Methods for Theoretical Assessment of Delamination Risks in Electronic Packaging

2017 ◽  
Author(s):  
Torsten Hauck ◽  
Ilko Schmadlak ◽  
Nishant Lakhera ◽  
Sandeep Shantaram ◽  
David Samet ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Electronic Packaging ◽  
Bulk Material ◽  
Material Model ◽  
Simulation Method ◽  
Critical Energy ◽  
Failure Criteria ◽  
Electronic Packages ◽  
Element Analysis ◽  
Advantages And Disadvantages

Fracture mechanics is an essential field of study towards the improvement and development of electronic packages. In combination with modern simulation method such as finite element analysis (FEA), fracture mechanics is widely used and appreciated in the industry. Many different approaches have been developed to calculate the fracture parameters for interfaces or bulk material under given loads in order to compare them against previously measured failure criteria. While many publications are available that have described the different simulation approaches in detail or compare the different fracture test methods, there have been few comparisons of these simulation approaches with respect to their use in research and development of electronic packages. The objective of this work is to compare different delamination modeling methodologies and their applications for electronic packaging. The work highlights the differences in theory behind each approach as well as the differences in their practical use to predict delamination or asses a fracture risk in electronic packages. The intention was to use commercially available FE-codes in conjunction with a well-defined set of adhesion strength tests. During this work, energy based fracture criteria were applied by means of the virtual crack closure technique (VCCT), the J-integral and the cohesive zone material model (CZM) methods. These methodologies are most commonly used but can differ significantly from each other as will be shown in this comparison. To demonstrate the use of these techniques, copper lead frame to epoxy mold compound (EMC) delamination was assessed, representing a very common packaging failure mode. Critical energy release rates were measured on multiple Copper-EMC test specimens under varying load phase angles. ANSYS was used to build mechanical simulation models of a selected device. Existing post processing procedures were applied to assess delamination risk based on above mentioned techniques. The simulation study considers realistic monotonic loading conditions and results will also be compared to existing failure analysis images for demonstration and validation purpose. As an outcome, the paper will include a ranking of the approaches as well as a summary of advantages and disadvantages, based method and accuracy. An outlook on future developments such as fatigue or aging phenomena will finish the work.

Accuracy of Failure Criteria Commonly Used for Ship Collision Simulations

2018 ◽  
Author(s):  
R. Villavicencio ◽  
Bin Liu ◽  
Kun Liu
Keyword(s):  
Finite Element ◽  
Failure Criteria ◽  
Small Scale ◽  
Finite Element Models ◽  
Impact Loads ◽  
Large Scatter ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
Ship Collision ◽  
Double Hull

The paper summarises observations of the fracture response of small-scale double hull specimens subjected to quasi-static impact loads by means of simulations of the respective experiments. The collision scenarios are used to evaluate the discretisation of the finite element models, and the energy-responses given by various failure criteria commonly selected for collision assessments. Nine double hull specimens are considered in the analysis so that to discuss the advantages and disadvantages of the different failure criterion selected for the comparison. Since a large scatter is observed from the numerical results, a discussion on the reliability of finite element analysis is also provided based on the present study and other research works found in the literature.

Effects of Negative Biaxial Loadings and Notch on Failure Assessment Diagrams

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
K. Ragupathy ◽  
K. Ramesh ◽  
D. Hall
Keyword(s):  
Finite Element ◽  
Fracture Mechanics ◽  
Biaxial Loading ◽  
Failure Criteria ◽  
Small Scale ◽  
J Integral ◽  
Element Analysis ◽  
Worst Case ◽  
Failure Assessment ◽  
The Impact

The failure assessment diagram (FAD) is a simplified and robust flaw assessment methodology, which simultaneously connects two dominant failure criteria: linear elastic fracture mechanics on one end and plastic collapse on the other end. This interaction is in the realm of elastic-plastic fracture mechanics. It is popularly known as the R6 approach, which graphically characterizes the impact of plasticity on crack driving force. In recent years, there has been continuous interest in using FADs to assess the failure of cracked structures subjected to biaxial loadings. Biaxiality is defined as the ratio of stress applied parallel and normal to the crack. Some pressure loaded aircraft components operate under negative biaxial ratios up to −0.5. In this paper, a detailed study on FAD was conducted using finite element analysis computed J-integral methods to investigate the effect of biaxial loading using different FAD approaches for geometries with notches. Geometries with a crack that emanates at a fillet region were simulated with various biaxial loading ratios from −0.5 to +0.5 using 2014-T6 material. FAD curves were numerically generated for cracks at notched regions subjected to various biaxial loadings using J-integral values from finite element analyses. These results were compared with standard FAD approaches. All comparison studies were made between uniaxial and biaxial loading cases with FAD curves created using four different crack sizes. Under small scale yielding, this study clearly shows that FAD curves are not influenced by negative biaxial loading at low load (up to 40% of yield strength). It was clearly confirmed that the majority of previously developed analytical FAD curves do not effectively account for notch and plasticity effects due to negative biaxiality. Based on this study, tension normal to the crack and compression parallel to the crack is the worst combination, and it has a very pronounced effect on FAD curve shapes. The standard analytical FAD curves are nonconservative compared with the approach recommended here, particularly under the worst case condition. FAD curves developed are shown to predict lower failure loads as compared with the currently accepted analytical FAD approaches defined in existing standards, e.g., R6 and API 579. The impact of negative biaxial loading can be investigated directly using a J-integral FAD approach but can be compared with ease by plotting both approaches in a FAD format.

Improving failure sub-models in an orthotropic plasticity-based material model

2020 ◽  
pp. 002199832098265
Author(s):  
Loukham Shyamsunder ◽  
Bilal Khaled ◽  
Subramaniam D Rajan ◽  
Gunther Blankenhorn
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
High Speed ◽  
Simulation Models ◽  
Material Model ◽  
Failure Criteria ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
Static Tensile

Theoretical details of two failure criteria implemented in an orthotropic plasticity model are presented. Improvements to the well-known Puck Failure criterion and a recently developed Generalized Tabulated Failure criterion are used to illustrate how to link a failure sub-model to existing deformation and damage sub-models in the context of explicit finite element analysis. These models are implemented in LS-DYNA, a commercial transient dynamic finite element code. Two validation tests are used to evaluate the failure sub-model implementation and improvements - a stacked-ply test carried out at room temperature under quasi-static tensile and compressive loadings, and a high-speed, projectile impact test where there is significant damage and material failure of the impacted panel. Results indicate that developed procedures and improvements provide the analyst with a reasonable and systematic approach to building predictive impact simulation models.

scholarly journals Numerical Simulation on Dynamic Behavior of Slab–Column Connections Subjected to Blast Loads

2021 ◽  
Vol 11 (16) ◽  
pp. 7573
Author(s):  
Kwang Mo Lim ◽  
Taek Hee Han ◽  
Joo Ha Lee
Keyword(s):  
Numerical Analysis ◽  
Blast Resistance ◽  
Mesh Size ◽  
Material Model ◽  
Simulation Method ◽  
Blast Load ◽  
Blast Loads ◽  
Element Analysis ◽  
Model And Simulation ◽  
Resistance Performance

Although many studies on the blast-resistant performance of structures have focused mainly on single members such as beams and columns, there is little research on the behavior of joints that are subjected to blast loads. In this study, the structural behavior of a slab–column connection subjected to blast load was investigated using a numerical analysis method. LS-DYNA was used as a finite element analysis program, and in order to improve the accuracy of numerical analysis, mesh size, material model, and simulation method of blast load were determined through preliminary analysis. The effect of different restraints of the joints, depending on the position of the columns in the slab, on the blast resistance performance was investigated. As a result, the highly confined slab-interior column connection showed better behavior than other edge and corner columns. The drop panel installed between the lower column and the slab was effective in improving the blast-resistance performance of the slab–column connection. For a more accurate evaluation of blast resistance performance, it was suggested that various evaluation factors such as ductility ratio, reinforcing stress, and concrete fracture area can be considered along with the support rotation, which is an important evaluation factor suggested by many standards.

Assessment of Failure Modeling With Thinning Strain Criterion in LS-DYNA

2003 ◽  
Author(s):  
Ching-Shan Cheng
Keyword(s):  
Failure Criterion ◽  
Material Model ◽  
Failure Criteria ◽  
Material Failure ◽  
Strain Criterion ◽  
Element Analysis ◽  
Material Models ◽  
Ductile Materials ◽  
Failure Modeling ◽  
Nonlinear Nature

Element deletion based on various failure criteria has been implemented in commercial finite element analysis packages, e.g. LS-DYNA. However, due to the localized and nonlinear nature of the material failure, especially for the ductile materials, a good failure criterion needs to be robust for different mesh definitions and loading conditions. In the present work, the material model with enhanced failure criterion in LS-DYNA, material type 123 (MAT123), is investigated. The equations for determining the parameter of the thinning strain failure criterion are derived based on the assumptions that Yeh et al. [7] proposed. Simulations of different tests using MAT123 with the thinning strain at failure calculated show better correlation with the experimental results than the other material models examined.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

scholarly journals Optimization Study of Post-Weld Heat Treatment for 12Cr1MoV Pipe Welded Joint

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Zichen Liu ◽  
Xiaodong Hu ◽  
Zhiwei Yang ◽  
Bin Yang ◽  
Jingkai Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Simulation Method ◽  
Post Weld Heat Treatment ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Tempering Treatment ◽  
Temper Heat Treatment ◽  
Weld Heat

In order to clarify the role of different post-weld heat treatment processes in the manufacturing process, welding tests, post-weld heat treatment tests, and finite element analysis (FEA) are carried out for 12C1MoV steel pipes. The simulated temperature field and residual stress field agree well with the measured results, which indicates that the simulation method is available. The influence of post-weld heat treatment process parameters on residual stress reduction results is further analyzed. It is found that the post weld dehydrogenation treatment could not release residual stress obviously. However, the residual stress can be relieved by 65% with tempering treatment. The stress relief effect of “post weld dehydrogenation treatment + temper heat treatment” is same with that of “temper heat treatment”. The higher the temperature, the greater the residual stress reduction, when the peak temperature is at 650–750 °C, especially for the stress concentration area. The longer holding time has no obvious positive effect on the reduction of residual stress.

Cord/Rubber Material Properties

1985 ◽  
Vol 58 (4) ◽  
pp. 830-856 ◽  
Author(s):  
R. J. Cembrola ◽  
T. J. Dudek
Keyword(s):  
Finite Element ◽  
Material Model ◽  
Rubber Composites ◽  
Stress Strain ◽  
Element Analysis ◽  
Rubber Layer ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Interlaminar Shear ◽  
Mechanics Of Composite Materials

Abstract Recent developments in nonlinear finite element methods (FEM) and mechanics of composite materials have made it possible to handle complex tire mechanics problems involving large deformations and moderate strains. The development of an accurate material model for cord/rubber composites is a necessary requirement for the application of these powerful finite element programs to practical problems but involves numerous complexities. Difficulties associated with the application of classical lamination theory to cord/rubber composites were reviewed. The complexity of the material characterization of cord/rubber composites by experimental means was also discussed. This complexity arises from the highly anisotropic properties of twisted cords and the nonlinear stress—strain behavior of the laminates. Micromechanics theories, which have been successfully applied to hard composites (i.e., graphite—epoxy) have been shown to be inadequate in predicting some of the properties of the calendered fabric ply material from the properties of the cord and rubber. Finite element models which include an interply rubber layer to account for the interlaminar shear have been shown to give a better representation of cord/rubber laminate behavior in tension and bending. The application of finite element analysis to more refined models of complex structures like tires, however, requires the development of a more realistic material model which would account for the nonlinear stress—strain properties of cord/rubber composites.

Thermo-Mechanical Modeling and Analysis of Equal Channel Angular Pressing

2005 ◽  
Vol 23 ◽  
pp. 263-266 ◽  
Author(s):  
Qing Xiang Pei ◽  
B.H. Hu ◽  
C. Lu
Keyword(s):  
Equal Channel Angular Pressing ◽  
Temperature Rise ◽  
Flow Behavior ◽  
Material Model ◽  
Workpiece Material ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Die Geometry ◽  
Angular Pressing ◽  
Good Agreement

Thermo-mechanical finite element analysis was carried out to study the deformation behavior and temperature distribution during equal channel angular pressing (ECAP). The material model used is the Johnson-Cook constitution model that can consider the multiplication effect of strain, strain rate, and temperature on the flow stress. The effects of pressing speed, pressing temperature, workpiece material and die geometry on the temperature rise and flow behavior during ECAP process were investigated. The simulated temperature rise due to deformation heating was compared with published experimental results and a good agreement was obtained. Among the various die geometries studied, the two-turn die with 0° round corner generates the highest and most uniform plastic strain in the workpiece.

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