Simulation Of Mechanical Behavior Research Articles

Numerical Simulation for Mechanical Behavior of Carbon Black Filled Rubber Composites Based on Cubic Representative Volume Element

Based on the connection between macroscopic and microscopic characteristics of carbon black filled rubber composites, Representative Volume Element (RVE) containing one single particle has been proposed, and three dimensional cubic RVE has been established to study and analyze the macroscopic mechanical properties of the carbon black filled rubber composites by the micromechanical finite element method. The research shows that the stiffness of the composite is increased with the increase of the volume fraction of carbon black filler particles. By comparison, it is shown that the results of the predictions on the stress-strain behavior of the rubber composite made with the cubic RVE numerical models containing one spherical particle are in good agreement with the experimental results for seven and fifteen percent carbon black filler content, but there is some discrepancy between them for twenty-five percent carbon black filler content. The results of the predictions on the stress-strain behavior of the rubber composite made with the cubic RVE numerical models containing one cubical particle are higher than the experimental results, and the higher the carbon black filler content, the greater is the discrepancy between them.

Finite Element Analysis on the Fire Resistance of the Effect of Thickness of Elliptical Steel Tubular Columns Filled with Concrete at Elevated Temperature

elliptical Concrete-filled steel tubular (ECFT) columns are often used as the main supporting columns for high-rise buildings and has become a topic of academic concern. The past research about ECFT most focused on its ultimate strength and mechanical behavior. The experiment method which is usually expensive and time-consuming. Other research methods include combining experimental data with appropriate theory to design or calculate the structural properties, and these methods tend to have a conservative assessment of the results. Therefore, some researches have been developing finite element model to simulate and analyze the ultimate strength and buckling condition of ECFT and its component behavior. In this paper, finite element analysis is used to explore the mechanical behavior of ECFT during exerting axial compression load. Contact pair settings and friction coefficient settings were compared with different pattern to investigate the accuracy of simulation and the mechanical behavior of ECFT columns. Study found that the ultimate strength for ECFT columns obtained by finite element analysis can achieve good accuracy, and in the meantime the mechanical behavior simulation of ECFT columns with proper finite element settings could be achieved.

Digital Image Technology – Based Simulation for Internal Components and Mechanical Behavior of Asphalt Concrete

Digital image technology – based computer aided design for asphalt concrete is a new direction of asphalt pavement research. This paper focuses on description of research progress achieved by the author’s research institute in the direction, mainly including two-dimensional digital image technology – based research in the internal structure and volume of asphalt concrete, industrial CT-based identification of different substances in the asphalt concrete and acquisition of morphological characteristics for coarse aggregate and three-dimensional digital image technology – based virtual reconstruction of asphalt concrete and simple mechanical behavior simulation.

3D simulation of dependence of mechanical properties of porous ceramics on porosity

3D computer simulation of mechanical behavior of a brittle porous material under uniaxial compression is considered. The movable cellular automaton method, which is a representative of particle methods in solid mechanics, is used for computation. In an initial structure the automata are positioned in fcc packing. The pores are set up explicitly by removing single automata from the initial structure. The computational results show that dependence of strength and elastic properties of the modeled material on porosity below percolation threshold (material with closed pores) differs from the dependence for porosity above the threshold (permeable material). The results obtained are in close agreement with available experimental data.

Molecular dynamics simulation of mechanical behavior of osteopontin-hydroxyapatite interfaces

Bone is characterized with an optimized combination of high stiffness and toughness. The understanding of bone nanomechanics is critical to the development of new artificial biological materials with unique properties. In this work, the mechanical characteristics of the interfaces between osteopontin (OPN, a noncollagenous protein in extrafibrillar protein matrix) and hydroxyapatite (HA, a mineral nanoplatelet in mineralized collagen fibrils) were investigated using molecular dynamics method. We found that the interfacial mechanical behavior is governed by the electrostatic attraction between acidic amino acid residues in OPN and calcium in HA. Higher energy dissipation is associated with the OPN peptides with a higher number of acidic amino acid residues. When loading in the interface direction, new bonds between some acidic residues and HA surface are formed, resulting in a stick–slip type motion of OPN peptide on the HA surface and high interfacial energy dissipation. The formation of new bonds during loading is considered to be a key mechanism responsible for high fracture resistance observed in bone and other biological materials.

The exoskeletal structure and tensile loading behavior of an ant neck joint

Insects have evolved mechanical form and function over millions of years. Ants, in particular, can lift and carry heavy loads relative to their body mass. Loads are lifted with the mouthparts, transferred through the neck joint to the thorax, and distributed over six legs and tarsi (feet) that anchor to the supporting surface. While previous research has explored attachment mechanisms of the tarsi, little is known about the relation between the mechanical function and the structural design and material properties of the ant. This study focuses on the neck – the single joint that withstands the full load capacity. We combine mechanical testing, computed tomography (CT), scanning electron microscopy (SEM), and computational modeling to better understand the mechanical structure–function relation of the neck joint of the ant species Formica exsectoides (Allegheny mound ant). Our mechanical testing results show that the soft tissue forming the neck joint of F. exsectoides exhibits an elastic modulus of 230±140MPa and can withstand ~5000 times the ant's weight. We developed a 3-dimensional (3D) model of the structural components of the neck joint for simulation of mechanical behavior. Finite element (FE) simulations reveal the neck-to-head transition where the soft membrane material meets the hard exoskeleton as the critical point for failure of the neck joint, which is consistent with our experiments. Our results further indicate that the neck joint structure exhibits anisotropic mechanical behavior with the highest stiffness occurring when the load path is aligned with the axis of the neck.

A mixed elastohydrodynamic lubrication model with layered elastic theory for simulation of chemical mechanical polishing

Mixed elastohydrodynamic lubrication (mixed EHL) model has been successfully used to study phenomena in chemical mechanical polishing (CMP) process. However, in various mixed EHL simulation frameworks, a polishing pad's deformation cannot correctly be described by adopted models for pad deformation such as elastic half-space model and Winkler elastic foundation model. Thus, a more accurate model for pad deformation is needed, since this is the prerequisite for an accurate prediction of contact pressure and material removal rate, which is critical for improvement of polishing quality. In this paper, a layered elastic theory, which is frequently used to calculate flexible pavement response to truck loading, is introduced into the mixed EHL model. It is found that this theory has a similar accuracy to the traditional 3D finite element method for calculating the pad deformation. However, its computational cost is much lower, which is especially important for accurate and efficient simulation of mechanical behavior and material removal rate (MRR) in CMP. In order to highlight benefits of the proposed theory, simulations are carried out based on three different pad deformation models with the mixed EHL model. The pad deformation behavior is found to have a significant influence on the final simulation results, especially the MRR prediction. By comparing the different simulation models, the proposed layer elastic theory is found to be an optimal model for describing the polishing pad deformation behavior in CMP and can provide accurate simulation results on contact pressure distribution and the material removal rate.

Simulation of mechanical behaviour of cast aluminium components

A literature review on methods to consider the mechanical behaviour of cast aluminium alloys in finite element method (FEM) simulations of cast aluminium components has been performed. The mechanical behaviour is related to several microstructural parameters achieved during the casting process. Three different methods to consider these microstructural parameters are introduced. One method predicts the mechanical behaviour of the component using casting process simulation software. The other two methods implement numerical models for the mechanical behaviour of cast aluminium into the FEM simulation. Applications of the methods are shown, including combinations with statistical methods and geometry optimisation methods. The methods are compared, and their different strengths and drawbacks are discussed.

CAD model simplification using a removing details and merging faces technique for a FEM simulation

The simulation process is currently used in the design and dimensioning of mechanical parts. With the progress of computer materials, the finite elements method (FEM) becomes the most used approach in the simulation of mechanical behaviour. The simulation process needs multiple Design-FEM loops. In order to accelerate those analysis loops, an adaptation of computer aided design (CAD) model is necessary. The adaptation step consists in the simplification of the CAD model geometry by eliminating details (holes, chamfers, fillet, etc.) and faces. In this paper, a novel technique of simplification of the CAD geometry is developed. This technique is a hybrid method based on a combination of the elimination details and merging faces. The merging of faces is based on the energetic method. With this approach, the computing time is reduced by the elimination of geometric details which do not boundary conditions. An implementation of the proposed algorithm on the Open Cascade platform is also presented. The results of the developed method are compared with a previous publication. The reduction of the computing time and the amelioration of the result precision highlight the efficiency of the presented method.

Development of a full range multi-scale model to obtain elastic properties of CNT/polymer composites

The main goal of this study was to develop a full range multi-scale modeling technique to extract Young’s modulus and Poisson’s ratio of carbon nanotube reinforced polymer (CNTRP) composites covering all nano, micro, meso and macro scales. The developed model consists of two different phases as top-down scanning and bottom-up modeling. At the first stage, the material region will be scanned from the macro level downward to the nano-scale. Effective parameters associated with each scale will be identified through this scanning procedure. Taking into account identified effective parameters of each specific scale, the suitable representative volume elements (RVE) will be defined for all nano, micro, meso and macro scales, separately. In the second stage of the modeling procedure, a hierarchical multi-scale modeling approach is developed. This modeling strategy would analyze the material at each scale and obtained results that were fed to the upper scale as input information. Due to involved random parameters, the developed modeling technique is implemented stochastically. It has been shown that the developed modeling procedure provides a clear insight to the properties of CNTRP and it is a very efficient tool for simulation of mechanical behavior of CNTRP composites. A sensitivity analysis was conducted to quantify the influence of the identified random parameters on the overall behavior of CNTRP.

Analysis of the Mechanical Behavior of Short Tube Columns Filled with Concrete by Different Contact Surface Conditions

Concrete-filled steel tubular(CFT) columns are often used as the main supporting columns for high-rise buildings and has become a topic of academic concern. The past research about CFT most focused on its ultimate strength and mechanical behavior. The experiment method which is usually expensive and time-consuming. Other research methods include combining experimental data with appropriate theory to design or calculate the structural properties, and these methods tend to have a conservative assessment of the results. Therefore, some researches have been developing finite element model to simulate and analyze the ultimate strength and buckling condition of CFT and its component behavior. In this paper, finite element analysis is used to explore the mechanical behavior of CFT during exerting axial compression load. Contact pair settings and friction coefficient settings were compared with different pattern to investigate the accuracy of simulation and the mechanical behavior of CFT columns. Study found that the ultimate strength for CFT columns obtained by finite element analysis can achieve good accuracy, and in the mean time the mechanical behavior simulation of CFT columns with proper finite element settings could be achieved.

Numerical Simulation for Mechanical Behavior of Carbon Black Filled Rubber Composites Based on Plane Stress Model

In this paper, Representative Volume Element with random distribution pattern has been built and applied to study and analyze the macro mechanical properties of the carbon black filled rubber composites by the micromechanical finite element method. And numerical simulations under uniaxial compression have been made by two-dimensional plane stress model. The periodic boundary conditions are imposed on each Representative Volume Element in order to ensure the compatibility of the deformation field. The dependence of the macroscopic stress-strain behavior and the effective elastic modulus of the composites, on particle distribution pattern, particle volume fraction and particle stiffness has been investigated and discussed. It is shown that the stiffness of the composite is increased considerably with the introduction of carbon black filler particles, and the effective elastic modulus of the composite is increased with the increase of the particle volume fraction.

Numerical simulation of mechanical behaviors of degradable porous bioceramics with cracks

Hydroxyapatite bioceramics is simulated by using finite element method (FEM). The influences of porosity, hole shape, angle of crack and other parameters on the ceramics are analyzed. The results show that with the increase of the angle between crack and horizontal direction, the stress intensity factor KI decreases gradually, but stress intensity factor KII increases at first and then it decreases. The value of KII reaches maximum when the angle between crack and horizontal direction is 45°. KI and KII rise with the increase of porosity, and they are almost the same for the circular and hexagonal holes. For elliptical holes, KI and KII reach maximum when the long axis of ellipse is perpendicular to the loading direction and they reach minimum when the same axis is parallel to the loading direction. Moreover, with the increase of the angle between the long axis and loading direction, KI and KII increase gradually.

Study on Mechanical Properties of Talus Deposit Based on Digital Image Processing Technology

Talus deposit is often seen in the hydropower projects in the southwest of China. Its mechanical properties are so complex that microstructure study is often used to reveal the essence of deformation and damage. The digital image processing technology (DIPT) is introduced to the simulation of talus deposits. Based on the study of DIPT, a Photo-To-Flac3D (PTF) auto-modeling program is developed. It is able to realize the whole process: analyzing and processing the digital image, acquiring the information and establishing the micro-model files. A new modeling method is developed for the mechanical behavior simulation of talus deposit. As an example, some talus deposit data of Gushui hydropower station is used, the micro-model of talus deposit can be established fast and correctly by the PTF from the digital photo on-site. The mechanical properties are studied by the numerical simulation of triaxial test. The results show that the talus deposit has the feature of bully in deformation while that of Unicom band under force.

Mechanical Properties Identification of Viscoelastic/Hyperplastic Materials Using Haptic Device Based Experimental Setup

Mechanical behavior simulation of viscoelastic materials is a difficult task. In order to obtain accurate simulations, material model should be well chosen and hyperelastic characteristics of the viscoelastic materials should also be incorporated in the model. Once the material model is selected the coefficients can be identified with the help of mechanical tests/experiments. The main goal of this study is to optimize material model’s coefficients by using the designed indenter test setup results and inverse finite element modeling. Indenter test setup was designed by using a haptic device, force sensor and data acquisition card to test the mechanical properties of the viscoelastic/hyperelastic materials. Inverse finite element modeling method is used in order to model the materials according to their material characteristics. The model obtained from the analysis was optimized by using the data obtained from indenter tests. The conformity of the chosen model and the tested materials is shown by inverse finite element modeling and the material model coefficients are proved to be identified correctly.

Numerical Simulation of Mechanical Behaviour of Cement Paste under Compressive Pressure

This paper contributes to numerically study the mechanical behavior of cement paste under compressive pressure. First, the main results from an experimental study on the mechanical behavior of cement paste are studied. Then an elastoplastique model with two flow mechanisms is proposed to describe the mechanical behavior of cement paste subjected to confining pressure. A particular emphasis is put on the pore collapse mechanism which is developed at higher confining pressure. Finally, numerical simulations and experimental data are compared in order to verify the capacity of the proposed model to reduce numerically the basic characteristics of cement paste under different levels of confining pressure.

Strategies for integration of 3-D experimental data with modeling and simulation

For the most comprehensive modeling and prediction of materials behavior at the microscale, experimentally measured three-dimensional (3-D) microstructural datasets must be incorporated as initial input into computational models. Although the capability to collect and store large amounts of 3-D microstructural data is advancing continuously, computational resources for the processing and simulation can limit the amount of data that can be analyzed. Depending on the features and properties of interest, several approaches can be applied to optimize processing, reduce the amount of data that needs to be simulated, and increase the efficiency of simulations to maximize the statistical significance of microstructure analyses. This paper presents examples of four such approaches to efficient integration of large 3-D datasets into modeling and simulations of mechanical behavior in an efficient yet statistically significant manner.

Characterization and Simulation of Mechanical Behavior of 6063 Aluminum Alloy Thin-Walled Tubes

The material characterization and mechanical behaviors of aluminum alloy (6063) were investigated using flat specimens and the butterfly specimens with a modified Arcan fixture. The butterfly specimens were tensile-loaded at various stress triaxiality by changing the loading angles of the Arcan fixture. The flat specimens were tensile-loaded at various strain rates. The results of tensile tests at various stress triaxiality showed that the curves of engineering stress-engineering strain are obviously different. The results of different strain rates tensile tests showed that the yield stress and fracture stress increased slightly with strain rates increasing, however the fracture strain decreased obviously with strain rates increasing, and the ultimate strength almost remained constant. The Johnson-cook constitutive model could be used to describe the dynamic axial crashing behavior of thin-walled 6063 aluminum alloy tubes under impact loading. The material constants of the Johnson-cook constitutive model and failure model were acquired to be used for FEM simulation through material characterization.

Numerical Simulation of Mechanical Behavior on Landslides Triggered by Heavy Rainfall

Deformation instability of slope due to rain was one of the most common geological disasters. Speaking from the mechanism, the destructive action and triggering action of rainfall affected the stability of slope itself, which made the slope deform and even lead to instability. June 28, 2010, Guanling in Guizhou province a large landslide occurred which triggered by continuous heavy rainfall, it caused that in two village-groups 107 villagers were buried, all the tragedy of houses were completely destroyed. Using finite element software ANSYS to simulate the mechanical behavior of the landslide, to analyze the deformation mechanism, we got that the large landslide deformation mechanism was a complex mechanical geological process. From the analysis of interaction between soil and rock, the landslide showed complex mechanical geological features. As rainfall increased the strength of unsaturated soil and weak intercalation reduced, this strengthened the role of the slope deformation and failure. The lock-fixed section first appeared brittle fracture, then that brought shear failure to the creeping section. The interaction between lock-fixed section and creeping section was the key of slope failure.

Simulation of mechanical behavior of temperature-responsive braided stents made of shape memory polyurethanes

Polymeric stents can be considered as an alternative to metallic stents thanks to their lessened incidence of restenosis and controlled deployment. The purpose of this study was to investigate the feasibility of developing a temperature-responsive braided stent using shape memory polyurethane (SMPU) through finite element analysis. It was assumed that braided stents were manufactured using SMPU fibers. The mechanical behavior of SMPU fibers was modeled using a constitutive equation describing their one-dimensional thermal-induced shape memory behavior. Then, the braided stents were analyzed to investigate their mechanical behavior using finite element analysis software, in which the constitutive equation was implemented through a user material subroutine. The diameter of the SMPU fibers and braiding angle were chosen as the design parameters and their values were adjusted to ensure that the mechanical properties of the braided polymer stents match those of metallic stents. Finally, the deployment process of the braided stents inside narrowed vessels was simulated, showing that the SMPU stents can be comfortably implanted while minimizing the overpressure onto the vessel walls, due to their thermo-responsive shape memory behavior.