Solder Creep-Fatigue Interactions With Flexible Leaded Parts

1992 ◽  
Vol 114 (2) ◽  
pp. 185-192 ◽  
Author(s):  
R. G. Ross ◽  
L. C. Wen ◽  
G. R. Mon ◽  
E. Jetter
Keyword(s):  
Computer Program ◽  
Strain Rate ◽  
Thermal Cycle ◽  
Failure Process ◽  
Strain Range ◽  
Strain Rate Effects ◽  
Rate Effects ◽  
Creep Fatigue ◽  
Solder Fatigue

With flexible leaded parts, the solder-joint failure process involves a complex interplay of creep and fatigue mechanisms. To better understand the role of creep in typical multi-hour cyclic loading conditions, a specialized non-linear finite-element creep simulation computer program has been formulated. The numerical algorithm includes the complete part-lead-solder-PWB system, accounting for strain-rate dependence of creep on applied stress and temperature, and the role of the part-lead dimensions and flexibility that determine the total creep deflection (solder strain range) during stress relaxation. The computer program has been used to explore the effects of various solder creep-fatigue parameters such as lead height and stiffness, thermal-cycle test profile, and part/board differential thermal expansion properties. One of the most interesting findings is the strong presence of unidirectional creep-ratcheting that occurs during thermal cycling due to temperature dominated strain-rate effects. To corroborate the solder fatigue model predictions, a number of carefully controlled thermal-cycle tests have been conducted using special bimetallic test boards.

Temperature and Strain Rate Effects on Mechanical Behavior of a PMMA

2007 ◽  
Vol 340-341 ◽  
pp. 1079-1084 ◽  
Author(s):  
Tao Suo ◽  
Yu Long Li ◽  
Yuan Yong Liu
Keyword(s):  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Strain ◽  
Strain Range ◽  
Testing Temperature ◽  
Strain Rate Effects ◽  
Rate Effects ◽  
Increasing Temperature

In this paper, the mechanical behavior of a PMMA used as the windshield of aircraft was tested. The experiments were finished under two quasi-static strain rates and a high strain rate with the testing temperature from 299K to 373K. The results show that the mechanical property of this PMMA depends heavily on the testing temperature. The Young’s modulus and flow stress were found to decrease with increasing temperature at low strain rate. At the strain rate of 10-1 1/s, strain softening was observed under all experiment temperatures. At high strain rate, with the temperature increasing, the flow stress decreases remarkably while the failure strain increases, and the strain soften was also observed at the temperature above 333K. Comparing the experiments results at same temperature, it was found the flow stress increases with the rising strain rate. The predictions of the mechanical behavior using the ZWT theoretical model have a good agreement with experimental results in the strain range of 8%.

Strain Rate Effects on Mechanical Stability of Retained Austenite in TRIP Sheet Steels

2006 ◽  
Author(s):  
Ildong Choi ◽  
Dongmin Son ◽  
Sung-joon Kim ◽  
David K. Matlock ◽  
John G. Speer
Keyword(s):  
Strain Rate ◽  
Retained Austenite ◽  
Mechanical Stability ◽  
Strain Rate Effects ◽  
Sheet Steels ◽  
Rate Effects
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