Finite Element Simulation of Steel Quench Distortion- Parametric Analysis of Processing Variables

2012 ◽  
Vol 1485 ◽  
pp. 29-34 ◽  
Author(s):  
F. A. García-Pastor ◽  
R.D. López-García ◽  
E. Alfaro-López ◽  
M. J. Castro-Román
Keyword(s):  
Finite Element ◽  
Martensitic Transformation ◽  
Internal Stress ◽  
Thermal Stresses ◽  
Stress Fields ◽  
Leaf Spring ◽  
Internal Stresses ◽  
Processing Temperature ◽  
Fe Model ◽  
Slow Cooling

ABSTRACTSteel quenching from the austenite region is a widely used industrial process to increase strength and hardness through the martensitic transformation. It is well known, however, that it is very likely that macroscopic distortion occurs during the quenching process. This distortion is caused by the rapidly varying internal stress fields, which may change sign between tension and compression several times during quenching. If the maximum internal stress is greater than the yield stress at given processing temperature, plastic deformation will occur and, depending on its magnitude, macroscopic distortion may become apparent.The complex interaction between thermal contraction and the expansion resulting from the martensitic transformation is behind the sign changes in the internal stress fields. Variations in the steel composition and cooling rate will result in a number of different paths, which the internal stresses will follow during processing. Depending on the route followed, the martensitic transformation may hinder the thermal stresses evolution to the point where the stress fields throughout the component may actually be reverted. A different path may support the thermal stresses evolution further increasing their magnitude. The cross-sectional area also affects the internal stresses magnitude, since smaller areas will have further trouble to accommodate stress, thus increasing the distortion. Additionally, the bainitic transformation occurring during relatively slow cooling rates may have an important effect in the final stress field state.A finite-element (FE) model of steel quenching has been developed in the DEFORM 3D simulation environment. This model has taken into account the kinetics of both austenite-bainite and austenite-martensite transformations in a simplified leaf spring geometry. The results are discussed in terms of the optimal processing parameters obtained by the simulation against the limitations in current industrial practice.

A Coupled Multibody Finite Element Model for Investigating Effects of Surface Defects on Rolling Contact Fatigue

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Zamzam Golmohammadi ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Surface Defects ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Internal Stresses ◽  
Fe Model ◽  
Elastic Plastic ◽  
Pile Up

A coupled multibody elastic–plastic finite element (FE) model was developed to investigate the effects of surface defects, such as dents on rolling contact fatigue (RCF). The coupled Voronoi FE model was used to determine the contact pressure acting over the surface defect, internal stresses, damage, etc. In order to determine the shape of a dent and material pile up during the over rolling process, a rigid indenter was pressed against an elastic plastic semi-infinite domain. Continuum damage mechanics (CDM) was used to account for material degradation during RCF. Using CDM, spall initiation and propagation in a line contact was modeled and investigated. A parametric study using the model was performed to examine the effects of dent sharpness, pile up ratio, and applied load on the spall formation and fatigue life. The spall patterns were found to be consistent with experimental observations from the open literature. Moreover, the results demonstrated that the dent shape and sharpness had a significant effect on pressure and thus fatigue life. Higher dent sharpness ratios significantly reduced the fatigue life.

scholarly journals FINITE ELEMENT ANALYSIS OF THE HEAT TRANSFER IN A PISTON

2020 ◽  
Vol 4 (1) ◽  
pp. 45-51
Author(s):  
Aisha Muhammad ◽  
Shanono Ibrahim Haruna
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Numerical Simulations ◽  
Internal Combustion Engines ◽  
Thermal Stresses ◽  
Maximum Temperature ◽  
Cylinder Wall ◽  
Fe Model ◽  
Piston Cylinder ◽  
Piston Head

The gas expansion process that takes place in a piston cylinder assembly have been used in numerous applications. However, the time-dependent process of heat transfer is still not fully apprehended as the expansion processes are complex and difficult due to the unsteady property of the turbulent flow process. Internal combustion Engines(ICE) designs are conducted with the aim of achieving higher efficiency in the thermal characteristics. To optimize these designs, numerical simulations are conducted. However, modelling of the process in terms of heat transfer and combustion is complex and challenging. For a designer to understand, calculate and quantify the thermal stresses and heat losses at different sections of the structure, understanding the piston-cylinder wall is needed. This study carried out a numerical simulations based on Finite Element Method (FEM) to investigatethe stresses in the piston, and temperature after loading. Appropriate boundary conditions were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, cylinder wall, and connecting rod. Results show the maximum Von-misses stress occurs on the piston head with a value of 3486. 1MPa. The maximum temperature of the piston head and cylinder wall stands at 68.252 and 42.704 degree Celsius respectively.

Adjusting of Roller Levellers by Finite Element Simulations Including a Closed-Loop Control

2014 ◽  
Vol 1018 ◽  
pp. 207-214 ◽  
Author(s):  
Markus Grüber ◽  
Marius Oligschläger ◽  
Gerhard Hirt
Keyword(s):  
Finite Element ◽  
Closed Loop ◽  
Sheet Material ◽  
Numerical Approach ◽  
Internal Stresses ◽  
Closed Loop Control ◽  
Fe Model ◽  
Production Chain ◽  
Loop Control ◽  
Curvature Measurement

Within today’s sheet processing lines, roller levellers are included in the production chain to eliminate initial curvature and reduce internal stresses of the sheet material. Despite the desire to achieve fully automated industrial processes, roller levellers still have to be set manually by an operator based on his experience and empirical data. Therefore, this paper evaluates an enhanced numerical approach to predict the vertical roll position, the so called roll intermesh, in the last load triangle. To gain the respective machine setting, a closed-loop control based on an actual curvature measurement is implemented in the finite element (FE) programme Abaqus utilising a user-subroutine. Thus, the presented FE model allows the adjustment of the roller leveller leading to a flat strip in a single simulation run within the accuracy of the FE prediction. Additionally, the FE model provides the chance to develop and test closed-loop controls for roller levelling. Complementing the results gained from the FE model, experiments have been conducted on a down-sized roller leveller with aluminium sheets (AA5005). First results obtained with the presented numerical model proved that the roll intermesh of the last load triangle was determined successfully and the use of an actual curvature measurement within the FE model provides enhanced accuracy.

Object-Oriented Environment for Dynamic Finite Element Modeling of Tires and Suspension Systems

2006 ◽  
Author(s):  
Tamer M. Wasfy ◽  
Hatem Wasfy
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Time History ◽  
Object Oriented ◽  
Rigid Bodies ◽  
Leaf Spring ◽  
Fe Model ◽  
Suspension Systems ◽  
Preliminary Model ◽  
Time Histories

An object-oriented graphical modeling environment, which includes integrated pre-processor, post-processor, and explicit time-integration finite element solver, for predicting the dynamic response of tires mounted on suspension systems is described. The pre-processor allows creating a hierarchical preliminary model of the system including the tire, suspension system, and terrain. The pre-processor includes an automatic mesh generator for generating the finite element (FE) model from the preliminary model. A tire preliminary object allows defining the tire cross-section, specifying the number of elements along the tire circumference, and defining beam elements along the circumference and meridian direction to model the various tire structural components such as the bead, ply, and belt. Other preliminary model objects include rigid body, linear spring-damper, leaf-spring, spherical joint, revolute joint, prismatic joint, and polygonal terrain. The user can also include support objects such as physical materials, and scalar graphs (for time-histories of known quantities). The preprocessor includes a model tree-editor which allows adding objects and changing their properties. The FE model is submitted to the solver which generates the system's motion time-history. The FE model consists of solid elements (including brick, beam, and truss), rigid bodies, and joints. The post-processor is used to display the analysis results, which include an animation of the motion of the system, coloring/contouring the tire using various scalar response quantities, and various types of graphs of response quantities (such as time-history, frequency and time-averaged graphs). The graphical output of the pre-processor and the post-processor can be displayed either on the computer screen or in immersive stereoscopic virtual-reality facilities. Users can control the visualization using the tree-editor.

FINITE ELEMENT PREDICTION OF SUB-DERMAL TISSUE STRESSES OF THE BUTTOCKS DURING WHEELCHAIR PROPULSION

2016 ◽  
Vol 16 (04) ◽  
pp. 1650058
Author(s):  
SUJIAO LI ◽  
MIN YIN ◽  
LIN GAO ◽  
SHUN QI ◽  
JUE WANG
Keyword(s):  
Finite Element ◽  
Pressure Ulcers ◽  
Tissue Injury ◽  
Movement Speed ◽  
Internal Stresses ◽  
Fe Model ◽  
Wheelchair Propulsion ◽  
Deep Tissue Injury ◽  
Dermal Tissue ◽  
Peak Pressures

Pressure ulcers, involving sub-dermal tissue damage and originating in deep tissue injury (DTI), have attracted much attention of physicians and researchers for three decades. Finite element (FE) model is a very efficient tool to investigate internal stresses and strains in human body that induce pressure ulcers. However, there was scarce report available to explore stresses distribution in human buttocks during manual wheelchair propulsion. A three-dimensional (3D) comprehensive FE model, incorporating ischial tuberosities (ITs), muscle, fat, and custom-contoured cushion (CCC), was developed to investigate internal stress distribution in soft tissue of the buttocks. Based on the FE model, pressure distribution under ITs in static sitting and during different wheelchair propulsions is studied. Internal stresses in fat and muscle were about three times and five times higher than that on cushion surface in terms of static sitting and wheelchair propulsion. All peak pressures under wheelchair propulsion were higher than those of static sitting, and peak pressures went on increasing with increase of wheelchair movement speed. This method based on the comprehensive FE model allowed for the optimization of wheelchair seat cushion design.

A NEW CUSTOM-CONTOURED CUSHION SYSTEM BASED ON FINITE ELEMENT MODELING PREDICTION

2013 ◽  
Vol 13 (04) ◽  
pp. 1350051 ◽  
Author(s):  
SUJIAO LI ◽  
ZHENGXIANG ZHANG ◽  
JUE WANG
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Internal Stress ◽  
Soft Tissues ◽  
Spinal Cord Injuries ◽  
Clinical Performance ◽  
Three Dimensional ◽  
Fe Model ◽  
Interface Pressure ◽  
Modeling Prediction

High internal stress in the deep tissues adjacent to bony prominences can cause deep tissue injuries. Therefore, internal stress in the soft tissue should be considered when the performance of anti-decubitus cushions is evaluated during cushion design. This paper reports on a custom-contoured cushion (CCC) system incorporated with a three-dimensional (3D) slice subject-specific finite element (FE) model to investigate the internal stress distribution in the soft tissues. This stress distribution was used to transform the interface pressure into the carving depth of the fabricated cushions based on the biomechanical characteristics of the cushion materials. The internal stress in the soft tissues was investigated using an FE model of buttocks and cushion made from three cushion materials. The cushion design was optimized according to the properties of the material. The simulated interface stress between the buttocks and the cushion (18 kPa) was consistent with the measured interface pressure of the CCC (17.1 kPa). The 3D FE model predicted the internal stress and displacement of the soft tissues and cushion. Additionally, it efficiently optimized the selection of cushion material. Fifty subjects (25 subjects with spinal cord injuries (SCI) and 25 healthy subjects) were recruited to investigate the interface pressure and perform subjective comfort evaluation. The CCC decreased the interface pressure under the buttocks and simultaneously increased the subjective comfort and stability. The effectiveness of the cushion materials was predicted by the CCC system, which also validated the clinical performance of decreasing interface pressure.

Modeling and Analysis of Weld Geometries, Size and Gap on Weld-Induced Thermal Stresses in a Solid Round-on-Flat Plate Fillet Weld

2017 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay ◽  
Haider Al-Mamoury
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Stresses ◽  
Rapid Heating ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Fe Model ◽  
Fillet Weld ◽  
Modeling And Analysis

In this paper a finite element model is presented which describes the effects of fillet weld geometry on the thermal stresses. In a separate research, development of a finite element model for simulating welding-induced thermal stresses is discussed. This nonlinear FE model employs fully coupled three-dimensional thermo-mechanical formulation, including interfacial element to simulate the weaker solidified molten weld pool. Due to the nature of the welding process, heat generation from moving heat source, rapid heating and cooling gives rise to high stresses in the weld. This research investigates the effect of weld shape & size, weld gap, (l/d ratio) depth of weld to size ratio on the generated thermal stresses. The size of the round and flat stocks has been varied to investigate their effects of the stresses as well as to determine the thick-to-thin geometry limits based on acceptable design limits of thermal stresses.

scholarly journals A Combination of Finite Difference and Finite Element Methods for Temperature and Stress Predictions of Early-Age Concrete Members

2020 ◽  
Author(s):  
Tu Anh Do
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Finite Element Methods ◽  
Thermal Stresses ◽  
Early Age ◽  
Fe Model ◽  
Thermally Induced ◽  
Temperature Changes ◽  
Concrete Members ◽  
Early Age Concrete

A combination of finite difference and finite element methods was employed to develop a model for predicting the temperature development and thermally induced stresses in early-age concrete members (such as bridge footings, piers, columns, girders, and slabs). A two-dimensional finite difference (FD) scheme was utilized for heat generation and transfer within a hydrating concrete member. A finite element (FE) plane strain model was then established to compute the thermal stresses in the concrete subjected to the temperature changes. The FD-FE model can be easily created using any programing language, and the methodology can be used to predict the temperatures and stresses as well as assess the possibility of early-age cracking in concrete members.

scholarly journals Structure Design of GFRP Composite Leaf Spring: An Experimental and Finite Element Analysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1193
Author(s):  
Linlin Ma ◽  
Jingwu He ◽  
Yizhuo Gu ◽  
Zuoguang Zhang ◽  
Zechuan Yu ◽  
...  
Keyword(s):  
Finite Element ◽  
Variable Thickness ◽  
Mechanical Performance ◽  
Structure Design ◽  
Filament Winding ◽  
Leaf Spring ◽  
Material Strength ◽  
Fe Model ◽  
Experimental Sample ◽  
Element Analysis

Due to the high load-bearing capacity and light weight, composite leaf spring with variable width and variable thickness has been increasingly used in the automobile industry to replace the conventional steel leaf spring with a heavy weight. The optimum structural design of composite leaf spring is particularly favorable for the weight reduction. In this study, an effective algorithm is developed for structural optimization of composite leaf spring. The mechanical performance of composite leaf spring with designed dimensions is characterized using a combined experimental and computational approach. Specifically, the composite leaf spring with variable width and variable thickness was prepared using the filament winding process, and the three-dimensional finite element (FE) model of the designed composite leaf spring is developed. The experimental sample and FE model of composite leaf spring are tested under the three-point bending method. From experimental and simulation results, it is shown that the bending stiffness of the designed leaf spring meets the design requirement in the automotive industry, while the results of stress calculation along all directions meet the requirements of material strength requirement. The developed algorithm contributes to the design method for optimizing the stiffness and strength performance of the composite leaf spring.

Stress Field Simulation of Compound Cast Rollers during Centrifugal Casting Process

2012 ◽  
Vol 217-219 ◽  
pp. 1740-1747
Author(s):  
Li Gang Liu ◽  
Hui Yu ◽  
Yu Hui Wang ◽  
Yu Dong Yang ◽  
Cong Tao Liang ◽  
...  
Keyword(s):  
Stress Field ◽  
Internal Stress ◽  
Centrifugal Casting ◽  
Casting Process ◽  
Stress Fields ◽  
Fe Model ◽  
Cooling Process ◽  
Casting Method ◽  
X Ray ◽  
Residual Internal Stress

The stress field of compound cast rollers during centrifugal casting process was investigated in this work. A finite element (FE) model was built to simulate the internal stress fields during cooling process, in which phase transformation was considered. The mechanical parameters employed in stress numerical simulation were measured by using thermal/mechanical simulator. The residual internal stress of the compound cast roller by centrifugal casting method was measured by using X-ray stress analyzer. The simulated results are in agreement with the measured ones very well. According to this model, the temperature and stress fields of the compound cast roller during centrifugal casting process were simulated.

Sign in / Sign up

Export Citation Format

Share Document