Damage Mechanics Model for Solder/Intermetallics Interface Fracture Process in Solder Joints

2011 ◽  
Vol 462-463 ◽  
pp. 1409-1414
Author(s):  
N.M. Shaffiar ◽  
Z.B. Lai ◽  
Mohd Nasir Tamin
Keyword(s):  
Crack Initiation ◽  
Fracture Process ◽  
Damage Mechanics ◽  
Solder Ball ◽  
Solder Joints ◽  
High Stress ◽  
Interface Fracture ◽  
Dynamic Crack ◽  
Fe Model ◽  
Ball Shear

The relatively brittle solder/IMC interface fracture process in reflowed solder joints is examined using finite element (FE) method. The interface decohesion is described using a traction-separation quadratic failure criterion along with a mixed-mode displacement formulation for the interface fracture event. Reflowed Sn-4Ag-0.5Cu (SAC405) solder ball on OSP copper pad and orthotropic FR4 substrate under ball shear push test condition at 3000 mm/sec is simulated. Unified inelastic strain constitutive model describes the strain rate-response of the SAC405 solder. Comparable simulated and measured load-displacement values during solder ball shear push test serve as validation of the damage-based FE model. Results indicate a nonlinear damage evolution at each material point of the solder/IMC interface during the ball shear push test. The normal-to-shear traction ratio at the onset of the interface fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid interface crack propagation is predicted following crack initiation event with the average crack speed up to 24.6 times the applied shear tool speed. The high stress concentration along the edge of the solder/IMC interface facilitates local crack initiation and dictates the shape of the predicted dynamic crack front.

Gaussian Process Based Crack Initiation Modeling for Design of Battery Anode Materials

2019 ◽  
Author(s):  
Zhuoyuan Zheng ◽  
Yanwen Xu ◽  
Bo Chen ◽  
Pingfeng Wang
Keyword(s):  
Crack Initiation ◽  
Surrogate Model ◽  
High Stress ◽  
Lithium Ion ◽  
Electrochemical Process ◽  
Fe Model ◽  
Model Framework ◽  
Major Drawback ◽  
Cracking Behavior ◽  
Si Anode

Abstract Silicon-based anode is one of the promising candidates for the next generation lithium ion batteries (LIBs) to achieve high power/energy density. However, the major drawback limiting the practical application of Si anode is that Si experiences significant volume change during its lithiation/de-lithiation cycles, which induces high stress and causes degradation and pulverization of the anode. This study focuses on the crack initiation performances of Si anode during the de-lithiation process. A multi-physics based finite element (FE) model is built to simulate the electrochemical process and crack generation during de-lithiation. On top of that, a Gaussian Processes (GP) based surrogate model is developed to assist the exploration of the crack initiation performances within the anode design space. It is found that, the thickness of the Si coating layer TSi, the yield strength σFc of Si material, the cohesive strength between Si and substrate σFs, and the curvature of the substrate ρ have large impacts on the cracking behavior of Si. This coupled FE simulation-GP surrogate model framework is also applicable to other types of LIB electrodes.

The Effect of Ball Pad Metallurgy and Ball Composition on Solder Ball Integrity of Plastic Ball Grid Array Packages

1998 ◽  
Author(s):  
C.H. Zhong ◽  
Sung Yi
Keyword(s):  
Failure Mode ◽  
Barrier Layer ◽  
Shear Force ◽  
Solder Ball ◽  
Ball Grid Array ◽  
Reliability Test ◽  
Shear Forces ◽  
Ball Shear ◽  
Plastic Ball ◽  
Plastic Ball Grid Array

Abstract Ball shear forces of plastic ball grid array (PBGA) packages are found to decrease after reliability test. Packages with different ball pad metallurgy form different intermetallic compounds (IMC) thus ball shear forces and failure modes are different. The characteristic and dynamic process of IMC formed are decided by ball pad metallurgy which includes Ni barrier layer and Au layer thickness. Solder ball composition also affects IMC formation dynamic process. There is basically no difference in ball shear force and failure mode for packages with different under ball pad metallurgy before reliability test. However shear force decreased and failure mode changed after reliability test, especially when packages exposed to high temperature. Major difference in ball shear force and failure mode was found for ball pad metallurgy of Ni barrier layer including Ni-P, pure Ni and Ni-Co. Solder ball composition was found to affect the IMC formation rate.

scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

Dynamic crack initiation and growth in cellulose nanopaper

Cellulose ◽  
2021 ◽  
Author(s):  
Chengyun Miao ◽  
Haishun Du ◽  
Xinyu Zhang ◽  
Hareesh V. Tippur
Keyword(s):  
Crack Initiation ◽  
Dynamic Crack ◽  
Cellulose Nanopaper

A dynamic source model for the San Fernando earthquake

1978 ◽  
Vol 68 (6) ◽  
pp. 1555-1576
Author(s):  
Michel Bouchon
Keyword(s):  
Fault Plane ◽  
High Stress ◽  
Time History ◽  
High Strength ◽  
High Amplitude ◽  
Tectonic Stress ◽  
Source Model ◽  
Dynamic Crack ◽  
San Fernando ◽  
High Level

abstract We model the San Fernando earthquake as a propagating rupture in a half-space, using for the slip-time-history on the fault plane analytical expressions which approximate the slip functions of dynamic crack models obtained by Das and Aki (1977a, b). We synthesize the strong ground motions and accelerations at the Pacoima Dam site and compute the teleseismic signals for different models of cracks. Three major featuras of the data–the strong pulse associated with the beginning of the rupture, the high acceleration phase on the Pacoima Dam records, and the presence of ripples on the teleseismic seismograms–which are not compatible with a smooth rupture process, are well explained by a crack with barriers model where the rupture encounters, along the fault plane, barriers or obstacles of high strength materials which may remain unbroken after the passage of the rupture front. A high-stress drop (400 to 500 bars) is required in the hypocentral area to explain the high-amplitude short-duration first pulse of the teleseismic records. This indicates a high level of tectonic stress in the area. A study of the earthquake series following the main shock shows that the aftershocks which took place in the region where major slipping occurred during the earthquake may represent the release of some of the barriers.

Short fatigue crack initiation and growth modeling in aluminum 7075-T6

2014 ◽  
Vol 229 (7) ◽  
pp. 1206-1214 ◽  
Author(s):  
M Amiri ◽  
M Modarres
Keyword(s):  
Crack Initiation ◽  
Damage Mechanics ◽  
Fatigue Crack Initiation ◽  
Estimation Method ◽  
Continuum Damage Mechanics ◽  
Fatigue Tests ◽  
Short Cracks ◽  
Al 7075 ◽  
Edge Notch ◽  
Aluminum 7075

A series of fatigue tests is carried out to investigate the behavior of microcrack initiation and propagation in Al 7075-T6. Plate specimens with semi-circular single edge notch are tested under uniaxial loading at different load amplitudes. Optical microscopy is used to detect the initiation and growth of short cracks. Continuum damage mechanics is used to model the crack initiation. After the initiation, crack growth is studied using fracture mechanics models. For both regions of crack initiation and growth, Bayesian estimation method is used to account for uncertainties in the parameters of the model. Results of the entire fatigue life, including initiation and growth, are compared with experiments. Good agreement is observed.

Dynamic Failure Mechanisms in Beryllium-Bearing Bulk Metallic Glasses

1998 ◽  
Vol 554 ◽  
Author(s):  
David M. Owen ◽  
Ares J. Rosakis ◽  
William L. Johnson
Keyword(s):  
Crack Initiation ◽  
Shear Band ◽  
Metallic Glasses ◽  
Impact Loading ◽  
High Speed ◽  
Failure Mechanisms ◽  
Shear Bands ◽  
Dynamic Crack ◽  
Dynamic Failure ◽  
Asymmetric Impact

AbstractThe understanding of dynamic failure mechanisms in bulk metallic glasses is important for the application of this class of materials to a variety of engineering problems. This is true not only for design environments in which components are subject to high loading rates, but also when components are subjected to quasi-static loading conditions where observations have been made of damage propagation occurring in an unstable, highly dynamic manner. This paper presents preliminary results of a study of the phenomena of dynamic crack initiation and growth as well as the phenomenon of dynamic localization (shear band formation) in a beryllium-bearing bulk metallic glass, Zr41.25Ti13.75Ni10Cu12.75Be22.5. Pre-notched and prefatigued plate specimens were subjected to quasi-static and dynamic three-point bend loading to investigate crack initiation and propagation. Asymmetric impact loading with a gas gun was used to induce dynamic shear band growth. The mechanical fields in the vicinity of the dynamically loaded crack or notch tip were characterized using high-speed optical diagnostic techniques. The results demonstrated a dramatic increase in the crack initiation toughness with loading rate and subsequent crack tip speeds approaching 1000 m s−1. Dynamic crack tip branching was also observed under certain conditions. Shear bands formed readily under asymmetric impact loading. The shear bands traveled at speeds of approximately 1300 m s−1 and were accompanied by intense localized heating measured using high-speed full-field infrared imaging. The maximum temperatures recorded across the shear bands were in excess of 1500 K.

A New Approach for Fatigue Damage Modeling of Subsurface-Initiated Spalling in Large Rolling Contacts

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Aditya A. Walvekar ◽  
Neil Paulson ◽  
Farshid Sadeghi ◽  
Nick Weinzapfel ◽  
Martin Correns ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Damage Mechanics ◽  
Numerical Models ◽  
Rolling Contact ◽  
Fe Model ◽  
Triangle Mesh ◽  
Computationally Efficient ◽  
New Approach ◽  
Rolling Contacts ◽  
Delaunay Triangle

Large bearings employed in wind turbine applications have half-contact widths that are usually greater than 1 mm. Previous numerical models developed to investigate rolling contact fatigue (RCF) require significant computational effort to study large rolling contacts. This work presents a new computationally efficient approach to investigate RCF life scatter and spall formation in large bearings. The modeling approach incorporates damage mechanics constitutive relations in the finite element (FE) model to capture fatigue damage. It utilizes Voronoi tessellation to account for variability occurring due to the randomness in the material microstructure. However, to make the model computationally efficient, a Delaunay triangle mesh was used in the FE model to compute stresses during a rolling contact pass. The stresses were then mapped onto the Voronoi domain to evaluate the fatigue damage that leads to the formation of surface spall. The Delaunay triangle mesh was dynamically refined around the damaged elements to capture the stress concentration accurately. The new approach was validated against previous numerical model for small rolling contacts. The scatter in the RCF lives and the progression of fatigue spalling for large bearings obtained from the model show good agreement with experimental results available in the open literature. The ratio of L10 lives for different sized bearings computed from the model correlates well with the formula derived from the basic life rating for radial roller bearing as per ISO 281. The model was then extended to study the effect of initial internal voids on RCF life. It was found that for the same initial void density, the L10 life decreases with the increase in the bearing size.

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