Stress Analysis of Thermal Inclusions With Interior Voids and Cracks

1999 ◽  
Vol 122 (3) ◽  
pp. 192-199 ◽  
Author(s):  
C. Q. Ru
Keyword(s):  
Stress Analysis ◽  
Thermal Stresses ◽  
Homogeneous Medium ◽  
Practical Interest ◽  
Dissimilar Materials ◽  
Geometrical Shape ◽  
Thermal Mismatch ◽  
Structural Element ◽  
Interconnect Lines ◽  
Thermal Inclusion

Thermal mismatch induced residual stresses are identified as one of the major causes of voiding and failure of some critical components in electronic packaging, such as passivated interconnect lines and isolation trenches. In this paper, a general method is presented for thermal stress analysis of an embedded structural element in the presence of internal or nearby voids and cracks. Here, the elastic mismatch between dissimilar materials is ignored. Hence, the embedded structural element is modeled as a thermal inclusion of arbitrary shape surrounded by an infinite elastic medium of the same elastic constants. Thermal stresses are caused by thermal mismatch between the inclusion and the surrounding material due to a uniform change in temperature. With the present method, the problem is reduced to one of an infinite homogeneous medium containing the same voids and cracks, subjected to a set of remote stresses determined by the geometrical shape of the thermal inclusion. In particular, the remote stresses are uniform when the thermal inclusion is an ellipse. The method gives an elementary expression for the internal stress field of a thermal inclusion with a single interior void or crack. Several examples of practical interest are used to illustrate the method. The results show that an internal void or crack can significantly change stress distribution within the inclusion and gives rise to stress concentration around the void or crack. [S1043-7398(00)00303-0]

scholarly journals An Elastoplastic Thermal-Stress Analysis of a Free Plate

1956 ◽  
Vol 23 (3) ◽  
pp. 395-402
Author(s):  
Jerome Weiner
Keyword(s):  
Thermal Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Uniqueness Theorem ◽  
Unique Solution ◽  
Heat Input ◽  
Thermal Stresses ◽  
Elastoplastic Material ◽  
Heuristic Solution ◽  
Peak Magnitude

Abstract The thermal stresses in a free plate of elastoplastic material subjected to a varying heat input over one face are determined. A heuristic solution is first found by suitable modifications of the known elastic solution. It is then verified that the solution satisfies all the conditions of the appropriate uniqueness theorem and represents therefore the unique solution to the problem. Residual stresses are determined and found to depend markedly on the peak magnitude of the heat input.

scholarly journals Thermal Effect on Structural Interaction between Energy Pile and Its Host Soil

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Qingwen Li ◽  
Lu Chen ◽  
Lan Qiao
Keyword(s):  
Thermal Stresses ◽  
Heat Transfer Process ◽  
Structural Element ◽  
Energy Pile ◽  
Structural Interaction ◽  
Comprehensive Method ◽  
Green Power ◽  
Energy Piles ◽  
Distribution Of Stress ◽  
Peak Value

Energy pile is one of the promising areas in the burgeoning green power technology; it is gradually gaining attention and will have wide applications in the future. Because of its specific structure, the energy pile has the functions of both a structural element and a heat exchanger. However, most researchers have been paying attention to only the heat transfer process and its efficiency. Very few studies have been done on the structural interaction between the energy pile and its host soil. As the behavior of the host soil is complicated and uncertain, thermal stresses appear with inhomogeneous distribution along the pile, and the peak value and distribution of stress will be affected by the thermal and physical properties and thermal conductivities of the structure and the host soil. In view of the above, it is important to determine thermal-mechanical coupled behavior under these conditions. In this study, a comprehensive method using theoretical derivations and numerical simulation was adopted to analyze the structural interaction between the energy pile and its host soil. The results of this study could provide technical guidance for the construction of energy piles.

Structural Design of the Geometrical Shape of Interfaces in Bonded Dissimilar Materials Based on Theoretical Elastic Analysis

1999 ◽  
Vol 586 ◽  
Author(s):  
Masayoshi Tateno ◽  
Yasushi Fukuzawa ◽  
Shigeru Nagasawa ◽  
Hiroshi Sakuta
Keyword(s):  
Stress Distribution ◽  
Structural Design ◽  
Bonding Strength ◽  
Stress Singularity ◽  
Dissimilar Materials ◽  
Correlation Factor ◽  
Geometrical Shape ◽  
Elastoplastic Behavior ◽  
Secant Stiffness ◽  
The Relationship

ABSTRACTIn order to evaluate the practical strength of a joint and its fracture mode, it is important to find the stress distribution near the edge of the interface by analyses of strength and fracture. The index of stress singularity based on theoretical analysis is a useful tool to indicate the stress distribution.In this paper, investigations on the evaluation of the practical strength of bonded dissimilar materials based on the stress singularity are carried out. The secant stiffness module, which was used for plastics analysis, was applied to the evaluation of thermal elastoplastic behavior near the interface. Spherical conditions of the interface shape were used for the evaluation of stress behavior and the experiment of bonding strength. The relationship between the index of stress singularity, λ, and the practical strength of the bonded TiB2-Ni system was investigated by comparing theoretical λ, which was determined by substituting the secant stiffness module into Bogy's eigenequation, with the practical strength in the edge angle of the interface between 60° and 90° The correlation factor of the relationship between λ and the practical bonding strength of the TiB2-Ni system was found positive. These results show that the structural design of a geometrical interface which is getting a higher strength joint based on the index of stress singularity is verified experimentally.

Comparison of Thermal and Stress Analysis Results for a High Voltage Module Using FEA and a Quick Parametric Analysis Tool

2018 ◽  
Author(s):  
L. M. Boteler ◽  
S. M. Miner
Keyword(s):  
Stress Analysis ◽  
High Voltage ◽  
Parametric Analysis ◽  
Thermal Stresses ◽  
Analysis Tool ◽  
Element Analysis ◽  
Module Design ◽  
Fast Running ◽  
Packaging Structure ◽  
Low Order

A low order fast running parametric analysis tool, ParaPower, was used to arrive at the design for a novel high voltage module. The low order model used a 3D nodal network to calculate device temperatures and thermal stresses. The model assumed heat flux generated near the top surface of each device which is then conducted through the packaging structure and removed by convection. The temperature distribution is used to calculate thermal stresses throughout the package. This co-design modeling tool, developed for rectilinear geometries, allowed a rapid evaluation of the package temperatures and CTE induced stresses throughout the design space. However, once the final design configuration was determined a detailed finite element analysis was performed to validate the design. This paper compares the results obtained using ParaPower to the FEA, demonstrating the usefulness of the parametric analysis tool. Results for both temperature and CTE induced stress are compared. Two different stress models are evaluated. One based on the more traditional planar module design, which assumes a substantial substrate or heat spreader on which the module is assembled. The other model is less restrictive, eliminating the requirement for a substrate. The FEA modeling was performed using SolidWorks beginning with a thermal analysis followed by a stress analysis based on the temperature solution. Both the values and the trends of the temperatures and stresses were evaluated. The temperature results agreed to within 3.2°C. The trends and sign of the stresses were correctly predicted, but the magnitudes were not. One of the significant advantages of ParaPower is the speed of the computation. The run time for the parametric analysis was roughly two orders of magnitude faster than the FEA. This made it possible to build the model and complete the parametric analysis of roughly 500 runs in less than a day.

scholarly journals Thermal Elastic-Plastic Stress Analysis of an Aluminium Composite Disc under Linearly Decreasing Thermal Loading

2008 ◽  
Vol 17 (3) ◽  
pp. 096369350801700 ◽  
Author(s):  
Muzaffer Topcu ◽  
Gurkan Altan ◽  
Hasan Callioglu ◽  
Burcin Deda Altan
Keyword(s):  
Thermal Stress ◽  
Stress Analysis ◽  
Tangential Stress ◽  
Outer Surface ◽  
Thermal Stresses ◽  
Stress Component ◽  
Aluminium Composite ◽  
Hardening Material ◽  
Elastic Plastic ◽  
Inner Surface

In this study, an elastic-plastic thermal stress analysis of an orthotropic aluminium metal matrix composite disc with a hole has been investigated analytically for non-linear hardening material behaviour. The aluminium composite disc reinforced curvilinearly by steel fibres is produced under hydraulic press. The mechanical properties of the composite disc are obtained by tests. A computer program is developed to calculate the thermal stresses under a linearly decreasing temperature from inner surface to outer surface. Elastic, elastic-plastic and residual thermal stress distributions are obtained analytically from inner surface to outer surface and they are presented in tables and Fig. s. The elastic-plastic solution is performed for the plastic region expanding around the inner surface. The magnitude of the tangential stress component has been found out in this study to be higher than the magnitude of the radial stress component. Besides, the tangential stress component is compressive at the inner surface and tensile at the outer surface. The magnitude of the tangential residual stress component is the highest at the inner surface of the composite disc.

Thermal Stress Measurement of Solder Joints in BGA Packages: Theoretical and Experimental

2008 ◽  
Author(s):  
H. X. Shang ◽  
J. X. Gao ◽  
P. I. Nicholson
Keyword(s):  
Thermal Stresses ◽  
Solder Joints ◽  
Stress Measurement ◽  
Closed Form Solution ◽  
Dissimilar Materials ◽  
Form Solution ◽  
Bga Packages ◽  
Reliability Characteristics ◽  
Bga Package ◽  
Graded Interlayer

In this study, an analytical model to obtain a closed-form solution for thermomechanical behaviours of BGA (Ball Grid Array) package was derived and experimentally validated. In the theoretical analysis, the BGA package was represented by a three-layer axisymmetrical model: two layers of dissimilar materials jointed by a graded interlayer. Based on the classical bending theory, the thermal stresses induced by temperature changes were calculated accurately. 2-D FE (Finite Element) meshes of BGA packages subjected to high temperature were used to verify the theoretical solutions. Furthermore, two types of BGA samples, each with eutectic (63wt%Sn/37wt%Pb) and Pb-free SAC387 (95.5wt%Sn/3.8wt%Ag/0.7wt%Cu) solder joints respectively, were experimentally investigated by high resolution Moire´ Interferometry (MI). Thermal cycling tests were performed on each package with temperature variation from 25°C to 125°C. It was found that the thermal deformation obtained from moire´ tests matched well with those from analytical solutions and FE analyses. Based on the shear strain values, the reliability characteristics of BGA assemblies were also assessed.

Comparative Study Between FEA-Based Sequentially-Coupled and Fully-Coupled Thermal Stress Models in a Laser Hardening Process

2013 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay ◽  
Joseph Connors
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Stress Analysis ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Preliminary Investigation ◽  
Hardening Process ◽  
Structural Loading ◽  
Laser Transformation Hardening ◽  
Fully Coupled

Numerous mathematical investigations of laser transformation hardening process have been conducted in the past three decades. The commonly used strategy of a sequentially coupled temperature-stress analysis is to first obtain temperature results from the temperature elements in a thermal loading model, followed by the calculations of thermal stresses from the structural elements under structural loading. Temperature is used as a predefined variable (varies with position and time only) as it is assumed to not change by the stress analysis. Fully coupled thermal-stress analysis is needed when the stress analysis is dependent on the temperature distribution and the temperature distribution depends on the stress solution This paper compares these two finite element (FE) based approaches for modeling temperature and thermal stress evolution in laser transformation hardening of hypoeutectoid steels. The dependence of temperature results on stresses and vice versa at higher temperatures involving significant inelastic strains has been demonstrated. Preliminary investigation reveals that under such circumstances thermal and mechanical solutions must be obtained simultaneously rather than sequentially.

scholarly journals Numerical analysis of thermal stresses in welded joint smade of steels X20 and X22

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 121-126 ◽  
Author(s):  
Sasa Mladenovic ◽  
Vera Sijacki-Zeravcic ◽  
Gordana Bakic ◽  
Jasmina Lozanovic-Sajic ◽  
Marko Rakin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Finite Element Method ◽  
Thermal Stresses ◽  
Welded Joint ◽  
Dissimilar Materials ◽  
Post Weld Heat Treatment ◽  
The Finite Element Method ◽  
Steam Pipeline ◽  
Transition Piece ◽  
Critical Regions

Stress calculation of steam pipeline is presented, focused on the welded joint. Numerical calculation was performed using the finite element method to obtain stress distribution in the welded joint made while replacing the valve chamber. Dissimilar materials were used, namely steel 10CrMoV9-10 according to EN 10216-2 for the valve chamber, the rest of steam pipeline was steel X20, whereas the transition piece material was steel X22. Residual stresses were calculated, in addition to design stresses, indicating critical regions and necessity for post-weld heat treatment.

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