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>

Research on Friction between Grade Flat Approach Slab and Sliding Material in Jointless Bridges

2019 ◽  
Author(s):  
Yufeng Tang ◽  
Bruno Briseghella ◽  
Junqing Xue ◽  
Peiquan Zhang ◽  
Fuyun Huang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Life Cycle Cost ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Element Model ◽  
Expansion Joints ◽  
Approach Slab ◽  
Jointless Bridges ◽  
Friction Function ◽  
The Mathematical Model

<p>The application of jointless bridges has been increasing year by year, because it could reduce the life‐cycle cost and improve the riding comfort. The approach slab in jointless bridges does not only have the function of road transition which is the same as the approach slab in bridges with expansion joints, but also transfer and absorb the deformation produced by the thermal expansion and contraction of the girder. The Grade Flat Approach Slab (GFAS) horizontally placed on the subgrade is one of the most common types of the approach slab in jointless bridges. The material placed between GFAS and subgrade should be able to properly slide to reduce the stress in GFAS. The friction coefficient between GFAS and sliding material is an important parameter affecting the mechanical behavior of GFAS in jointless bridges. In this paper, the tests of GFAS with different sliding materials subjected to horizontal displacement were conducted to obtain the corresponding friction coefficients (from 0.34 to 0.68). The mathematical model of bilinear spring could be adapted to simulate the friction function between GFAS and different sliding materials. One Deck‐Extension Bridge (DEB) that is one type of jointless bridges was chosen as a case study. The finite element model was implemented by using Midas‐Civil software. The influence of GFAS with different sliding materials on the mechanical properties of DEB under temperature variation was investigated. It can be concluded that the influence of the friction coefficient between GFAS and sliding material on the bending moment of DEB should be taken into account.</p>

scholarly journals Research on the longitudinal mechanical behaviours of subway turnouts of large slope under train braking force

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110283
Author(s):  
Zhiping Zeng ◽  
Ji Hu ◽  
Chunyu Tian ◽  
Ping Li ◽  
Xiangdong Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Change ◽  
Mechanical Characteristics ◽  
Element Model ◽  
Longitudinal Displacement ◽  
Longitudinal Deformation ◽  
Longitudinal Stiffness ◽  
Mechanical Behaviours ◽  
Longitudinal Resistance ◽  
Safety And Stability

To study subway turnouts’ adaptability to steep gradients, a finite element model of a metro No. 9 simple turnout was established. The main works include: (1) The train’s most unfavourable loading condition was modelled. (2) The turnout’s longitudinal displacement and stress were analysed with different gradients under the train braking load, temperature change load and a combination of the two, to determine the structure’s safety and stability under the most unfavourable working conditions. (3) The turnout structure’s cumulative longitudinal deformation under reciprocating load was studied. Both a fastener longitudinal resistance-displacement experiment under reciprocating load and a numerical simulation of No. 9 turnout modelled by the finite element modelling software, ANSYS, were carried out to study the gradient’s influence on the turnout’s longitudinal mechanical characteristics. (1) The turnout’s longitudinal displacement and stress increase linearly with an increase in gradient and temperature change, both of which are unfavourable to the turnout structure. As the gradient increases from 0‰ to 30‰, the longitudinal stress and displacement increase by more than 10%. (2) The turnout’s rail strength and displacement on a 30‰ slope under the most unfavourable load conditions are within the specification limitations. (3) Under reciprocating load, the fastener longitudinal stiffness decreases and the maximum and residual longitudinal displacement of the switch rail increase; an increased gradient intensifies these effects on the turnout.

Design and Performance of Jointless Bridges in Ontario: New Technical and Material Concepts

2000 ◽  
Vol 1696 (1) ◽  
pp. 109-121 ◽  
Author(s):  
Iqbal Husain ◽  
Dino Bagnariol
Keyword(s):  
Economic Benefits ◽  
Integral Abutment ◽  
Expansion Joints ◽  
Actual Performance ◽  
Approach Slabs ◽  
Approach Slab ◽  
Jointless Bridges ◽  
Integral Abutment Bridge ◽  
Existing Bridges ◽  
Deck Slab

It is well recognized that leaking expansion joints at the ends of bridge decks have led to the premature deterioration of bridge components. The elimination of these maintenance-prone joints not only yields immediate economic benefits but also improves the long-term durability of bridges. In Ontario, Canada, “jointless” bridges have been used for many years. Recently, the use of two main types of these bridges has increased dramatically. The first type is an “integral abutment” bridge that comprises an integral deck and abutment system supported on flexible piles. The approach slabs are also continuous with the deck slab. The flexible foundation allows the anticipated deck movements to take place at the end of the approach slab. Control joint details have been developed to allow movements at this location. The second type is a “semi-integral abutment” bridge that also allows expansion joints to be eliminated from the end of the bridge deck. The approach slabs are continuous with the deck slab, and the abutments are supported on rigid foundations (spread footings). The superstructure is not continuous with the abutments, and conventional bearings are used to allow horizontal movements between the deck and the abutments. A control joint is provided at the end of the approach slab that is detailed to slide in between the wing walls. Some of the design methods and construction details that are used in Ontario for integral and semi-integral abutment bridges are summarized. A review of the actual performance of existing bridges is also presented.

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.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2018 ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Volkan Coşkun ◽  
Bülent Acar ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Layer Thickness ◽  
Pressure Vessel ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture the pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition and material properties of matrix and fiber. The designed ideal pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, the effect of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance was investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the layer-by-layer thickness and fiber volume fraction variation. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization test was performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

Experimental Investigation and Elastic-Plastic Analysis on Connection Strength of Zirconium Tube-Tubesheet Joints

2008 ◽  
Vol 44-46 ◽  
pp. 529-536
Author(s):  
Biao Yuan ◽  
Y.Z. Wang ◽  
X. Ma ◽  
Yang Yan Zheng ◽  
Shan Tung Tu
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Element Model ◽  
Connection Strength ◽  
Element Analysis ◽  
Petrochemical Process ◽  
Expansion Joints ◽  
Pull Out ◽  
Significant Difference ◽  
Zirconium Tube

Zirconium tube is widely used in heat exchanger equipments in petrochemical process for significant corrosion resistance. The connection joint of tube-tubesheet is the weakest parts in a heat exchanger. The experiment and numerical analysis of different materials (zirconium tubes, titanium tubes and 16MnR tubesheets, 316L tubesheet) joints were performed in this paper. The expansion joints specimens were prepared at the pressure ranging from 28MPa to 38MPa. And pulling out test was performed from 20°C to 300°C. The finite element model of tube-tubesheet joint was established. The effect of expansion pressure, temperature and groove on the pulling out strength of joints was analyzed. Both the experiments and the finite element analysis show that the pull-out strength increases with the increasing expansion pressures. Working temperature also has a great effect on the connection strength of tube-to-tubesheet joints, especially for the zirconium and 316L joints, which have the most significant difference of thermal expansion coefficient between tube and tubesheet. The residual contacting pressure on the contact surface between tubes and the tubesheet is not uniformly distributed and two tightness bands are found near the surfaces of the tubesheet or at the two brinks of the groove on the tubesheet hole. Compared with the ungrooved joint, the residual contacting pressure on the tightness bands for the grooved joint is much higher, indicating a grooved joint has better tightness.

Finite Element Analysis of Mechanics Property on Memory Alloy Patella Claws with Anti-Shearing Force

2014 ◽  
Vol 635-637 ◽  
pp. 507-510
Author(s):  
Dong Peng Du ◽  
Zhe Wu ◽  
Juan Xing ◽  
Xiao Yan Gong ◽  
Xiang Wen Miu ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Tensile Force ◽  
Research Result ◽  
Element Model ◽  
3D Models ◽  
Shearing Force ◽  
Maximum Displacement ◽  
Element Analysis

When strong exercise on human being body, respectively, under knees 30°, 60°,90°, using PRO/E5.0 software to establish the transverse patella fracture and anti-shearing force patella claws 3D models, then the two structure models were assembled and imported into ABAQUS10.1 software to establish the finite element model of patellar fracture fixed within patella claw, and analyzed the mechanical performance in perforce finite element model. Under the same boundary conditions, the maximum displacement and deformation of each components were different at every flexion angle. Compared with anti-shearing force patella claw and AO tensile force girdle, the patella claw with stronger resistance to tension and anti-shearing force was more stable. Deformation and displacement of patella claw in accordance with biomechanical research result that is needed by clinical. Its stability will satisfy clinical requirements for functional exercise.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Bülent Acar ◽  
Volkan Coşkun ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Material Properties ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Abstract Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition, and material properties of matrix and fiber. The designed pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, effects of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance were investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the thickness of each layer separately and variation of fiber volume fraction between the layers. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization tests were performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

Analysis of the crashworthiness design and collision dynamics of a subway train

2019 ◽  
Vol 234 (10) ◽  
pp. 1117-1128
Author(s):  
Suchao Xie ◽  
Xuanjin Du ◽  
Hui Zhou ◽  
Da Wang ◽  
Zhejun Feng
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Mechanical Performance ◽  
Simulation Analysis ◽  
Element Model ◽  
Collision Dynamics ◽  
Element Analysis ◽  
Static Compression ◽  
Subway Train ◽  
Energy Absorbing

In this study, the crashworthiness of a subway train was assessed by establishing a finite element model for the first three carriages of the train and the track using the Hypermesh software. By utilising the *MAT_HONEYCOMB material model, a honeycomb in an anti-climbing energy-absorbing device was simulated. Moreover, the process of a subway train – travelling at a speed of 25 km/h – colliding with another identical train in a stationary and non-braking state was simulated by employing the finite element analysis software Hypermesh and LS-DYNA. The process of simulation analysis was divided into two parts: (1) analysis of the anti-climbing energy-absorbing devices under static compression for the investigation of energy absorption and (2) collision analysis of the whole train. The contributions of the proposed energy-absorbing structure – at the end of driver’s cab, the coupler and draft gears on each section – to the overall energy absorption in a train collision were calculated. Furthermore, based on the EN15227 standard, the crashworthiness of the train with respect to the survival space for occupants, train acceleration and uplift of wheels relative to the track was evaluated. The coupler of the first carriage fails in a collision at 25 km/h, and the coupler and draft gear are the main energy-absorbing devices. *MAT_HONEYCOMB was used to define the honeycomb materials in anti-climbing energy-absorbing devices and could simulate the mechanical performance thereof. The crashworthiness of the train meets the relevant standard requirements.

Sign in / Sign up

Export Citation Format

Share Document