Parameter determination of constitutive relationship of 3004H24 aluminum alloy based on ductile damage model

Structures ◽  
2021 ◽  
Vol 34 ◽  
pp. 4447-4456
Author(s):  
Tao Wu ◽  
Ying Sun ◽  
Zhenggang Cao
Keyword(s):  
Aluminum Alloy ◽  
Damage Model ◽  
Constitutive Relationship ◽  
Ductile Damage ◽  
Parameter Determination ◽  
Relationship Of

Substrate-affected indentation contact parameters of elastoplastic coating/substrate composites

2009 ◽  
Vol 24 (3) ◽  
pp. 831-843 ◽  
Author(s):  
Mototsugu Sakai
Keyword(s):  
Finite Element ◽  
Strain Field ◽  
Constitutive Relationship ◽  
Contact Radius ◽  
Spatial Confinement ◽  
Composite Systems ◽  
Theoretical Predictions ◽  
Relationship Of ◽  
Contact Parameters

In coating/substrate bilayer systems, the indentation contact behavior transitionally varies from coatinglike to substratelike behaviors. Spatial confinement effects of the substrate induce very complicated plastic flows in the coating beneath the indenter, leading to a crucial difficulty that is not accounted for by any of the present quantitative analytical/theoretical predictions for the substrate-affected contact hardness. In this work, the author presents finite-element-based studies on the elastoplastic indentation contact mechanics of coating/substrate systems. The effect of the substrate is taken into account by introducing the spatially variable elastic modulus and the yield stress; this approach quantitatively describes the substrate-affected stress/strain field in the spatially localized area beneath the indenter. The elastoplastic constitutive relationship of the contact hardness for semi-infinite homogeneous bulks combined with these spatially variable material characteristics are successfully applied to analytically as well as quantitatively predict the substrate-affected contact hardness of bilayer composite systems having wide ranges of elastoplastic coating/substrate characteristics. The experimental procedures for determining the elastic/plastic parameters both of the coating and the substrate are also discussed, in which the importance of the experimental determination of substrate-affected indentation contact radius/area is emphasized.

On the Dependency of Ductile Damage Evolution to Stress State with Shock Loading Pre-Mechanical Working in 7075-T6 Aluminum Alloy

2016 ◽  
Vol 08 (04) ◽  
pp. 1650050 ◽  
Author(s):  
Sina Gohari Rad ◽  
Majid Alitavoli ◽  
Asghar Zajkani ◽  
Abolfazl Darvizeh
Keyword(s):  
Aluminum Alloy ◽  
Stress State ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Pressure Effects ◽  
Ductile Damage ◽  
Plastic Behavior ◽  
Special Focus ◽  
Mechanical Working

In this paper, the evolution of a ductile damage in the 7075-T6 aluminum alloy is considered based on stress state parameters with a special focus on pre-mechanical working dependency. Uniaxial stress–strain curves are investigated experimentally for two conditions; specimens with shock loaded pre-mechanical working and without it. This kind of loading is applied in order to find out impulsive pressure effects of damage variation procedure. Some experiments are done to take different stress states. Applying two fracture initiations criteria, i.e., Hosford–Coulomb and Xue models, two types of fracture locus of Al-7075-T6 are predicted in terms of plastic strains and stress state parameters under above conditions. By considering experimental data, a new ductile damage evolution model is proposed among plastic behavior. It is introduced by explicating an uncoupled plasticity and related to initial rate dependent stress state. By using both fracture models, our damage evolution model is implemented, phenomenologically as well as the Xue damage model, to compare results.

The Effect of Heterogeneity and Element Sizes on Rock Mechanics Properties

2011 ◽  
Vol 243-249 ◽  
pp. 2643-2646
Author(s):  
Hai Jun Lu ◽  
Guang Hua Cai ◽  
Li He ◽  
Zhu Yun Hu ◽  
Jiang Shan Li
Keyword(s):  
Numerical Simulation ◽  
Rock Mechanics ◽  
Rock Strength ◽  
Damage Model ◽  
Constitutive Relationship ◽  
Strain Relationship ◽  
Statistic Theory ◽  
Failure Models ◽  
Basic Characteristics ◽  
Relationship Of

Based on the analysis of the experiment, a statistical damage model can be established according with Weibull distribution from the basic characteristics of rocks, the statistic theory of heterogeneity and the microscopic principles of damages, analyze the constitutive relationship of rocks through the stress-strain relationship, heterogeneity, and the element sizes. According to the analysis of rock strength and failure models in numerical simulation, it is acquired the influence of heterogeneity and element sizes on rock mechanics properties. The results of numerical simulation provide a new way for the study of the medium macro behavior on the deformations and fractures.

Study on the Simulation of Damage Constitutive Relationship for High Strength and High Performance Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 636-639
Author(s):  
Shan Suo Zheng ◽  
Yi Hu ◽  
Bin Liu ◽  
Ming Xie ◽  
Qing Lin Tao
Keyword(s):  
Constitutive Equation ◽  
High Performance ◽  
High Performance Concrete ◽  
Mechanical Test ◽  
Damage Model ◽  
High Strength ◽  
Constitutive Relationship ◽  
Two Parameters ◽  
Relationship Of ◽  
Stochastic Damage

The damage evolution laws of high strength and high performance concrete (HSHPC) are obtained by a large number of experiments on mechanical properties. Based on stochastic damage model, a new damage variable with two parameters is proposed to describe the damage constitutive relationship of HSHPC and the damage constitutive equation is established by boundary conditions. Compared mechanical test result of HSHPC with theoretical calculation, it is shown that the damage constitutive equation can reflect the damage characteristics of HSHPC reasonably. The research identifies a certain theoretical basis for further studying on dynamic and stochastic damage constitutive relationship of HSHPC.

STEM and ELS Observation of Early Oxide Formation on the Surface of Cr Thin Films

1980 ◽  
Vol 38 ◽  
pp. 412-413
Author(s):  
Fumio Watari ◽  
J. M. Cowley
Keyword(s):  
Thin Films ◽  
Optical System ◽  
Room Temperature ◽  
Oxide Formation ◽  
Initial Nucleation ◽  
Diffraction Patterns ◽  
Relationship Of ◽  
Multiple Twinning ◽  
Moderately High Temperature

STEM coupled with the optical system was used for the investigation of the early oxidation on the surface of Cr. Cr thin films (30 – 1000Å) were prepared by evaporation onto the polished or air-cleaved NaCl substrates at room temperature and 45°C in a vacuum of 10−6 Torr with an evaporation speed 0.3Å/sec. Rather thick specimens (200 – 1000Å) with various preferred orientations were used for the investigation of the oxidation at moderately high temperature (600 − 1100°C). Selected area diffraction patterns in these specimens are usually very much complicated by the existence of the different kinds of oxides and their multiple twinning. The determination of the epitaxial orientation relationship of the oxides formed on the Cr surface was made possible by intensive use of the optical system and microdiffraction techniques. Prior to the formation of the known rhombohedral Cr2O3, a thin spinel oxide, probably analogous to γ -Al203 or γ -Fe203, was formed. Fig. 1a shows the distinct epitaxial growth of the spinel (001) as well as the rhombohedral (125) on the well-oriented Cr(001) surface. In the case of the Cr specimen with the (001) preferred orientation (Fig. 1b), the rings explainable by spinel structure appeared as well as the well defined epitaxial spots of the spinel (001). The microdif fraction from 20A areas (Fig. 2a) clearly shows the same pattern as Fig. Ia with the weaker oxide spots among the more intense Cr spots, indicating that the thickness of the oxide is much less than that of Cr. The rhombohedral Cr2O3 was nucleated preferably at the Cr(011) sites provided by the polycrystalline nature of the present specimens with the relation Cr2O3 (001)//Cr(011), and by further oxidation it grew into full coverage of the rest of the Cr surface with the orientation determined by the initial nucleation.

Sign in / Sign up

Export Citation Format

Share Document