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.

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.

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.

ACCELERATED LIFE TESTING OF COMPONENTS OF NUCLEAR RESEARCH REACTORS

2016 ◽  
Author(s):  
Vanderley Vasconcelos ◽  
WELLINGTON SOARES ◽  
Antonio Carlos Lopes da Costa ◽  
Raíssa Oliveira Marques
Keyword(s):  
Nuclear Research ◽  
Accelerated Life Testing ◽  
Life Testing ◽  
Research Reactors ◽  
Accelerated Life
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