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.

scholarly journals Reliability Design of Mechanical Systems Such as Compressor Subjected to Repetitive Stresses

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1261
Author(s):  
Seongwoo Woo ◽  
Dennis L. O’Neal
Keyword(s):  
Life Stress ◽  
Failure Modes ◽  
Action Plan ◽  
Valve Plate ◽  
Pressure Loading ◽  
Reliability Design ◽  
Mechanical Products ◽  
Reed Valve ◽  
Repetitive Impact ◽  
Design Defects

This study demonstrates the use of parametric accelerated life testing (ALT) as a way to recognize design defects in mechanical products in creating a reliable quantitative (RQ) specification. It covers: (1) a system BX lifetime that X% of a product population fails, created on the parametric ALT scheme, (2) fatigue and redesign, (3) adapted ALTs with design alternations, and (4) an evaluation of whether the system design(s) acquires the objective BX lifetime. A life-stress model and a sample size formulation, therefore, are suggested. A refrigerator compressor is used to demonstrate this method. Compressors subjected to repetitive impact loading were failing in the field. To analyze the pressure loading of the compressor and carry out parametric ALT, a mass/energy balance on the vapor-compression cycle was examined. At the first ALT, the compressor failed due to a cracked or fractured suction reed valve made of Sandvik 20C carbon steel (1 wt% C, 0.25 wt% Si, 0.45 wt% Mn). The failure modes of the suction reed valves were similar to those valves returned from the field. The fatigue failure of the suction reed valves came from an overlap between the suction reed valve and the valve plate in combination with the repeated pressure loading. 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 specified to perform the heat treatment to the exterior of the crankshaft made of cast iron (0.45 wt% C, 0.25 wt% Si, 0.8 wt% Mn, 0.03 wt% P). After these design modifications, there were no troubles during the third ALT. The lifetime of the compressor was secured to have a B1 life of 10 years.

scholarly journals Reliability Design of Mechanical Systems Such as Compressor Subjected to Repetitive Stresses

2021 ◽  
Vol 3 (1) ◽  
pp. 14
Author(s):  
Seongwoo Woo ◽  
Dennis L. O’Neal ◽  
Samson Mekbib Atnaw ◽  
Muluneh Mekonnen Tulu
Keyword(s):  
Fatigue Failure ◽  
Life Stress ◽  
Failure Modes ◽  
Action Plan ◽  
Mechanical Systems ◽  
Valve Plate ◽  
Pressure Loading ◽  
Reliability Design ◽  
Mechanical Products ◽  
Reed Valve

This paper suggests parametric accelerated life testing (ALT) as a systematic reliability technique to generate the reliability quantitative (RQ) specification such as mission cycle for identifying design flaws in mechanical systems as exerting the accelerated load, defined as the reverse of stress ratio, R. Parametric ALT therefore is a procedure to improve the fatigue for mechanical products subjected to repetitive loading. It includes: (1) a system BX lifetime shaped on the parametric ALT plan; (2) a fatigue failure and design; (3) tailored ALTs with alternatives; and (4) an assessment of whether the design(s) of the product attains the targeted BX lifetime. A BX life ideas, a life-stress model, and a sample size formulation for parametric ALT are proposed. A reciprocating compressor in a domestic refrigerator is utilized to explain this methodology. The compressor was subjected to repetitive impact loading due to the pressure difference between condenser and evaporator, which results in the compressor field failure. To analyze and conduct parametric ALTs, as mass/energy balance was utilized on the vapor-compression refrigerating cycle, a simple pressure loading of the compressor in operating the refrigerator was investigated. At the first ALT, the compressor was locked due to the fractured suction reed valve made of Sandvik 20C carbon steel (1 C, 0.25 Si, 0.45 Mn). The dominant failure modes of the suction reed valve in the parametric ALTs were established to be very close to that of the fractured product from the marketplace. The root cause of the fatigue failure of the suction reed valve was an amount of overlap between the suction reed valve and the valve plate in combination of repeated pressure loading in the compressor. To supply sufficient mechanical strength, the design faults were altered by the trespan dimensions tumbling process, a ball peening and brushing process for the valve plate. At the second ALT, a compressor was locked due to the intrusion between the crankshaft and the thrust washer. The corrective action plan was to give heat treat the surface of crankshaft made of cast iron (0.45 C, 0.25 Si, 0.8 Mn, 0.03 P). After these alternations, there were no issues at the third ALT. The lifetime of the compressor was ensured to have 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.

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%.

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