The Effect of Matrix Constitutive Model on Residual Thermal Stresses in MMC

1994 ◽  
Vol 116 (4) ◽  
pp. 505-511 ◽  
Author(s):  
James B. Brayshaw ◽  
Marek-Jerzy Pindera
Keyword(s):  
Thermal Stresses ◽  
Constitutive Models ◽  
Thermomechanical Analysis ◽  
Creep Model ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Constitutive Theories ◽  
The Matrix ◽  
Incremental Formulation ◽  
Power Law Creep

A thermomechanical analysis of advanced composites in a wide temperature range is presented. This analysis is based on the micromechanics method of cells. An incremental formulation of the micromechanics model is developed to facilitate the use of various inelastic constitutive theories. These theories incorporate time-dependent and temperature-dependent features for modeling different types of metal matrices. The constitutive models include the Bodner-Partom unified theory of viscoplasticity, the incremental plasticity model, and a power-law creep model. The effect of the cooling rate, taking into account temperature-dependent matrix properties, on residual thermal stresses is subsequently investigated for a SiC/Ti composite using the different models for the matrix phases. Predictions generated using the micromechanics method are compared with available results of finite-element analysis.

Finite Element Simulation for Creep Response of Strengthened Wood/PVC Composite

2013 ◽  
Vol 747 ◽  
pp. 261-264 ◽  
Author(s):  
T. Pulngern ◽  
K. Preecha ◽  
Narongrit Sombatsompop ◽  
V. Rosarpitak
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Power Law ◽  
High Carbon Steel ◽  
Creep Model ◽  
Element Analysis ◽  
Creep Response ◽  
Element Simulation ◽  
Before And After ◽  
Power Law Creep

This paper investigates the finite element simulation to predict the creep response of Wood/PVC (WPVC) composite members before and after strengthening by using high carbon steel (HCS) flat bar strip adhered to the tension side. The creep parameters based on power law models of WPVC composites and the HCS flat bars were determined experimentally. Then, the nonlinear finite element analysis (FEA) software of ABAQUS was applied to predict the creep behaviors of composite members using the obtained experimentally creep parameters of individual component of WPVC composites and HCS flat bars. Good correlation between finite element simulation and experimental results are obtained for all cases. ABAQUS software with power law creep model show good potential for prediction the creep response of WPVC composites before and after strengthening.

Overall Temperature-Dependent Elastic Properties of Carbon Fiber Polymer Matrix Composites at High Temperatures

2020 ◽  
Author(s):  
Teja G. K. Konduri ◽  
Olesya I. Zhupanska
Keyword(s):  
Carbon Fiber ◽  
Elastic Properties ◽  
Polymer Matrix ◽  
Volume Fraction ◽  
Polymer Matrix Composites ◽  
Type Equation ◽  
Temperature Dependent ◽  
Element Analysis ◽  
The Matrix ◽  
Pyrolysis Gases

Abstract In this paper we discuss the effect of volumetric ablation on the overall elastic properties of the carbon fiber reinforced polymer matrix composite. An Arrhenius type equation describing polymer decomposition was used to determine volume fractions of evolving polymer matrix phases (i.e. polymer, growing pores filled with pyrolysis gases, and char). The effect of the pressure exerted by pyrolysis gases trapped inside the pores was analyzed. Microstructures consisting of carbon fibers (circular inclusions) in the matrix and pores (elliptic inclusions) in the polymer were generated. Temperature dependency was addressed by generating microstructures with different volume fraction of pores, which were calculated from the mass loss model. Two-step numerical homogenization of representative volume elements (RVEs) was performed using finite element analysis (FEA). The developed procedures were applied to calculate temperature dependent (up to 700 K) effective elastic properties of the AS4/3501-6 composite. The results are compared to the existing experimental data and show good agreement.

A New Creep Constitutive Model for Eutectic Solder Alloy

2002 ◽  
Vol 124 (2) ◽  
pp. 85-90 ◽  
Author(s):  
X. Q. Shi ◽  
Z. P. Wang ◽  
W. Zhou ◽  
H. L. J. Pang ◽  
Q. J. Yang
Keyword(s):  
Constitutive Model ◽  
Testing Temperature ◽  
Creep Model ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Creep Flow ◽  
Reliability Of Solder Joints ◽  
Power Law Creep ◽  
Creep Constitutive Model

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to be capable of explaining the issues of stress and temperature dependent stress exponent and activation energy in the Arrhenius power-law creep model. Furthermore, the model was employed to predict accurately the long-term reliability of solder joints in a PBGA assembly.

Nonlinear Viscoelastic Finite Element Analysis of Physical Aging in an Encapsulated Transformer

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
M. A. Neidigk ◽  
Y.-L. Shen
Keyword(s):  
Thermal Stresses ◽  
Physical Aging ◽  
Constitutive Models ◽  
Thermomechanical Properties ◽  
Voltage Transformer ◽  
Element Analysis ◽  
Actual Performance ◽  
Nonlinear Viscoelastic ◽  
High Voltage Transformer ◽  
Thermal Cooling

The generation of thermal stresses is a major cause for mechanical failure in encapsulated electronic components. In this study numerical modeling is employed to analyze thermal stresses in a high-voltage transformer encapsulated with filled epoxy. The transformer assembly consists of materials with an extremely disparate range of thermomechanical properties. The thermal histories considered mimic those in the operational condition. It is found that, upon thermal cooling from elevated temperature, the ceramic core can be under local tensile stress although it is entirely surrounded by materials with much greater coefficients of thermal expansion. The unique aspect of this paper originates from the fact that the volume shrinkage of the viscoelastic encapsulant during physical aging contributes to an increase in stress over time, thus increasing the tendency of fracture. This counter intuitive result (stress increase due to nonlinear viscoelastic physical aging) can now be predicted using constitutive models recently developed at Sandia National Laboratories. When a silicone coating between the core and the encapsulation is included, the stress is significantly reduced. The modeling result is shown to corroborate with the actual performance of the transformer.

Different Conservation Laws Constructed on Warpage Analyses for Bimaterial Plates With Temperature-Dependent Properties

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Chih-Sung Chen
Keyword(s):  
Conservation Laws ◽  
Polymeric Material ◽  
Residual Strain ◽  
Conservation Law ◽  
Constitutive Models ◽  
Thermomechanical Analysis ◽  
Large Error ◽  
Temperature Dependent ◽  
Time Saving ◽  
Strain Stress

Polymeric material has been applied in electronic product extensively, especially for packaging applications, thus thermomechanical analyses for encapsulated structure are frequently encountered. However, modulus and thermally induced strain of polymeric material are not constant, but time- and temperature-dependence. For simplification of the stress constitutive models, particularly for applications on electronic packaging can be found in literature, the time-dependent behavior could be neglected. Otherwise, the property only considered as a function of temperature can achieve time saving and cost down, but to the best of the author’s knowledge, the thermomechanical analysis based on different conservation laws so far has not been studied indeed. Most of the relative studies published in literature are in strain conservation law, and recently strain–stress conservation law was formulated, so-called force-displacement incremental solution. This study has developed a stress-based conservation law regardless of derived strain and strain–stress based conservation laws for stress constitutive models applied in thermomechanical analysis; meanwhile, incorporated cross-link induced residual strain from polymer forming. Furthermore, the nonincrement approach is implemented by a concept of force and moment equilibrium on the flexural stiffness of final stage, and derived for efficiency enhancing. On the other hand, analytical solutions based on different conservation laws for bimaterial plate were utilized to compare with experimental measurements. The results indicate that warpage analysis based on stress conservation law with temperature-dependent property can be more realistically predicted over a range of temperature, whereas a large error can be caused by using approximated CTE or nonconsidering residual strain, especially for temperature above Tg.

Viscoplastic Constitutive Properties and Reliability of Lead-Free Sn3.9Ag0.6Cu Solder

2003 ◽  
Author(s):  
Qian Zhang ◽  
Abhijit Dasgupta ◽  
Peter Haswell
Keyword(s):  
Steady State ◽  
Constitutive Models ◽  
Constant Load ◽  
Mechanical Tests ◽  
Test System ◽  
Steady State Creep ◽  
Lead Free ◽  
Creep Model ◽  
Element Analysis ◽  
Constitutive Properties

The viscoplastic constitutive properties of Sn3.9Ag0.6Cu lead-free alloy are presented and compared with baseline data from eutectic Sn63Pb37 solder. Steady-state creep models are obtained from creep and monotonic tests at three different temperatures for both solders. Based on steady-state creep results and creep test data, a transient creep model is developed for both Pb-free and Sb37Pb solders. One-dimensional incremental model of the test setup is developed to simulate constant-load creep, monotonic, and isothermal cyclic mechanical tests performed over various temperatures, strain rates and stresses using a thermo-mechanical-microstructural (TMM) test system, developed by the authors. By fitting simulation results to monotonic testing data, plastic models are also achieved. The devoloped viscoplastic constitutive models are evaluated in a two-dimensional nonlinear Finite element analysis of a PBGA352 package under a −55°C∼125°C thermal cycling environment. The viscoplastic behavior of Pb-free solder is compared with that of eutectic Sn37Pb solder.

Creep Crack Growth of P92 Welds

2008 ◽  
Author(s):  
Masataka Yatomi ◽  
Akio Fuji ◽  
Ken-ichi I. Kobayashi ◽  
Masaaki Tabuchi ◽  
Takeo Yokobori ◽  
...  
Keyword(s):  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Creep Model ◽  
Element Analysis ◽  
Creep Properties ◽  
Creep Crack ◽  
Type Iv ◽  
Growth Properties ◽  
Power Law Creep

This paper represents creep properties and creep crack growth properties for P92 welds. The CCG tests were carried out using cross-welded compact tension (C (T) specimens at several temperatures. The crack front was located at HAZ region to simulate Type IV crack. Finite element analysis was conducted to simulate multiaxiality in welded joints and compare the experimental results. The constitutive behaviour for these materials is described by a power law creep model.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 39 (1) ◽  
pp. 189-199
Author(s):  
Longbiao Li
Keyword(s):  
Strain Energy ◽  
Ceramic Matrix Composites ◽  
Critical Value ◽  
Matrix Cracking ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Temperature Dependent ◽  
Damage State ◽  
The Matrix ◽  
Sic Composites

AbstractIn this paper, the temperature-dependent matrix multicracking evolution of carbon-fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) is investigated. The temperature-dependent composite microstress field is obtained by combining the shear-lag model and temperature-dependent material properties and damage models. The critical matrix strain energy criterion assumes that the strain energy in the matrix has a critical value. With increasing applied stress, when the matrix strain energy is higher than the critical value, more matrix cracks and interface debonding occur to dissipate the additional energy. Based on the composite damage state, the temperature-dependent matrix strain energy and its critical value are obtained. The relationships among applied stress, matrix cracking state, interface damage state, and environmental temperature are established. The effects of interfacial properties, material properties, and environmental temperature on temperature-dependent matrix multiple fracture evolution of C/SiC composites are analyzed. The experimental evolution of matrix multiple fracture and fraction of the interface debonding of C/SiC composites at elevated temperatures are predicted. When the interface shear stress increases, the debonding resistance at the interface increases, leading to the decrease of the debonding fraction at the interface, and the stress transfer capacity between the fiber and the matrix increases, leading to the higher first matrix cracking stress, saturation matrix cracking stress, and saturation matrix cracking density.

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