Finite Element Model Of Disc Research Articles

Thermal stress simulation and fatigue life of commercial vehicle disk brakes under emergency braking conditions

Commercial vehicle disk brakes operate at a high-temperature and in a heavy-load environment within the braking system. The primary cause of failure is the cracking of the brake disk. In order to study its fatigue damage and service life, a finite element model of disk brake fatigue life was established, and thermal stress coupling simulation analysis was carried out from a practical problem. Based on the temperature and stress fields of the brake disk under emergency braking conditions obtained from the simulation results, the effects of vehicle load, initial speed, temperature, and other factors on brake fatigue life are explored. The fatigue life of the hazardous node can be calculated using the Manson–Coffin model, and then the strain–life (ɛ–N) curve of the material can be fit at high temperature. The fatigue life of brake disks was predicted using the fatigue analysis software FE-SAFE and verified by testing. The results showed that the maximum stress on the surface of the disk brake was the same as the area of the minimum fatigue life, accurately analyzing the fatigue life of the region and predicting the location of fatigue cracks. The results of the research can provide a reference for the design of disk brake engineering and fatigue failure.

Research on Contact Pressure Distribution of Pad

A simplified thermo-structural coupling finite element model of disc brake was developed. The contact pressure distribution of new pad was simulated under an emergency braking condition. The result shows that the contact pressure distribution of pad is not uniform when the new pad is in normal working condition. The inhomogeneity of the contact pressure is a critical cause of tangential partial wear. Compared the contact pressure distribution of new pad, uniform wear pad and tangential partial wear pad, the influence of wear amount and tangential partial wear on the contact pressure of pad was investigated. The results prove that the influence of wear amount on the contact pressure of pad is very small, while tangential partial wear has a great influence on the contact pressure of pad. The wear and force characteristics of pad are analyzed. The wear of its life cycle of pad is obtained, and the reliability and accuracy of the simulation are verified.

Squeal simulation and analysis of brake system with pressure and speed dependent friction model and exerting process of pressure

In this paper, a complete finite element model of disc brake considering the ventilated brake disc, pads, back-plate, caliper, bracket, piston, rubber bushes and simplified fluid model driving piston is established. The pressure and speed dependent friction model and temperature field are considered. The results of complex eigenvalue analysis (CEA) show consistence with the existing achievements, thus the feasibility of the established model is verified. Subsequently, the transient dynamic analysis of the brake system is carried out for different exerting process of the pressure which represents the operation of different drivers. Besides, the vibration responses of different brake pressure and different speed are also investigated. The evolution process of the stability is studied by time-frequency analysis (STFT method). Both CEA and time-frequency analysis show the squeal tends to appear in the case of high friction coefficient, low speed and low brake pressure. It can also be found that the vibration frequency and its energy are not constant but fluctuate in a certain range. The results of different pressure exerting processes with simplified fluid model driving piston show that vibration response of disc brake not only depends on the value of brake pressure but also depends on the pressure exerting process. It is supposed that brake pressure and rotational speed determine the frequency of squeal while the process of exerting pressure determines the existing duration of brake squeal.

Simulating the sensitivity of cell nutritive environment to composition changes within the intervertebral disc

Altered nutrition in the intervertebral disc affects cell viability and can generate catabolic cascades contributing to extracellular matrix (ECM) degradation. Such degradation is expected to affect couplings between disc mechanics and nutrition, contributing to accelerate degenerative processes. However, the relation of ECM changes to major biophysical events within the loaded disc remains unclear. A L4-L5 disc finite element model including the nucleus (NP), annulus (AF) and endplates was used and coupled to a transport-cell viability model. Solute concentrations and cell viability were evaluated along the mid-sagittal plane path. A design of experiment (DOE) was performed. DOE parameters corresponded to AF and NP biochemical tissue measurements in discs with different degeneration grades. Cell viability was not affected by any parameter combinations defined. Nonetheless, the initial water content was the parameter that affected the most the solute contents, especially glucose. Calculations showed that altered NP composition could negatively affect AF cell nutrition. Results suggested that AF and NP tissue degeneration are not critical to nutrition-related cell viability at early-stage of disc degeneration. However, small ECM degenerative changes may alter significantly disc nutrition under mechanical loads. Coupling disc mechano-transport simulations and enzyme expression studies could allow identifying spatiotemporal sequences related to tissue catabolism.

Effects of Young's Modulus on Disc Brake Squeal using Finite Element Analysis

This paper is concerned with the disc brake squeal problem of passenger cars. The objective of this study is to develop a finite element model of the disc brake assembly in order to improve the understanding of the influence of Young’s modulus on squeal generation. A detailed finite element model of the whole disc brake assembly that integrates the wheel hub and steering knuckle is developed and validated by using experimental modal analysis. Stability analysis of the disc brake assembly is conducted to find unstable frequencies. A parametric study is carried out to look into the effect of changing Young’s modulus of each brake’s components on squeal generation. The simulation results indicate that Young’s modulus of the disc brake components plays an important role in generating the squeal noise.

Validation and application of an intervertebral disc finite element model utilizing independently constructed tissue-level constitutive formulations that are nonlinear, anisotropic, and time-dependent

Finite element (FE) models are advantageous in the study of intervertebral disc mechanics as the stress–strain distributions can be determined throughout the tissue and the applied loading and material properties can be controlled and modified. However, the complicated nature of the disc presents a challenge in developing an accurate and predictive disc model, which has led to limitations in FE geometry, material constitutive models and properties, and model validation. The objective of this study was to develop a new FE model of the intervertebral disc, to validate the model׳s nonlinear and time-dependent responses without tuning or calibration, and to evaluate the effect of changes in nucleus pulposus (NP), cartilaginous endplate (CEP), and annulus fibrosus (AF) material properties on the disc mechanical response. The new FE disc model utilized an analytically-based geometry. The model was created from the mean shape of human L4/L5 discs, measured from high-resolution 3D MR images and averaged using signed distance functions. Structural hyperelastic constitutive models were used in conjunction with biphasic-swelling theory to obtain material properties from recent tissue tests in confined compression and uniaxial tension. The FE disc model predictions fit within the experimental range (mean±95% confidence interval) of the disc׳s nonlinear response for compressive slow loading ramp, creep, and stress-relaxation simulations. Changes in NP and CEP properties affected the neutral-zone displacement but had little effect on the final stiffness during slow-ramp compression loading. These results highlight the need to validate FE models using the disc׳s full nonlinear response in multiple loading scenarios.

Temperature Analysis of Disc Brake Based on Parameters Fluctuation

Based on three-dimensional models of key components, a thermoelastic finite element model of disc brake is established. The results of stress field and temperature distribution are acquired considering the relationship of heat convection coefficient and wheel angular velocity. The effect of heat convection coefficient fluctuation and disc material conductivity fluctuation on the model output is analyzed. The simulation results shows that disc temperature is not sensitive to heat convection coefficient, but sensitive to thermal conductivity. And this model mentioned in this paper is of great significant for building a temperature finite element model with engineering accuracy.

Disk Brake Element Chatter Analysis and Strength Evaluation for Railway Vehicle System

Friction brake is still an absolutely necessary way of brake in high speed vehicle today. Complex nonlinear vibration phenomena appear in friction brake system because of dry friction between friction pairs. The resulted brake squeal and brake chatter may cause strength failure and fatigue damage of the disk brake element. Therefore, it is necessary to consider chatter in strength calculation and structure life prediction of disk brake element. In this paper, the finite element model of disk brake element is built. Vibration displacements and dynamic stresses are calculated for chatter character analysis and strength evaluation.

F-0806 変性椎間板の力学特性を考慮した脊椎分離辷り症の有限要素解析(S43-2 3次元画像・モデルによる生体力学シミュレーション)(S43 生体力学シミュレーション)

This study is concerned with the mechanical causes of isthmic spondylolisthesis. The effects of disc degeneration on instability of isthmic defect vertebrae are discussed by using finite element analyses. The finite element model of disc is refined based on the model used in former study. Disc degeneration is modeled as a change of mechanical properties of annulus fibrosus. The results of flexion motion analyses show that the percentage of slipping is decreased by the change of mechanical properties of disc however the decrease of instability is not significant quantitatively. As slip angle is significantly increased, it may cause an initial damage of tissue in the disc.

A simplified intervertebral disc finite-element model with a fiber-composite annulus

A simplified intervertebral disc finite-element model with a fiber-composite annulus