Aging effects on shear fatigue life and shear strength of soldered thick film joints

1998 ◽  
Vol 21 (4) ◽  
pp. 398-406 ◽  
Author(s):  
G. Y. Li ◽  
Y. C. Chan
Keyword(s):  
Shear Strength ◽  
Fatigue Life ◽  
Thick Film ◽  
Aging Effects ◽  
Shear Fatigue

scholarly journals Effect of Repetitive Collar Replacement on the Residual Strength and Fatigue Life of Retained Hi-Lok Fastener Pins

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 445 ◽  
Author(s):  
David F. Hardy ◽  
David L. DuQuesnay
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Fatigue Life ◽  
Failure Mode ◽  
Residual Strength ◽  
Clamping Force ◽  
Ultimate Shear Strength ◽  
Shear Fatigue ◽  
Static Tensile ◽  
Static Shear

Hi-Lok fasteners were subjected to multiple collar replacements, and were tested under static loading and constant-amplitude fatigue loading, to determine the effect of repetitive collar replacement on the residual strength and fatigue life of a retained Hi-Lok-type fastener pin. Hi-Lok-type fasteners are typically used in aircraft structural joints, and are loaded mainly in shear. Tests were conducted for clamping force, static shear strength, static tensile strength, and shear fatigue life for collars subjected to five collar replacements. The static shear results showed no decrease in the ultimate shear strength of the fastener pin as a function of collar replacement. Static tensile results showed no decrease in the ultimate tensile strength of the fastener as a function of collar replacement, with failure of the aluminum collar remaining the critical failure mode. Similarly, shear fatigue results showed no decrease in the shear fatigue life of the fastened joint as a result of collar replacement, with fracture of the aluminum substrate remaining the critical failure mode. For static shear, static tension, and shear fatigue tests, estimated clamping force was highly consistent between specimens and no decrease in clamping force was observed as a function of collar replacement.

Effect of CO2 Saturation and Desorption on the Fatigue Life of Polycarbonate

1994 ◽  
Vol 116 (4) ◽  
pp. 451-456 ◽  
Author(s):  
K. A. Seeler ◽  
Vipin Kumar
Keyword(s):  
Shear Strength ◽  
Fatigue Life ◽  
Yield Strength ◽  
Fatigue Cracks ◽  
Saturation Pressure ◽  
Stress Relief ◽  
Shear Fatigue ◽  
Static Yield ◽  
Swelling Strain ◽  
Slow Growing

The effect of a cycle of CO2 saturation and desorption on the yield strength, Young’s modulus, and fatigue life of polycarbonate was investigated. The fatigue life of the saturation-cycled polycarbonate exceeded that of unprocessed polycarbonate by up to a factor of thirty. The fatigue life of these rough-surfaced saturation-cycled specimens was approximately equal to or greater than that of polished smooth bar specimens. The increase in fatigue life is a function of the CO2 saturation pressure, reaching a maximum at the same saturation pressure at which there is no further reduction in static yield strength. The increased fatigue life is hypothesized to result from one or more of following mechanisms: (1) reduction of shear strength promoting slow-growing shear fatigue cracks: (2) “healing” or blunting of pre-existing flaws or microcracks by swelling strain or by stress relief strain resulting from plasticization by CO2 during saturation.

scholarly journals Shear Fatigue Performance of Epoxy Resin Waterproof Adhesive Layer on Steel Bridge Deck Pavement

2021 ◽  
Vol 7 ◽  
Author(s):  
Ying Xu ◽  
Xinpeng Lv ◽  
Chunfeng Ma ◽  
Fengming Liang ◽  
Jiafei Qi ◽  
...  
Keyword(s):  
Shear Strength ◽  
Fatigue Life ◽  
Epoxy Resin ◽  
Bridge Deck ◽  
Adhesive Layer ◽  
Fatigue Performance ◽  
Steel Bridge ◽  
Shear Fatigue ◽  
Interlaminar Shear ◽  
Bridge Deck Pavement

In this study, the effects of temperature, shear stress, and coating quantity of waterproof adhesive layer on the shear fatigue performance of a steel bridge deck pavement were investigated. Direct shear fatigue tests of a pavement comprising an epoxy resin waterproof adhesive layer with stone matrix asphalt were conducted at different temperatures, stress levels, and coating quantities. The results show that temperature and stress have significant effects on the shear fatigue life. With increasing temperature and stress, the shear fatigue life of the waterproof adhesive layer decreased gradually. Therefore, for steel bridge deck pavements under high temperatures and heavy loads, the use of asphalt waterproof adhesive layers or pavement layers should be evaluated carefully while limiting the traffic of heavily loaded vehicles. Shear failure occurs at the waterproof adhesive layer–pavement interface and not at the steel–waterproof adhesive layer interface. The shear strength of the epoxy resin waterproof adhesive layer is mainly provided by the bond strength between the waterproof adhesive and pavement mixture as well as the interlocking force between the cured epoxy resin and the bottom interface of uneven pavement mixture. The shear strength increases with the coating quantity of the waterproof adhesive layer; however, after reaching the maximum value, the shear strength becomes stable. In contrast, the interlaminar shear fatigue life increases continuously with the coating quantity of the waterproof adhesive layer. Appropriately increasing the coating quantity is beneficial for improving the resistance of the waterproof adhesive layer to interlaminar shear fatigue failure.

Evaluation of Representative Piping Systems Designed by Implicit Fatigue Concept

2008 ◽  
Author(s):  
Shin-Beom Choi ◽  
Sun-Hye Kim ◽  
Yoon-Suk Chang ◽  
Jae-Boong Choi ◽  
Young-Jin Kim ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Nuclear Power ◽  
Heat Removal ◽  
Environmental Water ◽  
Lessons Learned ◽  
Metal Fatigue ◽  
Aging Effects ◽  
Age Related ◽  
Piping Systems ◽  
Surge Line

NUREG-1801 provides generic aging lessons learned to manage aging effects that may occur during continued operation beyond the design life of nuclear power plant. According to this report, the metal fatigue, among several age-related degradation mechanisms, is identified as one of time-limited aging analysis item. The objective of this paper is to introduce fatigue life evaluation of representative surge line and residual heat removal system piping which was designed by implicit fatigue concept. For the back-fitting evaluation employing explicit fatigue concept, detailed parametric CFD as well as FE analyses results are used. The well-known ASME Section III NB-3600 procedure is adopted for the metal fatigue and NUREG/CR-5704 procedure is further investigated to deal with additional environmental water effects. With regard to the environmental effect evaluation, two types of fatigue life correction factors are considered, such as maximum Fen and individual Fen. As a result, it was proven that a thermal stratification phenomenon is the governing factor in metal fatigue life of the surge line and strain rate is the most important parameter affecting the environmental fatigue life of both piping. The evaluation results will be used as technical bases for continued operation of OPR 1000 plant.

Mobile Packaging and Interconnect Trends

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 1-21
Author(s):  
Brandon Prior
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Thick Film ◽  
Cross Sections ◽  
Shear Test ◽  
Short Review ◽  
Test Machine ◽  
Die Attach ◽  
Shear Failures ◽  
Film Substrate

This paper will focus on emerging and fast growth package solutions to meet mobile products' density and cost requirements. A short review of where package miniaturization and modularization has taken us so far, and where it will lead in the next 5 years. Teardowns of high density systems and packages will be used to illustrate key points. Low temperature Ag sintering technology provides a lead-free die attachment compatible with high temperature (300°C) applications. Previous work with Ag sintering has required some pressure during the sintering process or been limited to small area die. In this paper, a pressureless sintering of micro-scale silver paste procedure is presented for large (8mm x 8mm) area die. Experimental combinations included: Ag metallized Si die, Au metallized Si die, Ag thick film substrate metallization, Au thick film substrate metallization, PdAg thick film metallization and sintering temperature. For Au metallization (die and/or substrate), the initial shear strength results were good with 8mm x 8mm die sintered at lower temperatures (200°C). The shear strength was out range of our shear test machine (100 kg), corresponding to >15.3 MPa. However, after aging for 24 hours at 300°C, the shear strength dropped significantly to 40.38 Kg (6.183 MPa). An SEM was used to characterize cross sections of as-built and aged sample. The decrease in die shear strength with high temperature sintering (250°C and 300°C) or high temperature aging is attributed to surface diffusion of Ag along the Au surface resulting in a dense Ag layer adjacent to the Au surface and a depletion layer within the die attach on the opposite side of the the dense Ag layer. Shear failures occurred through the depleted region. For Ag metallization, no decrease in shear strength was observed with 300°C aging. Shear strength of 8x8cm2 dies was out range of our shear test machine (>100 kg, >15.3 MPa) as-built. The shear strength remained out of range (>15.3MPa) after more than 2000 hours of 300C aging.

Development of low temperature sintered nano silver pastes using MO technology and resin reinforcing technology

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000172-000177
Author(s):  
Koji Sasaki ◽  
Noritsuka Mizumura
Keyword(s):  
Shear Strength ◽  
Low Temperature ◽  
Thermal Cycling ◽  
Thick Film ◽  
Thermal Performance ◽  
Low Temperature Sintering ◽  
Thermal Cycling Test ◽  
Nano Silver ◽  
Cycling Test ◽  
Thick Film Technology

Traditional thick film technology is widely used in various electronics products. There are two type of paste based on thick film technology. Typically, over 400°C is required for high temperature sintering type which contains glass for adhesion function. It shows high electrical and thermal performance. On the other hand, 150–300°C range process is used for low temperature process type as silver epoxy. In last decade, nano silver technology shows amazing progress to address low temperature operation by low temperature sintering. This paper will discuss the results on fundamental study of newly developed nano silver pastes with unique approach which uses MO (Metallo-organic) technology and resin reinforcing technology. Nano silver pastes contain several types of dispersant as surface coating to prevent agglomeration of the particles. Various coating technique has been reported to optimize sintering performance and stability. MO technology provides low temperature sintering capability by minimizing the coating material. The nano silver pastes show high electrical and thermal performance. However, degradation of die shear strength has been found by thermal cycling test due to the fragility of porous sintered structure. To improve the mechanical property, resin reinforcing technology has been developed. By adding special resin to the pastes, the porous area is filled with the resin and the sintered structure is reinforced. Degradation of die shear strength was not found by thermal cycling test to 1000 cycles. Nano silver pastes using MO technology and resin reinforcing technology will meet lots of requirement on various thick film applications.

Correlation of shear strength, fatigue limit and fatigue life of six high impact denture resins

2011 ◽  
Vol 27 ◽  
pp. e64-e65
Author(s):  
L.H. Mair ◽  
A. Langfield ◽  
R.L. Walton ◽  
Y.F. Mansour
Keyword(s):  
Shear Strength ◽  
Fatigue Life ◽  
Fatigue Limit ◽  
High Impact
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