Strength Evaluation of Notch Structure for Semiconductor Encapsulant Resin

2002 ◽  
Vol 124 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Noriyasu Kawamura ◽  
Takashi Kawakami ◽  
Kikuo Kishimoto ◽  
Masaki Omiya ◽  
Toshikazu Shibuya
Keyword(s):  
Stress Distribution ◽  
Critical Stress ◽  
Epoxy Resins ◽  
Fracture Behavior ◽  
Stress Distributions ◽  
Strength Evaluation ◽  
Notched Specimens ◽  
Fracture Tests ◽  
Notch Tip ◽  
Semiconductor Encapsulant

Plastic encapsulated semiconductor packages may crack at the corner regions of die pads or chips if internal delamination occurs at an elevated temperature during the reflow soldering process. Thus, the structural strength design around the notch structures, which will be formed in the encapsulant resin due to the delamination, is considered one of the most important issues. Especially, it becomes a more critical item of the package development in order to realize the reflow process with lead-free solder materials, whose melting points are higher than that of Sn63-Pb37. In this study, the fracture behavior of notched specimens, which were made of silica particulate-filled epoxy resins and modeled as the corner regions in actual packages, were studied with experimental and numerical analyses. First, the fracture tests of the notch structure of semiconductor encapsulant resin were carried out. A notch tip with several different radii was introduced to the specimen. The specimens were fractured by a three-point bending load. Second, the strength evaluation of the notch structure was carried out. The critical stress distribution σCr=max.[KIC/2πr1/2,σB] was used to determine the crack initiation at the notch tip. It is assumed that a fracture occurs when, at any point near the notch tip, the stress distribution exceeds the critical stress distribution determined by fracture toughness and bending strength. Three-dimensional finite element analysis was carried out to obtain the stress distributions around the notch tip in the specimen. The calculated stress distributions around the notch tip were compared with the critical stress distribution to estimate the fracture load of the specimen. Estimated fracture loads at room temperature and at high temperature were compared with the results of the fracture tests. It was confirmed that the predicted results based on the critical stress distribution corresponded very well with the experimental results. The validity of the criterion was confirmed by studying the fracture behavior of the notched specimens of actual silica particulate filled epoxy resins.

Finite Element Analysis of Poor Distal Contact of the Femoral Component of a Cementless Hip Endoprosthesis

1993 ◽  
Vol 207 (4) ◽  
pp. 255-261 ◽  
Author(s):  
M Taylor ◽  
E W Abel
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Influencing Factor ◽  
Three Dimensional ◽  
Stress Distributions ◽  
Element Analysis ◽  
Hip Endoprosthesis ◽  
Applied Loading ◽  
Femoral Geometry ◽  
Contact Models

The difficulty of achieving good distal contact between a cementless hip endoprosthesis and the femur is well established. This finite element study investigates the effect on the stress distribution within the femur due to varying lengths of distal gap. Three-dimensional anatomical models of two different sized femurs were generated, based upon computer tomograph scans of two cadaveric specimens. A further six models were derived from each original model, with distal gaps varying from 10 to 60 mm in length. The resulting stress distributions within these were compared to the uniform contact models. The extent to which femoral geometry was an influencing factor on the stress distribution within the bone was also studied. Lack of distal contact with the prosthesis was found not to affect the proximal stress distribution within the femur, for distal gap lengths of up to 60 mm. In the region of no distal contact, the stress within the femur was at normal physiological levels associated with the applied loading and boundary conditions. The femoral geometry was found to have little influence on the stress distribution within the cortical bone. Although localized variations were noted, both femurs exhibited the same general stress distribution pattern.

Computer Simulation of Fracture in Brittle Polycrystalline Solids: Effect of Modulus Amisotropy

1992 ◽  
Vol 291 ◽  
Author(s):  
Shiun Ling ◽  
Michael P. Anderson
Keyword(s):  
Fracture Behavior ◽  
Careful Analysis ◽  
Fracture Morphology ◽  
Constitutive Relationship ◽  
Stress Distributions ◽  
Compliance Matrix ◽  
Spring Network Model ◽  
Polycrystalline Solids ◽  
D Model ◽  
Crystalline Symmetry

ABSTRACTA simulation procedure based on the spring network model has been developed for studying the fracture behavior in brittle, polycrystalline solids. In this 2-D model, the effect of crystalline symmetry is accounted for by imparting to individual bonds a constitutive relationship using the material compliance matrix. Using this model, it was found that the fracture morphology becomes more intragranular in nature with increasing modulus anisotropy. Careful analysis suggests that this is due to the wider stress distributions, and the resulting larger number of cracks generated in the interior of anisotropic grains.

Application of the Strain Energy Density Criterion to the Estimation of Fracture Loads in Structural Steel S355J2 at Lower Shelf Temperatures

2017 ◽  
Author(s):  
Sergio Cicero ◽  
Francisco Ibáñez ◽  
Isabela Procopio ◽  
Virginia Madrazo
Keyword(s):  
Energy Density ◽  
Structural Steel ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Input Parameter ◽  
Fracture Load ◽  
Notched Specimens ◽  
Fracture Tests ◽  
Material Fracture ◽  
Cracked Specimens

This paper presents the application of the Strain Energy Density (SED) criterion to the estimation of fracture loads on structural steel S355J2 operating at lower shelf temperatures (−196°C) and containing U-shaped notches. 24 fracture tests were performed on this material, combining 6 different notch radii: 0 mm (crack-like defect), 0.15 mm, 0.25 mm, 0.50 mm, 1.0 mm and 2.0 mm. The results obtained in cracked specimens (0 mm notch radius) were used to determine the material fracture toughness, which is an input parameter in the SED criterion, whereas the notched specimens were used to demonstrate the capacity and the limitations of the SED criterion to provide fracture load estimations in the analyzed conditions.

Effect of Flaw Dimensions on Ductile Fracture Behavior of Non-Aligned Multiple Flaws in a Plate

2011 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito
Keyword(s):  
Ductile Fracture ◽  
Flat Plate ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Surface Flaws ◽  
Fracture Tests ◽  
The Difference ◽  
Almost All ◽  
Maximum Minimum

The fitness-for-service codes require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw proximity rule. Worldwide, almost all such codes provide their own proximity rule, often with unclear technical bases of the application of proximity rule to ductile or fully plastic fracture. In particular, the effect of flaw dimensions of multiple surface flaws on fully plastic fracture of non-aligned multiple flaws had not been clear. To clarify the effect of the difference of part through-wall and through-wall flaws on the behavior of fully plastic fracture, the fracture tests of flat plate specimens with non-aligned multiple part through-wall flaws were conducted. When the flaw depth a was shallow with 0.4 in ratio of a to thickness t, the maximum load Pmax occurred at penetration of multiple flaws and the effect of vertical distance of non-aligned multiple flaws H on Pmax was not so significant. However, when flaw depth was deep with 0.8 in a/t, Pmax occurred after penetration of flaws and the effect of H on Pmax could be seen clearly. It was judged that the through-wall flaw tests were appropriate for discussion of the effect of H on Pmax and the alignment rule of multiple flaws. In addition, in order to clarify the appropriate length parameter to estimate Pmax of test specimens with dissimilar non-aligned through-wall multiple flaws, the fracture tests of plate specimens were also conducted. The effect of different flaw length on Pmax was discussed with maximum, minimum and averages of dissimilar non-aligned multiple flaw lengths. Experimental results showed that the maximum length lmax would be an appropriate length parameter to estimate Pmax, when the non-aligned multiple through-wall flaws were dissimilar.

Stress Distribution Analysis of Different Types of Blade for a Fermentation System

2013 ◽  
Vol 479-480 ◽  
pp. 319-323
Author(s):  
Cheng Chi Wang ◽  
Po Jen Cheng ◽  
Kuo Chi Liu
Keyword(s):  
Stress Distribution ◽  
Maximum Stress ◽  
Effective Means ◽  
Materials Processing ◽  
Distribution Analysis ◽  
Stress Distributions ◽  
Fermentation System ◽  
Different Types ◽  
Inclined Angle ◽  
Key Parameter

Fermentation system is widely used for food manufacturing, materials processing and chemical reaction etc. Different types of blade in the tank for fermentation cause distinct stress distributions on the surface between fluid and blade, and appear various flow fields in the tank. So, this paper is mainly focused on analyzing the stress field of blades under different scales of blade with fixing rotational speed. The results show that the ratio of blade length to width influences stress distribution on the blades. At the same time, the inclined angle of blade is also the key parameter for the consideration of design and appropriate design will decrease the maximum stress. The results provide an effective means of gaining insights into the stress distribution of fermentation system.

Simple Model for Contact Stress of Strands Bent over Circular Saddles

2016 ◽  
Author(s):  
Sherif Mohareb ◽  
Arndt Goldack ◽  
Mike Schlaich
Keyword(s):  
Simple Model ◽  
Stress Distribution ◽  
Contact Force ◽  
Contact Stress ◽  
Flexural Rigidity ◽  
Strong Nonlinearity ◽  
Stress Distributions ◽  
Maximum Contact ◽  
Contact Stress Distribution ◽  
Peak Value

Cable-stayed and extra-dosed bridges are today widely used bridge types. Recently, saddles have been used to deviate strands of cables in the pylons. Up to now the mechanics of strands on saddles are not well understood. It was found, that typical longitudinal contact stress distributions between strand and saddle show a strong nonlinearity and a high peak value around the detachment point, where the strand meets the saddle. This paper presents a procedure to analyse the longitudinal contact stress distribution obtained by FEM calculations: This contact stress can be idealised as a constant contact stress according to the Barlow's formula and a contact force at the detachment point due to the flexural rigidity of the bent tension elements. An analytical model is provided to verify this contact force. Finally, a formula is presented to calculate the maximum contact stress. This study provides the basis for further research on saddle design and fatigue of strands.

Fracture assessment of polycarbonate parts produced by fused deposition modeling in the out-of-plane printing direction – effect of raster angle

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Iman Sedighi ◽  
Majid R. Ayatollahi ◽  
Bahador Bahrami ◽  
Marco A. Pérez-Martínez ◽  
Andrés A. Garcia-Granada
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Fracture Behavior ◽  
Fused Deposition Modeling ◽  
Mode I ◽  
Content Type ◽  
Fused Deposition ◽  
Out Of Plane ◽  
Deposition Modeling ◽  
Fracture Tests

Purpose The purpose of this paper is to study the Mode I fracture behavior of polycarbonate (PC) parts produced using fused deposition modeling (FDM). The focus of this study is on samples printed along the out-of-plane direction with different raster angles. Design/methodology/approach Tensile and Mode I fracture tests were conducted. Semi-circular bend specimens were used for the fracture tests, which were printed in four different raster patterns of (0/90), (15/−75) (30/−60) and (45/−45). Moreover, the finite element method (FEM) was used to determine the applicability of linear elastic fracture mechanics (LEFM) for the printed PC parts. The fracture toughness results, as well as the fracture path and the fracture surfaces, were studied to describe the fracture behavior of the samples. Findings Finite element results confirm that the use of LEFM is allowed for the tested PC samples. The fracture toughness results show that changing the direction of the printed rasters can have an effect of up to 50% on the fracture toughness of the printed parts, with the (+45/−45) and (0/90) orientations having the highest and lowest resistance to crack propagation, respectively. Moreover, except for the (0/90) orientation, the other samples have higher crack resistance compared to the bulk material. The fracture toughness of the tested PC depends more on the toughness of the printed sample, rather than its tensile strength. Originality/value The toughness and the energy absorption capability of the printed samples (with different raster patterns) were identified as the main properties affecting the fracture toughness of the AM PC parts. Because the fracture resistance of almost all the samples was higher than that of the base material, it is evident that by choosing the right raster patterns for 3D-printed parts, very high resistance to crack growth may be obtained. Also, using FEM and comparing the size of the plastic zones, it was concluded that, although the tensile curves show nonlinearity, LEFM is still applicable for the printed parts.

Steady-State stress distributions in circumferentially notched bars subjected to creep

1982 ◽  
Vol 17 (3) ◽  
pp. 123-132 ◽  
Author(s):  
K D Al-Faddagh ◽  
R T Fenner ◽  
G A Webster
Keyword(s):  
Steady State ◽  
Stress Distribution ◽  
Stress Index ◽  
Stress Distributions ◽  
Computer Solution ◽  
Time Intervals ◽  
Throat Region ◽  
Intermediate Time ◽  
State Stress ◽  
Good Agreement

The paper describes a procedure, based on a finite element method, for calculating directly the steady-state stress distribution in circumferentially notched bars subjected to creep without the need for obtaining solutions at intermediate time intervals. Good agreement is obtained with relevant approximate plasticity solutions and with numerical calculations which approach the steady-state over a period of time from the initial elastic stress distribution. Also, the procedure is equally applicable to primary, secondary, and tertiary creep, provided the variables of stress and time are separable in the creep law. Results obtained for a range of notch geometries and values of the stress index, n, are reported. It is found for each profile that a region of approximately constant effective stress, σ, independent of n, is obtained which can be used to characterise the overall behaviour of the notch throat region when a steady-state is reached sufficiently early in life. An approximate method for estimating the maximum equivalent steady-state stress across the notch throat is also presented which does not require a computer solution.

Study on fracture behavior for Sharp V-notched specimens combined with 3D-DIC and Caustics

2021 ◽  
pp. 108190
Author(s):  
Chen Huang ◽  
Ye Song ◽  
Liyun Yang ◽  
Ping Fan ◽  
Qingcheng Wang ◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Notched Specimens

Stress Distributions in Nonsymmetric Rotating Rays

1955 ◽  
Vol 22 (3) ◽  
pp. 311-316
Author(s):  
P. G. Hodge
Keyword(s):  
Plastic Deformation ◽  
Stress Distribution ◽  
Large Scale ◽  
Bending Moment ◽  
Rotating Disk ◽  
Longitudinal Force ◽  
Maximum Speed ◽  
Stress Distributions ◽  
Centrifugal Forces

Abstract The centrifugal forces acting upon a rotating ray will produce longitudinal stresses along the ray. If the ray is not symmetric, these stresses will result not only in a longitudinal force, but also in a bending moment. A technique for finding the stress distribution in this case is developed and illustrated by means of simple examples. The limiting elastic speed and the maximum speed before large-scale plastic deformation commences are computed. An indication is given of how similar methods may be used to analyze a rotating disk with no plane of symmetry perpendicular to the axis.

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