The Development, Dynamic Simulation and Verification of a Half-Vehicle Model for Durability Testing

1994 ◽  
Author(s):  
D. A. Belfiore ◽  
B. J. Gilmore ◽  
J. C. Wambold
Keyword(s):  
Dynamic Simulation ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Life Testing ◽  
Life Test ◽  
Vehicle Model ◽  
Transit Buses ◽  
Accelerated Life ◽  
Dynamic Simulation Model ◽  
Durability Testing

Abstract Accelerated life testing analysis for transit buses requires a dynamic simulation model using road profiles as excitation inputs. This paper presents the modeling and parameter estimation required to conduct such a dynamic simulation of a small bus. The simulation preclude the necessity of measuring actual vehicle response traversing portions of selected roads. The results from the simulation correlate well with actual results in both magnitude and frequency distribution and thus, may be used for accelerated life test purposes.

scholarly journals Life Prediction on a T700 Carbon Fiber Reinforced Cylinder with Limited Accelerated Life Testing Data

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Ma Xiaobing ◽  
Zhang Yongbo
Keyword(s):  
Carbon Fiber ◽  
Test Data ◽  
Life Prediction ◽  
Rupture Life ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Life Testing ◽  
Life Test ◽  
Failure Data ◽  
Accelerated Life

An accelerated life testing investigation was conducted on a composite cylinder that consists of aluminum alloy and T700 carbon fiber. The ultimate failure stress predictions of cylinders were obtained by the mixing rule and verified by the blasting static pressure method. Based on the stress prediction of cylinder under working conditions, the constant stress accelerated life test of the cylinder was designed. However, the failure data cannot be sufficiently obtained by the accelerated life test due to the time limitation. Therefore, most of the data presented to be high censored in high stress level and zero-failure data in low stress level. When using the traditional method for rupture life prediction, the results showed to be of lower confidence. In this study, the consistency of failure mechanism for carbon fiber and cylinder was analyzed firstly. According to the analysis result, the statistical test information of carbon fiber could be utilized for the accelerated model constitution. Then, rupture life prediction method for cylinder was proposed based on the accelerated life test data and carbon fiber test data. In this way, the life prediction accuracy of cylinder could be improved obviously, and the results showed that the accuracy of this method increased by 35%.

Analysis of Accelerated Life Test Data Involving Two Failure Modes

2011 ◽  
Vol 211-212 ◽  
pp. 1002-1006 ◽  
Author(s):  
R. Jiang
Keyword(s):  
Shape Parameter ◽  
Failure Modes ◽  
Risk Model ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Life Testing ◽  
Life Test ◽  
Life Distribution ◽  
Accelerated Life ◽  
Step Procedure

This paper presents an approach to analyze accelerated life testing (ALT) data involving two failure modes. The approach first transforms the ALT dataset into two new datasets that correspond to individual failure modes. Each transformed dataset is modeled using a two-step procedure, and the resulted models associated with individual failure modes are combined into a competing risk model. The approach is illustrated using the ALT data of industrial heaters from the literature. The analysis shows that the shape parameter of the life distribution can change with stress level.

A Study on Procedures of the Accelerated Life Testing for Hose Assemblies

2005 ◽  
Vol 297-300 ◽  
pp. 1870-1875
Author(s):  
Y.B. Lee ◽  
Hyoung Eui Kim ◽  
J.H. Park ◽  
J.M. Ko
Keyword(s):  
Accelerated Life Testing ◽  
Test Method ◽  
Life Testing ◽  
Life Test ◽  
Life Distribution ◽  
Burst Test ◽  
Manufacture Process ◽  
Accelerated Life ◽  
Long Time ◽  
Impulse Pressure

There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving ‘Knockdown stress’ to hose assemblies just until before the hose assemblies get out of order.

Highly Accelerated Life Test (HALT) Program at Space Systems Loral

2013 ◽  
Vol 56 (2) ◽  
pp. 1-19
Author(s):  
Brian Kosinski ◽  
Dennis Cronin
Keyword(s):  
New Technologies ◽  
Electronics Industry ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Space Systems ◽  
Life Test ◽  
Test Specifications ◽  
Accelerated Life ◽  
Environmental Test ◽  
Intended Use

Highly Accelerated Life Testing (HALT) is used in the commercial electronics industry to improve product robustness prior to starting production. The basic theory is that testing well beyond expected, intended-use environments may uncover design flaws that could become field failures after a product is in production. By fixing issues prior to starting production, costly recalls can be avoided. HALT has proven to be effective, as evidenced by its wide incorporation in the commercial electronics industry. Could HALT also be worth the time and expense of performing on commercial satellite hardware, which is designed to rigorous standards and tested over military-grade environmental test specifications? This paper summarizes Space Systems/Loral's (SS/L) initial experience with HALT, experience over time, and refinement of the traditional HALT process with emphasis on finding the operating limit margins before purposely searching for any failure limits. The methodology used by SS/L has proven to be effective when introducing new technologies and complex designs for use on commercial satellites.

scholarly journals A Study on Failure Analysis and High Performance of Hydraulic Servo Actuator

2020 ◽  
Vol 10 (21) ◽  
pp. 7451
Author(s):  
Yong-bum Lee ◽  
Jong-won Park ◽  
Gi-chun Lee
Keyword(s):  
Fatigue Life ◽  
Accelerated Life Testing ◽  
Test Equipment ◽  
Life Testing ◽  
Life Test ◽  
Accelerated Life ◽  
Servo Actuator ◽  
Hydraulic Servo ◽  
Automotive Parts ◽  
Fatigue Life Test

Hydraulic servo actuator is used as the core actuator in tensile compression fatigue life test equipment as it operates the micro displacement very precisely at a high frequency and can be used continuously for a long period of time. Recently, the life expectancy of automobiles has been extended, the load conditions of accelerated life testing on auto parts have been increased, and the life test time and number of tests have increased significantly in order to secure the reliability of the guaranteed life of produced vehicles. Therefore, hydraulic servo actuators mounted on accelerated life testing equipment for automotive parts are essential for much higher performance and a longer life than those tested. However, small- and medium-sized companies that supply test equipment for the fatigue life of auto often fail to develop technology due to a lack of research personnel and the development budget compared to the capabilities of large automobile manufacturers, resulting in frequent breakdowns due to the technical overload of test equipment. In this study, servo actuators were used to test automotive parts, with a maximum output of 2 ton, a maximum frequency of 3.3 Hz and a maximum displacement of 50 mm. The hydraulic servo actuator, which was installed in the tensile compression fatigue life test equipment, failed to operate normally at the site, and by analyzing it, we realized this resulted from the heat generation of insulation compression due to the accumulation of air and gas into the hydraulic oil and the increase in friction due to the deterioration of flow. A static pressure bearing was adopted as a design change to improve the root cause for this failure mode, and a very high level of geometric concentricity was secured by inserting concentric tubes outside the labyrinth seal type piston. The newly designed and manufactured actuator is the result of research that has achieved a semi-permanent long life and improved performance up to 100 Hz by non-contact operation.

Accelerated Life Testing Method of Transmission

2006 ◽  
Vol 326-328 ◽  
pp. 1865-1868
Author(s):  
Hyoung Eui Kim ◽  
Doh Sik Kim ◽  
Yoon Pyo Lee ◽  
Yung Chul Yoo
Keyword(s):  
Fatigue Damage ◽  
Service Use ◽  
Life Time ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Life Testing ◽  
Step Process ◽  
Testing Method ◽  
Accelerated Life ◽  
Cumulative Fatigue Damage

In this study, we proposed a process of an accelerated life testing method of 5-speed manual transmissions used in vehicles, which loads are consisted of multiple alternating loads. The entire process of an 5-speed manual transmission’s accelerated life testing method where no failures are allowed, is a process that requires an abundance of assumptions, and other factors that are estimates such as the shape parameter, beta() and the fatigue damage exponent (x). And the process is consisted of 7-step process. From the 1-setp, which is the deriving the service(use) torque and speed(rpm) profile of the transmission, to the 7-step, we could determine the accelerated life time, the accelerated torque and the accelerated speed(rpm), which are the equivalent cumulative fatigue damage. Also, we have performed accelerated life test on 5-speed manual transmission by using the following 7-step process.

Research on a New Model for Accelerated Life Test of Pneumatic Cylinders

2010 ◽  
Vol 40-41 ◽  
pp. 760-765 ◽  
Author(s):  
Chuan Dong Bai ◽  
Yan Wang ◽  
De Yi Wang
Keyword(s):  
Test Data ◽  
Accelerated Life Testing ◽  
Accelerated Life Test ◽  
Pneumatic Cylinder ◽  
Life Test ◽  
Working Pressure ◽  
Accelerated Life ◽  
Long Lifetime ◽  
Log Linear ◽  
Pneumatic Cylinders

Pneumatic cylinders, as a long lifetime product, are used continuously under normal conditions. So Accelerated Life Testing is an important tool to get information quickly on lifetime which is achieved by subjecting the test cylinders to conditions that are more severe than the normal ones. This paper firstly analyze the failure mechanism of pneumatic cylinder, then based on the General Log-Linear relationship and Weibull distribution, describes a model for multiple stress-type accelerated life data analysis. The paper gives the parameter statistical method of the mode by using likelihood theory. Based on the test data from ALT of pneumatic cylinders which adopt four test stresses including air temperature, motion frequency, working pressure and operation velocity, the parameter of the model are fitted. According to the test data and the estimated model, the paper extrapolates the pneumatic cylinder’s lifetime information under the normal user level.

Bearing life prognosis under environmental effects based on accelerated life testing

2002 ◽  
Vol 216 (5) ◽  
pp. 509-516 ◽  
Author(s):  
C Zhang ◽  
M T Le ◽  
B B Seth ◽  
S Y Liang
Keyword(s):  
Operating Conditions ◽  
Accelerated Life Testing ◽  
Model Verification ◽  
Accelerated Life Test ◽  
Experimental Result ◽  
Life Testing ◽  
Accelerated Life ◽  
Bearing Life ◽  
Stress Levels ◽  
Life Tests

The reliability of a bearing is typically estabilished by repeated life testing which provides valuable information on the fatigue mechanisms from crack initiation, crack propagation to flake or spall. Under nominal operating conditions, life testing often consumes a significant amount of time and resources, due to the comparatively high bearing mean lifetime before failure (MTBF), rendering the procedures expensive and impractical. Therefore, the technology of accelerated life testing (ALT), which is widely used in manufacturing practice, offers the attractive benefit of requiring relatively less investment in terms of time and resources. Data from tests at high stress levels (e.g. temperature, voltage, pressure, corrosive media, etc.) can be extrapolated, through a physically reasonable statistical model, to obtain life estimates at lower, normal stress levels. In this study, a methodology to predict bearing lifetime under a corrosive environment has been developed based on accelerated life testing data and the application of the inverse power law. Bearing life tests under various corrosion stress levels were performed for model identification followed by additional independent bearing life tests conducted for model verification. The experimental result shows that the accelerated life test model can effectively assess the life probability of a bearing based on accelerated environmental testing, even with extrapolation to untested stress levels.

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