Vibration Durability Assessment of Sn3.0Ag0.5Cu and Sn37Pb Solders Under Harmonic Excitation

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Y. Zhou ◽  
M. Al-Bassyiouni ◽  
A. Dasgupta
Keyword(s):  
Mechanical Engineering ◽  
Failure Modes ◽  
Narrow Band ◽  
Low Cycle Fatigue ◽  
Stress Test ◽  
Harmonic Excitation ◽  
Cycle Fatigue ◽  
Mechanical Cycling ◽  
Mechanical Durability ◽  
Vibration Tests

In this paper, the vibration durability of both SAC305 and Sn37Pb interconnects are investigated with narrow-band harmonic vibration tests conducted at the first natural frequency of the test, printed wiring board, using constant-amplitude excitation. A time-domain approach, reported by Upadhyayula and Dasgupta (1998, “Guidelines for Physics-of-Failure Based Accelerated Stress Test,” Proceedings, Reliability and Maintainability Symposium, pp. 345–357), was adapted in this study for the fatigue analysis. The test board consists of daisy-chained components, to facilitate real-time failure monitoring. The response of the test specimens was characterized, and accelerated fatigue tests were conducted at different loading amplitudes to obtain a mix of low-cycle fatigue (LCF) and high-cycle fatigue data points. The SAC305 interconnects were found to have lower fatigue durability than comparable Sn37Pb interconnects, under the narrow-band harmonic excitation levels used in this study. This trend is consistent with most results from broadband vibration tests by Zhou et al. (2006, “Vibration Durability Comparison of Sn37Pb vs. SnAgCu Solders,” Proceedings of ASME International Mechanical Engineering Congress and Exposition, Chicago, IL, Paper No. 13555), Zhou and Dasgupta (2006, “Vibration Durability Investigation for SnPb and SnAgCu Solders With Accelerated Testing and Modeling,” IEEE-TC7 Conference on Accelerated Stress Testing & Reliability, San Francisco, CA), and Woodrow (2005, “JCAA/JG-PP No-Lead Solder Project: Vibration Test,” Boeing Electronics Materials and Processes Technical Report) and from repetitive mechanical shock tests by Zhang et al. (2005, “Isothermal Mechanical Durability of Three Selected Pb-Free Solders: Sn3.9Ag0.6Cu, Sn3.5Ag and Sn0.7Cu,” ASME J. Electron. Packag., 127, pp. 512–522), but counter to findings from quasistatic, LCF, and mechanical cycling studies by Cuddalorepatta and Dasgupta (2005, “Cyclic Mechanical Durability of Sn3.0Ag0.5Cu Pb-Free Solder Alloy,” Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Orlando, FL, Paper No. 81171). Failure analysis revealed two competing failure modes, one in the solder and another in the copper trace under the component. Thus solder fatigue properties extracted with the help of finite element simulation of the test article should be treated as lower-bound estimates of the actual fatigue curves.

Damage in Adhesive Joints During Low Cycle Fatigue

2010 ◽  
Author(s):  
Iva´n C. Ca´bulo-Pe´rez ◽  
Juan P. Casas-Rodri´guez
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Stress Test ◽  
Damage Model ◽  
Fatigue Tests ◽  
Constant Stress ◽  
Cycle Fatigue ◽  
Damage Behavior ◽  
Non Linear ◽  
Compressive Loads

The objective of this research is to study the damage behavior of bulk adhesive and single lap joint (SLJ) specimens during low cycle fatigue (LCF). Fatigue tests under constant stress amplitude were done and strain response was measured through cycles to failure using the bulk adhesive and SLJ data. A non linear damage model was used to fit experimental results. Identification of the damage parameters for bulk adhesive was obtained from the damage against accumulated plastic strain plot. It is shown that the plastic strain can be obtained from the constant stress test if the instantaneous elastic modulus, i.e. modulus affected by damage, is evaluated for each cycle. On the other hand, damage in SLJ was seen mainly in the adhesive for itself — no substrate failure — this fact is used to propose that fatigue response in the joint is due to continuum damage accumulation in the adhesive as the number of cycles increases. Damage behavior under compressive loads was not taken into account but good correlation of numerical and experimental data was obtained. It was found that damage evolution behaves in a non linear manner as the plastic deformation grows for each cycle: on fatigue onset an accelerated damage grow is observed, then a proportional evolution, and finally a rapid failure occurs; this characteristics were seen in both the SLJ and bulk adhesive specimen. So far, this research takes the damage model found in a standard adhesive specimen and assumes it is accurate enough to represent the damage behavior of the SLJ configuration.

Failure Analysis of Thinned Wall Elbows Under Excessive Seismic Loading

2002 ◽  
Author(s):  
Masaki Shiratori ◽  
Yoji Ochi ◽  
Izumi Nakamura ◽  
Akihito Otani
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Local Buckling ◽  
Seismic Loading ◽  
Cycle Fatigue ◽  
Finite Element Analyses ◽  
Residual Thickness ◽  
Limited Period

A series of finite element analyses has been carried out in order to investigate the failure behaviors of degraded bent pipes with local thinning against seismic loading. The sensitivity of such parameters as the residual thickness, locations and width of the local thinning to the failure modes such as ovaling and local buckling and to the low cycle fatigue damage has been studied. It has been found that this approach is useful to make a reasonable experimental plan, which has to be carried out under the condition of limited cost and limited period.

Piping Stress-Strain Correlation for Seismic Loading

1988 ◽  
Vol 110 (4) ◽  
pp. 444-450
Author(s):  
G. Stawniczy ◽  
W. R. Bak ◽  
G. Hau
Keyword(s):  
Pressure Vessel ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Seismic Loading ◽  
Evaluation Procedure ◽  
Test Results ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Safety Margins ◽  
Fatigue Evaluation

This paper establishes limits on piping material strains for ASME Boiler and Pressure Vessel Code Level D loadings that ensure a limitation of deformation and provide suitable safety margins. In establishing the strain limits, potential piping failure modes due to compressive wrinkling and low-cycle fatigue are considered. A stress-strain correlation methodology to convert linear, elastically calculated Code Class 2 and 3 equation (9)-Level D stresses to strains is established. This correlation is based on the fatigue evaluation procedure of the Code and is verified by comparison with test results. A detailed discussion of test results compared with the stress-strain correlation methodology is also presented.

Effect of Reinforcement on the Strength of Junctions Between Cylindrical and Conical Shells

1995 ◽  
Vol 117 (2) ◽  
pp. 135-141 ◽  
Author(s):  
A. Kalnins ◽  
D. P. Updike
Keyword(s):  
Failure Criterion ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Safety Margin ◽  
External Pressure ◽  
Cycle Fatigue ◽  
Conical Shells ◽  
Section Viii ◽  
Cyclic Service ◽  
Reinforcement Distribution

Two failure modes are addressed for cylinder-cone junctions under internal or external pressure: axisymmetric yielding and low-cycle fatigue. If the junction fails to meet the failure criterion of any one of the two modes, then it must be strengthened by reinforcement. It is shown in the paper that the degree to which a junction is strengthened depends on the distribution of the reinforcement. A placement of reinforcement on the cylinder alone, leaving the actual connection between the cylinder and cone unreinforced, adds strength with regard to axisymmetric yielding, but may not strengthen the junction sufficiently with regard to low-cycle fatigue. This means that the junction may appear reinforced, but is not strengthened. It is pointed out that the design rules of Section VIII, Div. 1 of the ASME B & PV Code (1992) set the need for reinforcement according to the failure criterion of low-cycle fatigue, while the distribution of the reinforcement is guided by the criterion of axisymmetric yielding. There is no assurance that the reinforced junction will meet the failure criterion of low-cycle fatigue. This means that the safety margin on the number of allowed cycles is less than that which is expected and that the junction may be unfit for cyclic service. It is also shown in the paper that a reinforcement distribution that requires minimum thicknesses for sections of both the cylinder and cone near the junction can satisfy criteria for both failure modes. This approach is already used in Code Case 2150 of Section VIII, Div. 1, for half-apex cone angles from 30 to 60 deg, and required in Div. 2 for cone angles from 0 to 30 deg. Its extension to angles from 0 to 60 deg for both internal and external pressure is recommended.

Experimental investigation into ultra-low cycle fatigue behavior of composite members in spatial grid structures

2020 ◽  
Vol 23 (12) ◽  
pp. 2514-2528
Author(s):  
Xiayun Song ◽  
Haiwang Li ◽  
Jie Zhang
Keyword(s):  
Energy Dissipation ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Plastic Hinge ◽  
Cumulative Damage ◽  
Cycle Fatigue ◽  
Plastic Hinges ◽  
Energy Dissipation Capacity ◽  
Spatial Grid

As earthquakes tend to cause ultra-low cycle fatigue failure of spatial grid structures in composite members and joints, this study sets out to test six groups of specimen comprising steel pipes and bolt sphere joints and analyzes the influence of joints and loading systems on failure modes, hysteretic behavior, skeleton curves, stiffness degradation, energy dissipation capacity, and the formation and development of plastic hinges. Results showed that the instability of the specimen in compressive loading led to the occurrence of denting and the formation of plastic hinges. Cracks originated in dented area, and ultra-low cycle fatigue fractures occurred in a dozen cycles. Plastic hinge was located in the middle area of the pipe, and the energy dissipation capacity was limited owing to the confined plastic hinge length. As the joint bending stiffness increased, so did the length of the plastic hinge, the degree of the dent, and the cumulative damage. Early fractures and a reduction in total energy consumption also occurred. Furthermore, a function related to the cumulative damage and macroscopic deformation that can evaluate the damage of the members in spatial grid structures was also established.

Cumulative Seismic Damage of Reinforced Concrete Columns: Benchmark and Low-Cycle Fatigue Tests

2011 ◽  
Vol 52-54 ◽  
pp. 734-739 ◽  
Author(s):  
Yuan Pan ◽  
Guo Hua Xing ◽  
Guo Fu ◽  
Jian Ling Hou
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Low Cycle Fatigue ◽  
High Stress ◽  
Concrete Columns ◽  
Companion Paper ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Cycle Fatigue ◽  
Reinforced Concrete Columns

Under seismic actions, reinforced concrete columns are generally damaged by a combination of repeated stress reversals and high stress excursions. An experimental study was undertaken to investigate cumulative damage in reinforced concrete rectangular columns subjected to repeated cyclic loadings. Fourteen identical half-scale concrete columns were fabricated and tested to failure. This paper summarizes the results of Phase I testing that consisted of benchmark tests to establish the monotonic force-deformation envelope, and constant amplitude tests to determine the low-cycle fatigue characteristics of typical flexural columns. A companion paper will present the results of variable amplitude tests to develop an analytical model of cumulative damage for rectangular reinforced concrete columns. Test observations indicate two potential failure modes: low cycle fatigue of the longitudinal reinforcing bars; and confinement failure due to rupture of the confining hoops. The former failure mode is associated with relatively large displacement amplitudes, while the latter is associated with a larger number of smaller amplitude cycles. A fatigue life expression is developed that can be used in damage-based seismic design of rectangular, flexural concrete columns.

Vibration Durability Assessment of Sn3.0Ag0.5Cu and Sn37Pb Solders Under Harmonic Excitation

2007 ◽  
Author(s):  
Yuxun Zhou ◽  
Abhijit Dasgupta
Keyword(s):  
Finite Element ◽  
Narrow Band ◽  
Broad Band ◽  
Harmonic Excitation ◽  
Cycle Fatigue ◽  
Durability Test ◽  
Strain Transfer ◽  
Test Board ◽  
Snpb Solder ◽  
Eutectic Snpb

In this paper, the vibration durability of both SAC305 & eutectic SnPb interconnects is investigated with narrow-band harmonic vibration tests and finite element simulation. The tests are conducted at the first natural frequency of the test board using constant amplitude excitation. Compared to broad-band vibration durability test, the advantage of harmonic test is less complexity, hence, less uncertainty in the desired fatigue constant. A time-domain approach, reported in the literature 0, was adapted in this study for the fatigue analysis. The test board consists of daisy-chained components, to facilitate real-time failure monitoring. The tests are conducted at different loading amplitude to obtain the durability data points located at both low cycle fatigue and high cycle fatigue region. The SAC305 solder was found to have lower fatigue durability than the SnPb solder, under narrow-band harmonic excitation, which is consistent with results from broad-band vibration test 0, as well as with results of mechanical cycling studies and repetitive mechanical shock studies conducted earlier 0. The test board was first characterized before the vibration durability test. A modal test was conducted to determine the mode shape and natural frequency, which were used to decide the excitation frequency of durability test. Flexure strain amplitudes at critical locations on the PWB were first characterized with strain gages at each level used in the test excitation. Detailed local finite element analysis was then conducted to estimate the strain transfer function between the PWB flexure strain and the strain in the critical solder joints for selected components (BGA256, LCR1210 and LCR2512). Then the strain history in the critical solder joint was estimated from the measured PWB strain, using the strain transfer function. Finally the solder strain and the measured time-to-failure data were used to estimate durability model constants for a generalized strain-life fatigue model 0 for both SAC305 and eutectic SnPb solder. Destructive failure analysis (cross-sectioning, polishing and microscopy) was used to confirm that the failure was by solder fatigue.

Low Cycle Fatigue of Structural Alloys

2021 ◽  
Vol 1038 ◽  
pp. 3-8
Author(s):  
Ivan Medved ◽  
Oleksandr Pirogov ◽  
Andrey Romin ◽  
Vitalii Slovinskyi ◽  
Galyna Venzhego
Keyword(s):  
Cyclic Loading ◽  
Elastoplastic Deformation ◽  
Mechanical Engineering ◽  
Low Cycle Fatigue ◽  
Shell Structures ◽  
Cryogenic Temperatures ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Material Consumption ◽  
Cryogenic Engineering

Metallurgy, mechanical engineering, energy, agriculture, food industry, energy, electronics, rocket and space technology – this is a far from complete list of areas of the national economy in which liquid cryogenic products (cryoproducts). The production volumes of such products and the scale of their use are constantly increasing. This is due to the fact that cryogenic temperatures (below 120 K) provide unique opportunities for the implementation of such physical phenomena and processes that do not manifest themselves under normal conditions, but are used very effectively in science and technology. The solution of fundamental scientific problems and applied problems of both promising and current importance is determined by the level of development of cryogenic technology and the degree of its practical application. The continuous expansion of the scale of production of liquid cryogenic products has led in recent years to a significant increase in the volume of production of systems for their storage and transportation. These systems, as a rule, are welded shell structures in execution, they are operated in difficult conditions of temperature and force effects. The share of their production in the total output of cryogenic engineering products is very significant, and the operating conditions are the most stressful in comparison with other types of cryogenic structures. For the manufacture of cryogenic shell structures, expensive non-ferrous alloys and special steels are used, the degree of consumption of which, taking into account the sufficient material consumption of such structures and the expanding scale of their production, is constantly increasing. Therefore, one of the most urgent for cryogenic mechanical engineering at present is the problem of reducing the material consumption of shell structures and increasing their reliability and durability. It is obvious that a solution to this problem for cryogenic engineering products can be achieved by improving the methods of their strength calculations based on taking into account the specific hardening effect of low temperature on structural alloys. The phenomenon of low-cycle fatigue of metals is associated with elastoplastic deformation of their macrovolumes. The kinetics of elastoplastic deformation processes under cyclic loading depends on the loading conditions and material properties, and the nature of these processes and their intensity have a decisive influence on the features of material destruction. If the accumulation of deformation is small, then the destruction, as a rule, is of a fatigue nature; quasi-static fracture (similar in appearance to fracture during static tests for short-term strength) occurs after the realization of the ultimate plasticity of the material. The task of assessing the bearing capacity and durability under cyclic loading conditions is extremely important. Under cyclic loading, a number of specific phenomena and factors that are difficult to take into account analytically arise, which are primarily associated with the development of fatigue damage, with the need to assess the cyclic and structural instability of materials [1]. Since such studies are very laborious and expensive, the problem of minimizing such experiments is currently urgent. In this paper, we investigate the possibility of using mathematical planning methods for experimental studies at cryogenic temperatures. Experiment planning is usually understood as the procedure for choosing the volume and conditions of testing necessary and sufficient to solve the problem with the required accuracy.

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