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Journal Article

A Road Load Data Processing Technique for Durability Optimization of Automotive Products

Durability of a product is related to three major factors, the load, structure and material. The durability performance of an automotive product is, therefore, not only depended on the structure configuration, but also on the road load dynamic characteristics (profiles and frequency spectrum), and the material fatigue properties as well. Due to the dynamic nature of vehicle loads, one of the major technical challenges, to the durability design optimization of automotive products, is how to define a set of representative road loads, for fidelity and efficiency, based on the measured proving ground durability data of huge size. This paper presents a procedure of processing the proving ground road loads, for vehicle durability design and optimization of automotive products, based on the statistical characteristics evaluation and fatigue damage equivalency techniques.
Technical Paper

Accelerated Tests of Wiper Motor Retainers Using CAE Durability and Reliability Techniques

An accelerated test procedure has been developed at Visteon to reduce the component durability test time, while meeting the reliability requirements. The method and procedure are presented in this paper with application examples to wiper motor bearing retainers. The new test speed, load level, and test duration of the accelerated test are derived by employing the CAE durability and reliability techniques. The accelerated test speed is determined based on the dynamic characteristics of the test specimen-fixture-machine system, using the CAE finite element analysis method. The increased test load level is obtained based on CAE dynamic stress simulation, material fatigue model, and durability damage equivalence. The reduced test duration (or number of test cycles) is determined based on CAE equivalent fatigue damage technique and modified from the reliability requirement parameters, such as reliability target, confidence level, and sample size.
Journal Article

Automotive Structural Durability Design Using Dynamic Simulation and Fatigue Damage Sensitivity Techniques

It is well known that product durability is related to three major factors, the structure, load and material. That is, the durability performance of an automotive product is not only depended on the structure configuration, but also related to the load dynamic characteristics (such as, profiles and frequency spectrum), and the material fatigue properties as well. Due to the fact that the automotive vehicle loads are dynamic in nature, one of the major technical challenges to the product durability design is how to quantify the fatigue damage sensitivity. This paper presents a procedure of automotive structural design for durability performance based on the structural dynamic simulation and fatigue damage sensitivity techniques. A methodology for calculating the fatigue damage sensitivity is introduced.
Technical Paper

CAE Virtual Design Validation Tests of Automotive Engine Mount Systems

This paper presents a CAE virtual test procedure for automotive engine mount systems, which evaluates NVH and durability performance of an engine suspension design. Engine mount systems are virtually tested in terms of noise and vibration response characteristics, mount structural strength and fatigue durability, under the defined engine load conditions. The proposed procedure incorporates several CAE modeling and simulation technologies, including the definition of engine test loading environment, the modeling of nonlinear rubber bushings for their stiffness and damping properties, the frequency domain dynamic simulation, and fatigue damage prediction technologies. First, the test engine load specifications are defined from the measured engine vibration raw data with respect to engine speeds, and the engine speed duty cycle statistics.
Technical Paper

CAE Virtual Door Slam Test for Plastic Trim Components

Visteon has developed a CAE procedure to qualify plastic door trim assemblies under the vehicle door slam Key Life Test (KLT) environments. The CAE Virtual Door Slam Test (VDST) procedure simulates the environment of a whole door structural assembly, as a hinged in-vehicle door slam configuration. It predicts the durability life of a plastic door trim sub-assembly, in terms of the number of slam cycles, based on the simulated stresses and plastic material fatigue damage model, at each critical location. The basic theory, FEA methods and techniques employed by the VDST procedure are briefly described in this paper. Door trim project examples are presented to illustrate the practical applications and their results, as well as the correlation with the physical door slam KLTs.
Journal Article

CAE Virtual Durability Tests of Automotive Products in the Frequency Domain

Both NVH and durability performance of automotive products are mainly related to their structural frequency characteristics, such as their resonant frequencies, normal modes, stiffness and damping, and transfer function properties. During the automotive product development, product design validation test loads for NVH and durability are, therefore, often specified in the frequency domain, in terms of either swept sinusoidal vibration or random vibration in power spectral density function. This paper presents a procedure of CAE virtual design validation tests for durability evaluation due to the frequency domain vibration test loads. A set of frequency domain simulation techniques and durability evaluation methodologies, for material fatigue damage due to either random or sinusoidal vibration loads, are introduced as well.
Technical Paper

CAE Virtual Test of Air Intake Manifolds Using Coupled Vibration and Pressure Pulsation Loads

A coupled vibration and pressure loading procedure has been developed to perform a CAE virtual test for engine air intake manifolds. The CAE virtual test simulates the same physical test configuration and environments, such as the base acceleration vibration excitation and pressure pulsation loads, as well as temperature conditions, for design validation (DV) test of air intake manifolds. The original vibration and pressure load data, measured with respect to the engine speed rpm, are first converted to their respective vibration and pressure power spectrum density (PSD) profiles in frequency domain, based on the duty cycle specification. The final accelerated vibration excitation and pressure PSD load profiles for design validation are derived based on the key life test (KLT) duration and reliability requirements, using the equivalent fatigue damage technique.
Technical Paper

Localized Nonlinear Model of Plastic Air Induction Systems for Virtual Design Validation Tests

Plastic air induction system (AIS) has been widely used in vehicle powertrain applications for reduced weight, cost, and improved engine performance. Physical design validation (DV) tests of an AIS, as to meet durability and reliability requirements, are usually conducted by employing the frequency domain vibration tests, either sine sweep or random vibration excitations, with a temperature cycling range typically from -40°C to 120°C. It is well known that under high vibration loading and large temperature range, the plastic components of the AIS demonstrate much higher nonlinear response behaviors as compared with metal products. In order to implement a virtual test for plastic AIS products, a practical procedure to model a nonlinear system and to simulate the frequency response of the system, is crucial. The challenge is to model the plastic AIS assembly as a function of loads and temperatures, and to evaluate the dynamic response and fatigue life in frequency domain as well.