found in the data collected, this is where the Fibre Bragg Grating (FBG) monitoring system is introduced. This paper illustrates how data can be collected and converted to develop stress – strain behaviour and to produce bending moment diagrams for the utilisation and prediction of the structure’s integrity. Embedded fibre optic sensors were used in this study– fibre Bragg grating sensors in particular. The procedure entailed making use of the shift in wavelength demodulation technique and an inscription process of the phase mask technique. The fibre optic sensors considered in this report were photosensitive and embedded in the slab and beams for data collection and analysis. Two sets of fibre cables have been inserted, one purposely to collect temperature recordings and the other to collect strain and temperature. The data was collected over a time period and analysed used to produce bending moment diagrams to make predictions of the structure’s integrity. The data indicated the fibre Bragg grating sensing system proved to be useful and can be used for structural health monitoring in any environment. From the experimental data for the slab and beams, the moments were found to be64.33 kN.m, 64.35 kN.m and 45.20 kN.m (from the experimental bending moment diagram), and as per the idealistic (Ultimate Limit State), the data of 133 kN.m and 226.2 kN.m were obtained. The difference in values gave room for an early warning system, in other words, a reserve capacity of approximately 50% to failure.

Keywords: fibre bragg grating, structural health monitoring, fibre optic sensors, beams

Procedia PDF Downloads 139

Authors: Ali Dehghan Manshadi, David H. StJohn, Matthew S. Dargusch, M. Qian

Abstract:

Biocompatible, highly porous titanium scaffolds were manufactured by metal injection moulding of spherical titanium powder (powder size: -45 µm) with potassium chloride (powder size: -250 µm) as a space holder. Property evaluation of scaffolds confirmed a high level of compatibility between their mechanical properties and those of human cortical bone. The optimum sintering temperature was found to be 1250°C producing scaffolds with more than 90% interconnected pores in the size range of 200-250 µm, yield stress of 220 MPa and Young’s modulus of 7.80 GPa, all of which are suitable for bone tissue engineering. Increasing the sintering temperature to 1300°C increased the Young’s modulus to 22.0 GPa while reducing the temperature to 1150°C reduced the yield stress to 120 MPa due to incomplete sintering. The residual potassium chloride was determined vs. sintering temperature. A comparison was also made between the porous titanium scaffolds fabricated in this study and the additively manufactured titanium lattices of similar porosity reported in the literature.

Keywords: titanium, metal injection moulding, mechanical properties, scaffolds

Procedia PDF Downloads 208

Authors: Shahab Hasani Nasab, Aran Aeini, Navid Kermanshahi

Abstract:

In order to reduce road building costs and reduce environmental damage, recycled materials can be used instead of mineral materials in the production of asphalt mixtures. Today, in most parts of the world, cold recycled asphalt with bitumen emulsion, has acceptable results. However, Cold Recycled Asphalt have some deficiency such as stripping, thermal cracking, and rutting. This requires the addition of additives to reduce this deficiency of recycled pavement with emulsified asphalt. In this research, nano-alumina and emulsified asphalt were used to modify the properties of recycled asphalt mixtures according to the technical specifications and the operation of cold recycling. Marshall test methods, dynamic creep test, and resiliency modulus test has been used to obtain the nano-alumina’s effects on asphalt mixture properties. The results show that the addition of nano-alumina would reduce the Marshall stability in samples but increases the rutting resistance. The resiliency modulus increases significantly with this additive.

Keywords: cold asphalt, cold recycling, nano-alumina, dynamic creep, bitumen emulsion

Procedia PDF Downloads 164

Authors: Kiatnarong Supapanmanee, Ekkarin Phongphinittana, Pongsak Nimdum

Abstract:

Natural fibers are readily available raw materials that are widely used as composite materials. The most common problem facing many researchers with composites made from this fiber is the adhesion between the natural fiber contact surface and the matrix material. Part of the problem is due to the hydrophilic properties of natural fibers and the hydrophobic properties of the matrix material. Based on the aforementioned problems, this research selected bamboo fiber, which is a strong natural fiber in the research study. The first step was to study the effect of the mechanical properties of the pure bamboo strip by testing the tensile strength of different measurement lengths. The bamboo strip was modified surface with sodium hydroxide (NaOH) at 6wt% concentrations for different soaking periods. After surface modification, the physical and mechanical properties of the pure bamboo strip fibers were studied. The modified and unmodified bamboo strips were molded into a composite material using epoxy as a matrix to compare the mechanical properties and adhesion between the fiber surface and the material with tensile and bending tests. In addition, the results of these tests were compared with the finite element method (FEM). The results showed that the length of the bamboo strip affects the strength of the fibers, with shorter fibers causing higher tensile stress. Effects of surface modification of bamboo strip with NaOH, this chemical eliminates lignin and hemicellulose, resulting in the smaller dimension of the bamboo strip and increased density. From the pretreatment results above, it was found that the treated bamboo strip and composite material had better Ultimate tensile stress and Young's modulus. Moreover, that results in better adhesion between bamboo fiber and matrix material.

Keywords: bamboo fiber, bamboo strip, composite material, bamboo composite, pure bamboo, surface modification, mechanical properties of bamboo, bamboo finite element method

Procedia PDF Downloads 92

Authors: Maryam Hasanali, Syed Mohammad Mojtabaei, Iman Hajirasouliha, G. Charles Clifton, James B. P. Lim

Abstract:

Cold-formed steel (CFS) elements are increasingly being used as main load-bearing components in the modern construction industry, including low- to mid-rise buildings. In typical multi-storey buildings, CFS structural members act as beam-column elements since they are exposed to combined axial compression and bending actions, both in moment-resisting frames and stud wall systems. Current design specifications, including the American Iron and Steel Institute (AISI S100) and the Australian/New Zealand Standard (AS/NZS 4600), neglect the beneficial effects of warping-restrained boundary conditions in the design of beam-column elements. Furthermore, while a non-linear relationship governs the interaction of axial compression and bending, the combined effect of these actions is taken into account through a simplified linear expression combining pure axial and flexural strengths. This paper aims to evaluate the reliability of the well-known Direct Strength Method (DSM) as well as design proposals found in the literature to provide a better understanding of the efficiency of the code-prescribed linear interaction equation in the strength predictions of CFS beam columns and the effects of warping-restrained boundary conditions on their behavior. To this end, the experimentally validated finite element (FE) models of CFS elements under compression and bending were developed in ABAQUS software, which accounts for both non-linear material properties and geometric imperfections. The validated models were then used for a comprehensive parametric study containing 270 FE models, covering a wide range of key design parameters, such as length (i.e., 0.5, 1.5, and 3 m), thickness (i.e., 1, 2, and 4 mm) and cross-sectional dimensions under ten different load eccentricity levels. The results of this parametric study demonstrated that using the DSM led to the most conservative strength predictions for beam-column members by up to 55%, depending on the element’s length and thickness. This can be sourced by the errors associated with (i) the absence of warping-restrained boundary condition effects, (ii) equations for the calculations of buckling loads, and (iii) the linear interaction equation. While the influence of warping restraint is generally less than 6%, the code suggested interaction equation led to an average error of 4% to 22%, based on the element lengths. This paper highlights the need to provide more reliable design solutions for CFS beam-column elements for practical design purposes.

Keywords: beam-columns, cold-formed steel, finite element model, interaction equation, warping-restrained boundary conditions

Procedia PDF Downloads 104

Authors: R. B. Adegbola, K. F. Oyedele, L. Adeoti

Abstract:

We present a method that utilizes Multi-channel Analysis of Surface Waves, which was used to measure shear wave velocities with a view to establishing the probable causes of road failure, subsidence and weakening of structures in some Local Government Area, Lagos, Nigeria. Multi channel Analysis of Surface waves (MASW) data were acquired using 24-channel seismograph. The acquired data were processed and transformed into two-dimensional (2-D) structure reflective of depth and surface wave velocity distribution within a depth of 0–15m beneath the surface using SURFSEIS software. The shear wave velocity data were compared with other geophysical/borehole data that were acquired along the same profile. The comparison and correlation illustrates the accuracy and consistency of MASW derived-shear wave velocity profiles. Rigidity modulus and N-value were also generated. The study showed that the low velocity/very low velocity are reflective of organic clay/peat materials and thus likely responsible for the failed, subsidence/weakening of structures within the study areas.

Keywords: seismograph, road failure, rigidity modulus, N-value, subsidence

Procedia PDF Downloads 363

Authors: Carla Ferreira, Helena Barros

Abstract:

The paper termed “Design of reinforced concrete with Eurocode 2” presents the theory regarding the design of reinforced concrete sections and the development of the tables and abacuses to verify the concrete section to the ultimate limit and service limit states. This paper is a complement of it, showing how to use the previous tools. Different numerical results are shown, proving the capability of the methodology. When a section of a beam is already chosen, the computer program presents the reinforcing steel in many locations along the structure, and it is the engineer´s task to choose the layout available for the construction, considering the maximum regular kind of reinforcing bars. There are many computer programs available for this task, but the interest of the present kind of tools is the fast and easy way of making the design and choose the optimal solution. Another application of these design tools is in the definition of the section dimensions, in a way that when stresses are evaluated, the final design is acceptable. In the design offices, these are considered by the engineers a very quick and useful way of designing reinforced concrete sections, employing variable strength concrete and higher steel classes. Examples of nonlinear analyses and redistribution of the bending moment will be considered, according to the Eurocode 2 recommendations, for sections under bending moment and axial forces. Examples of the evaluation of the service limit state will be presented.

Keywords: design examples, eurocode 2, reinforced concrete, section design

Procedia PDF Downloads 72

Authors: Ali Oveysi Sarabi

Abstract:

The dimensions of nanostructures are in the range of inter-atomic spacing of the structures which makes them impossible to be modeled as a continuum. Nanoscale size-effects on vibration analysis of nanobeams embedded in an elastic medium is investigated using different types of beam theory. To this end, Eringen’s nonlocal elasticity is incorporated to various beam theories namely as Euler-Bernoulli beam theory (EBT), Timoshenko beam theory (TBT), Reddy beam theory (RBT), and Levinson beam theory (LBT). The surrounding elastic medium is simulated with both Winkler and Pasternak foundation models and the difference between them is studies. Explicit formulas are presented to obtain the natural frequencies of nanobeam corresponding to each nonlocal beam theory. Selected numerical results are given for different values of the non-local parameter, Winkler modulus parameter, Pasternak modulus parameter and aspect ratio of the beam that imply the effects of them, separately. It is observed that the values of natural frequency are strongly dependent on the stiffness of elastic medium and the value of the non-local parameter and these dependencies varies with the value of aspect ratio and mode number.

Keywords: nanobeams, free vibration, nonlocal elasticity, winkler foundation model, Pasternak foundation model, beam theories

Procedia PDF Downloads 536

Authors: Benalia Kouini, Aicha Serier

Abstract:

This work aims to investigate the structure–property relationship in ternary nanocomposites consisting of polypropylene as the matrix, polyamide 66 as the minor phase and treated nanoclay DELLITE 67G as the reinforcement. All PP/PA66/Nanoclay systems with polypropylene grafted maleic anhydride PP-g-MAH as a compatibilizer were prepared via melt compounding and characterized in terms of nanoclay content. Morphological structure was investigated by scanning electron microscopy. The rheological behavior of the nanocomposites was determined by various methods, viz melt flow index (MFI) and parallel plate rheological measurements. The PP/PP-g-MAH/PA66 nanocomposites showed a homogeneous morphology supporting the compatibility improvement between PP, PA66 and nanoclay. SEM results revealed the formation of nanocomposites as the nanoclay was intercalated and exfoliated. In the ternary nanocomposites, the rheological behavior showed that, the complex viscosity is increased with increasing the nanoclay content; however, at low frequencies this increase is governed by the content of nanofiller while at high frequencies it is mainly determined by talc content. A similar trend was also observed for the variations of storage modulus (G′) and loss modulus (G″) with frequency. The results showed that the use of nanoclay considerably affects the melt elasticity.

Keywords: nanocomposites, polypropylene, polyamide66, modified nanoclay, rheology

Procedia PDF Downloads 385

Authors: Krunal Thakar

Abstract:

Wire ropes combine high tensile strength and flexibility as compared to other general steel products. They are used in various application areas such as cranes, mining, elevators, bridges, cable cars, etc. The earliest reported use of wire ropes was for mining hoist application in 1830s. Over the period, there have been substantial advancement in the design of wire ropes for various application areas. Under operational conditions, wire ropes are subjected to varying tensile loads and bending loads resulting in material wear and eventual structural failure due to fretting fatigue. The conventional inspection methods to determine wire failure is only limited to outer wires of rope. However, till date, there is no effective mathematical model to examine the inter wire contact forces and wear characteristics. The scope of this paper is to present a computational simulation technique to evaluate inter wire contact forces and wear, which are in many cases responsible for rope failure. Two different type of ropes, IWRC-6xFi(29) and U3xSeS(48) were taken for structural strength evaluation and wear prediction. Both ropes have a double helix twisted wire profile as per JIS standards and are mainly used in cranes. CAD models of both ropes were developed in general purpose design software using in house developed formulation to generate double helix profile. Numerical simulation was done under two different load cases (a) Axial Tension and (b) Bending over Sheave. Different parameters such as stresses, contact forces, wear depth, load-elongation, etc., were investigated and compared between both ropes. Numerical simulation method facilitates the detailed investigation of inter wire contact and wear characteristics. In addition, various selection parameters like sheave diameter, rope diameter, helix angle, swaging, maximum load carrying capacity, etc., can be quickly analyzed.

Keywords: steel wire ropes, numerical simulation, material wear, structural strength, axial tension, bending over sheave

Procedia PDF Downloads 152

Authors: G. A. Rombach, A. Faron

Abstract:

Crack formation and growth in reinforced concrete members are, in many cases, the cause of the collapse of technical structures. Such serious failures impair structural behavior and can also damage property and persons. An intensive investigation of the crack propagation is indispensable. Numerical methods are being developed to analyze crack growth in an element and to detect fracture failure at an early stage. For reinforced concrete components, however, further research and action are required in the analysis of shear cracks. This paper presents numerical simulations and continuum mechanical modeling of bending shear crack propagation in a three-dimensional reinforced concrete beam without transverse reinforcement. The analysis will provide a further understanding of crack growth and redistribution of inner forces in concrete members. As a numerical method to map discrete cracks, the extended finite element method (XFEM) is applied. The crack propagation is compared with the smeared crack approach using concrete damage plasticity. For validation, the crack patterns of real experiments are compared with the results of the different finite element models. The evaluation is based on single span beams under bending. With the analysis, it is possible to predict the fracture behavior of concrete members.

Keywords: concrete damage plasticity, crack propagation, extended finite element method, fracture mechanics

Procedia PDF Downloads 119

Authors: Y. Seki, A. Ç. Kılıç, M. Atagür, O. Özdemir, İ. Şen, K. Sever, Ö. Seydibeyoğlu, M. Sarikanat, N. Küçükdoğan

Abstract:

Cheap and abundant waste materials have been investigated as filler materials in thermoplastic polymers instead of wood- based materials because of deforestation. Vine stem, as an agricultural waste, was used as a filler material for a thermoplastic polymer, high-density polyethylene (HDPE) in this study. Agricultural waste of vine stem was collected from Manisa region, Turkey. Vine stem at different rations was used to reinforce HDPE. The effect of vine stem loading on tensile strength and Young’s modulus of composites were obtained. It was clearly observed that tensile strength and Young’s modulus of HDPE was increased by vine stem loading. Thermal stabilities of composites were obtained by using thermogravimetric analysis. Water absorption behavior of HDPE was improved by loading vine stem into HDPE. The crystallinity index values of neat HDPE and vine stem loaded HDPE composites were investigated byX-ray diffraction analysis. From this study, it was inferred that vine stem, as an agricultural waste, can be used as a filler material for HDPE.

Keywords: waste filler, high density polyethylene, composite, composite materials

Procedia PDF Downloads 517