Monolithic Roadbed's Mechanical Behavior Affected by Structural Thickness under Tram

2013 ◽  
Vol 361-363 ◽  
pp. 1664-1670
Author(s):  
Chong Wei Huang ◽  
Er Hao Su ◽  
Xian Zhi Shao ◽  
Yi Zhang ◽  
Lie Ping Wang
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Tensile Stress ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Contact Problems ◽  
Element Model ◽  
Nonlinear Contact ◽  
Structure Layer ◽  
Abaqus Software

Based on ABAQUS software, a 3-D finite element model which content the nonlinear contact problems and contact-earth subgrade-monilithic was given to analysis the mechanical behavior of the monolithic roadbed. Mechanics behavior and deflection of the monolithic roadbed, deflection and compressive stress of earth subgrade evaluated in detail with respect to varied structure layer combination and materials parameters. The results indicate that the increase roadbed thickness can significantly reduce the monolithic roadbeds tensile stress, which can reach 1.042MPa. With the increase of the friction coefficient, level of tensile stress σdy, monolithic deflection Dd , the compressive stress σsz and deflection on earth subgrade were slightly reduced.

scholarly journals Analysis of Influence and Formation for Uncoordinated Deformation in Tram Subgrade

2019 ◽  
Vol 136 ◽  
pp. 04037
Author(s):  
Yang Cai ◽  
Chongwei Huang ◽  
Xi Chen ◽  
Yu Sun ◽  
Dandan Guo
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Finite Element Model ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Mechanical Response ◽  
Element Model ◽  
The Other ◽  
3D Finite Element ◽  
Remarkable Effect

Aiming at horizontal and vertical uncoordinated deformation formation in Tram Subgrade, a 3D finite element model was established, which was used to analyse the mechanical response of tram monolithic roadbed on multiple depth and width of uncoordinated deformation. The results show that the uncoordinated deformation’s depth has little influence on the mechanical behavior of roadbed, and it indicates that there was remainder disengaging under the monolithic roadbed by the load of tram. On the other side, the width of uncoordinated deformation has a remarkable effect on outstanding to the horizontal tensile stress (σdy) in the slab bottom, deflection (Dd) on the top of slab, compressive stress (σsz) on the top of soil, and deflection (Dss) on the top of soil. The deflection on the top of subgrade surface is about 1.61mm. Therefore, the designer’s attention should be paid to avoid uncoordinated deformation width in the project, and avoid destroy of monolithic slab.

Stress Analysis of a Novel MEMS Microphone Chip Using Finite Element Analysis

2005 ◽  
Author(s):  
Jia Gao ◽  
Ronald N. Miles ◽  
Weili Cui
Keyword(s):  
Finite Element ◽  
Low Temperature ◽  
Tensile Stress ◽  
Finite Element Model ◽  
Oxide Layer ◽  
Compressive Stress ◽  
Failure Modes ◽  
Element Model ◽  
Mems Devices ◽  
Mems Microphone

Residual stress produces major challenges in the fabrication of MEMS devices. This is particularly true in the development of MEMS microphones since the response of the thin sound-sensitive diaphragm is strongly affected by stress. It is important to predict the effects of fabrication stress on the microphone chip and identify the failure modes to ensure a satisfactory fabrication yield. In this study, a finite element model of the microphone chip is developed to analyze the laminated structure under different fabrication stresses. The model of the microphone chip includes the diaphragm, backplate and sacrificial oxide layers on top of the silicon substrate. Fabrication stresses are included through the use of an equivalent thermal stress. The stresses in the different layers have been estimated based on measurements performed on fabricated test structures. The estimated stresses are simulated in the finite element model. An important factor in determining the process reliability is the compressive stress of the low temperature sacrificial oxide layer (LTO). A variety of stress combinations between different layers with the low temperature oxide layer are investigated. It is found that an adequate level of tensile stress in the backplate is crucial to ensure the fabrication yield. In the designs considered here, silicon nitride in combination with a thin conductive layer is identified as a favorable material for the backplate considering its high modulus and tensile stress in ‘as deposited’ film. In addition, the presence of a LTO layer on the backside of the wafer turns out to be very helpful in reducing the deflection of the unreleased chip and the stress in the diaphragm. In the case where there is a net compressive stress in the laminate, the failure mode is identified by nonlinear analysis. This analysis provides a guideline to select robust materials and tune the fabrication process to ensure a satisfactory fabrication yield.

Numerical analyses on mechanical performance of flat buried approach slab and soil deformation

2021 ◽  
Author(s):  
Junqing Xue ◽  
Dong Xu ◽  
Yufeng Tang ◽  
Bruno Briseghella ◽  
Fuyun Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Parametric Analysis ◽  
Mechanical Performance ◽  
Element Model ◽  
Soil Deformation ◽  
Longitudinal Deformation ◽  
Expansion Joints ◽  
Approach Slab ◽  
Jointless Bridges

<p><br clear="none"/></p><p>The vulnerability problem of expansion joints could be fundamentally resolved using the concept of jointless bridges. The longitudinal deformation of the superstructure can be transferred to the backfill by using the approach slab. The flat buried approach slab (FBAS) has been used in many jointless bridges in European countries. In order to understand the mechanical performance of FBAS and soil deformation, a finite element model (FEM) was implemented in PLAXIS. Considering the friction between the FBAS and soil, the buried depth, the FBAS length and thickness as parameters, a parametric analysis was carried out. According to the obtained results and in order to reduce the soil deformation above the FBAS, it is suggested to increase the friction between the FBAS and sandy soil, and the buried depth of FBAS. Moreover, it should be paid attention to the vertical soil deformation and the concrete tensile stress of FBAS in pulling condition.</p>

Maximum Stress at Intersecting Bores of Pressurized Blocks

1994 ◽  
Author(s):  
Ajay Garg
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Stress ◽  
Element Model ◽  
Maximum Tensile Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Empirical Methods ◽  
Element Analysis ◽  
Matched Design

Abstract In high pressure applications, rectangular blocks of steel are used instead of cylinders as pressure vessels. Bores are drilled in these blocks for fluid flow. Intersecting bores with axes normal to each other and of almost equal diameters, produce stresses which can be many times higher than the internal pressure. Experimental results for the magnitude of maximum tensile stress along the intersection contour were available. A parametric finite element model simulated the experimental set up, followed by correlation between finite element analysis and experimental results. Finally, empirical methods are applied to generate models for the maximum tensile stress σ11 at cross bores of open and close ended blocks. Results from finite element analysis and empirical methods are further matched. Design optimization of cross bores is discussed.

scholarly journals Experimental Study of Friction Resistance between Steel and Concrete in Prefabricated Composite Beam with High-Strength Frictional Bolt

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Qi Guo ◽  
Qing-wei Chen ◽  
Ying Xing ◽  
Ya-ning Xu ◽  
Yi Zhu
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Concrete Strength ◽  
High Strength ◽  
Element Model ◽  
Construction Time ◽  
Friction Behavior ◽  
Friction Resistance

Prefabrication of composites beam reduces the construction time and makes them easily to be assembled, deconstructed, and partially repaired. The use of high-strength frictional bolt shear connectors can greatly enhance the sustainability of infrastructure. However, researches about the concrete-steel friction behavior are very limited. To provide a contribution to this area, 21 tests were conducted to measure the friction coefficient and slip stiffness with different concrete strength, steel strength, and surface treatment of steel. An effective finite element model was developed to investigate the ultimate bearing capacity and load-slip characteristics of bolt shear connection. The accuracy of the proposed finite element model is validated by the tests in this paper. The results demonstrate a positive correlation between concrete strength and friction coefficient and better performance of shot-blasted steel. It is also proved that high-strength frictional bolt has a 30% lower bearing capacity but better strength reserve and antiuplifting than the headed stud.

Nonlinear contact problems—A finite element approach implemented in ADINA

1985 ◽  
Vol 21 (1-2) ◽  
pp. 69-80 ◽  
Author(s):  
Gerhard Mehlhorn ◽  
Johann Kollegger ◽  
Manfred Keuser ◽  
Wolfgang Kolmar
Keyword(s):  
Finite Element ◽  
Contact Problems ◽  
Finite Element Approach ◽  
Nonlinear Contact ◽  
Element Approach

Verification of Mainframe Computer Structure Finite Element Model Under Vibration and Seismic Tests

2018 ◽  
Author(s):  
Budy Notohardjono ◽  
Shawn Canfield ◽  
Suraush Khambati ◽  
Richard Ecker
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Frame Structure ◽  
Element Analysis ◽  
Physical Test ◽  
Design Cycle ◽  
Nonlinear Contact ◽  
The Finite Element Model ◽  
Sine Sweep

Shorter development design schedules and increasingly dense product designs create difficult challenges in predicting structural performance of a mainframe computer’s structure. To meet certain certification benchmarks such as the Telcordia Technologies Generic Requirements GR-63-CORE seismic zone 4 test profile, a physical test is conducted. This test will occur at an external location at the end of design cycle on a fully functional and loaded mainframe system. The ability to accurately predict the structural performance of a mainframe computer early in the design cycle is critical in shortening its development time. This paper discusses an improved method to verify the finite element analysis results predicting the performance of the mainframe computer’s structure long before the physical test is conducted. Sine sweep and random vibration tests were conducted on the frame structure but due to a limitation of the in-house test capability, only a lightly loaded structure can be tested. Evaluating a structure’s modal stiffness is key to achieving good correlation between a finite element (FE) model and the physical system. This is typically achieved by running an implicit modal analysis in a finite element solver and comparing it to the peak frequencies obtained during physical testing using a sine sweep input. However, a linear, implicit analysis has its limitations. Namely, the inability to assess the internal, nonlinear contact between parts. Thus, a linear implicit analysis may be a good approximation for a single body but not accurate when examining an assembly of bodies where the interaction (nonlinear contact) between the bodies is of significance. In the case of a nonlinear assembly of bodies, one cannot effectively correlate between the test and a linear, implicit finite element model. This paper explores a nonlinear, explicit analysis method of evaluating a structure’s modal stiffness by subjecting the finite element model to a vibration waveform and thereafter post processing its resultant acceleration using Fast Fourier Transformation (FFT) to derive the peak frequencies. This result, which takes into account the nonlinear internal contact between the various parts of the assembly, is in line with the way physical test values are obtained. This is an improved method of verification for comparing sine sweep test data and finite element analysis results. The final verification of the finite element model will be a successful physical seismic test. The tests involve extensive sequential, uniaxial earthquake testing in both raised floor and non-raised floor environments in all three directions. Time domain acceleration at the top of the frame structure will be recorded and compared to the finite element model. Matching the frequency content of these accelerations will be proof of the accuracy of the finite element model. Comparative analysis of the physical test and the modeling results will be used to refine the mainframe’s structural elements for improved dynamic response in the final physical certification test.

scholarly journals Finite Element Simulation of the Thermo-mechanical Response of Graphene Reinforced Nanocomposites

2018 ◽  
Vol 188 ◽  
pp. 01016
Author(s):  
Androniki S. Tsiamaki ◽  
Nick K. Anifantis
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Matrix Material ◽  
Continuum Theory ◽  
Element Model ◽  
Multilayer Graphene ◽  
Temperature Changes ◽  
The Matrix

The research for new materials that can withstand extreme temperatures and present good mechanical behavior is of great importance. The interest is highly focused on the utilization of composites reinforced by nanomaterials. To cope with this goal the present work studies the mechanical response of graphene reinforced nanocomposite structures subjected to temperature changes. A computational finite element model has been developed that accounts for both the reinforcement and the matrix material phases. The model developed is based on both the continuum theory and the molecular mechanics theory, for the simulation of the three different material phases of the composite, respectively, i.e. the matrix, the intermediate transition phase and the reinforcement. Considering this model, the mechanical response of an appropriate representative volume element of the nanocomposite is simulated under various temperature changes. The study involves different types of reinforcement composed from either monolayer or multilayer graphene sheets. Apart from the investigation of the behavior of a nanocomposite with each particular type of the reinforcement, comparisons are also presented between them in order to reveal optimized material combinations. The principal parameters taken into consideration, which contribute also to the mechanical behavior of the nanocomposite, are its size, the sheet multiplicity as well as the volume fraction.

An Analysis of Thermo-Mechanical Behavior in a Multilayer Composite Pipe Under Temperature Variation

2010 ◽  
Author(s):  
Wei Yang ◽  
Jyhwen Wang
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Analytical Solution ◽  
Mechanical Behavior ◽  
Temperature Change ◽  
Thermal Stresses ◽  
Element Model ◽  
Functionally Graded ◽  
Element Analysis ◽  
Graded Materials

A generalized analytical solution of mechanical and thermal induced stresses in a multi-layer composite cylinder is presented. Based on the compatibility condition at the interfaces, an explicit solution of mechanical stress due to inner and outer surface pressures and thermal stress due to temperature change is derived. A finite element model is also developed to provide the comparison with the analytical solution. It was found that the analytical solutions are in good agreement with finite element analysis result. The analytical solution shows the non-linear dependency of thermal stress on the diameters, thicknesses and the material properties of the layers. It is also shown that the radial and circumferential thermal stresses depend linearly on the coefficients of thermal expansion of the materials and the temperature change. As demonstrated, this solution can also be applied to analyze the thermo-mechanical behavior of pipes coated with functionally graded materials.

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