scholarly journals Improving the Reliability of Mechanical Components That Have Failed in the Field Due to Repetitive Stress

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 38 ◽  
Author(s):  
Seongwoo Woo ◽  
Dennis L. O’Neal
Keyword(s):  
Failure Modes ◽  
Action Plan ◽  
Accelerated Life Testing ◽  
Test Case ◽  
Mechanical Parts ◽  
Accelerated Life ◽  
Repetitive Loading ◽  
Design Requirements ◽  
Load Analysis ◽  
Repetitive Stress

To improve the reliability of mechanical parts that have failed in the field, a reliability methodology for parametric accelerated life testing (ALT) is proposed. It consists of: (1) a parametric ALT plan, (2) a load analysis, (3) a tailored series of parametric ALTs with action plans, and (4) an evaluation of the final designs to ensure the design requirements are satisfied. This parametric ALT should help an engineer reproduce the fractured or failed parts in a product subjectedto repetitive loading and correct the faulty designs. As a test case, the helix upper dispenser of a refrigerator ice-maker fractured in field was studied. Using a load analysis, we discerned that the helix upper dispenser fracture was due to repetitive loads and a faulty design with a 2 mm gap between the blade dispenser and the helix upper dispenser. During the first and second ALTs, the fracture in the helix upper dispenser was reproduced. The failure modes and mechanisms found were similar to those of the failed sample in field. As an action plan, the design of the helix upper dispenser was modified by eliminating the 2 mm gap and adding enforced ribs. In the third ALT there were no problems. After three rounds of parametric ALTs, the reliability of the helix upper dispenser was guaranteed as a 10-year life with an accumulated failure rate of 1%.

Study on Reliability Design of the Domestic Compressor Subjected to Repetitive Internal Stresses by Parametric Accelerated Life Testing

2022 ◽  
pp. 241-266
Author(s):  
Seongwoo Woo ◽  
Dennis L. O'Neal ◽  
Yimer Mohammed Hassen
Keyword(s):  
Life Stress ◽  
Failure Modes ◽  
Action Plan ◽  
Accelerated Life Testing ◽  
Valve Plate ◽  
Life Testing ◽  
Accelerated Life ◽  
Mechanical Products ◽  
Reed Valve ◽  
Design Defects

This chapter explains the parametric accelerated life testing (ALT) to recognize design defects in mechanical products. A life-stress model and a sample size formulation are suggested. A compressor is used to demonstrate this method. Compressors were failing in the field. At the first ALT, the compressor failed due to a fractured suction reed valve. The failure modes were similar to those valves returned from the field. The fatigue of the suction reed valves came from an overlap between the suction reed valve and the valve plate. The problematic design was modified by the trespan dimensions, tumbling process, a ball peening, and brushing process for the valve plate. At the second ALT, the compressor locked due to the intrusion between the crankshaft and thrust washer. The corrective action plan performed the heat treatment to the exterior of the crankshaft made of cast iron. After the design modifications, there were no troubles during the third ALT. The lifetime of compressor was secured to have a B1 life 10 years.

Reliability Test and Evaluation Analysis of Silicon Pressure Sensor under Vibration Stress

2011 ◽  
Vol 383-390 ◽  
pp. 6969-6974
Author(s):  
Li Qin ◽  
An Li Shi
Keyword(s):  
Pressure Sensor ◽  
Failure Modes ◽  
Accelerated Life Testing ◽  
Life Testing ◽  
Average Life ◽  
Test And Evaluation ◽  
Inverse Power Law ◽  
Accelerated Life ◽  
Testing Data ◽  
Vibration Stress

The model silicon pressure sensor was taken as the object; in this paper, we built failure physics equation of sensor under the vibration stress based on the failure modes and failure mechanism of pressure sensor, and using vibration stress as the acceleration factor to process accelerated life testing under invariableness stress. The results show that failure physics equation of sensor yields the inverse power law relationship. The estimated value of reliability character and accelerated life equation of sensor under the vibration stress was attained through analyzing testing data and the average life and reliable life of sensor has been attained through reliability evaluation.

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.

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