Micromechanical Modeling for the Damage Accumulation and Adhesive Wear of Metallic Materials Containing Inclusions

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Aizhong Wu ◽  
Lin Weng ◽  
Dingyu Hu ◽  
Aihua Liao
Keyword(s):  
Adhesive Wear ◽  
Shear Fracture ◽  
Micromechanical Model ◽  
Micromechanical Modeling ◽  
Metallic Materials ◽  
Contact Loading ◽  
Micro Cracks ◽  
Proposed Model ◽  
The Matrix ◽  
Model Crack

Abstract Metallic materials usually contain some amounts of inclusions which are known to affect their mechanical properties since the bonding strength of the matrix–inclusion interface is relatively low, voids or cracks are thus easily formed under a tensile loading. However, under a contact loading, the effects of subsurface inclusions on the sliding wear of metallic materials are not thoroughly understood. In this work, a micromechanical model is proposed to study the shear fracture and wear of metallic materials containing random inclusions. With the model, crack branching and crack aggregation during contact loading are simulated, and the formation process of sheet-like wear particles is clarified. It is demonstrated that the subsurface micro-cracks, particularly those near inclusions, and their subsequent evolution play a major role in the adhesive wear. This investigation is helpful in understanding the adhesive mechanism of wear, and the proposed model could be a promising approach for the prediction of adhesive wear.

Multicoating Inhomogeneities Problem for Effective Viscoelastic Properties of Particulate Composite Materials

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Yao Koutsawa ◽  
Mohammed Cherkaoui ◽  
El Mostafa Daya
Keyword(s):  
Loss Modulus ◽  
Micromechanical Model ◽  
Polymer System ◽  
High Capacity ◽  
Viscoelastic Behavior ◽  
Particulate Composite ◽  
Micromechanical Modeling ◽  
High Loss ◽  
Wide Range ◽  
The Matrix

The present work extends the multicoated micromechanical model of Lipinski et al. (2006, “Micromechanical Modeling of an Arbitrary Ellipsoidal Multi-Coated Inclusion,” Philos. Mag., 86(10), pp. 1305–1326) in the quasistatic domain to compute the effective material moduli of a viscoelastic material containing multicoated spherical inclusions displaying elastic or viscoelastic behavior. Losses are taken into account by introducing the frequency-dependent complex stiffness tensors of the viscoelastic matrix and the multicoated inclusions. The advantage of the micromechanical model is that it is applicable to the case of nonspherical multicoated inclusions embedded in anisotropic materials. The numerical simulations indicate that with proper choice of material properties, it is possible to engineer multiphase polymer system to have a high-loss modulus (good energy dissipation characteristics) for a wide range of frequencies without substantially degrading the stiffness of the composite (storage modulus). The numerical analyses show also that with respect to the relative magnitudes of the loss factors and the storage moduli of the matrix, inclusion and coating, the overall properties of the viscoelastic particulate composite are dominated by the properties of the matrices in some frequency ranges. The model can thus be a suitable tool to explore a wide range of microstructures for the design of materials with high capacity to absorb acoustic and vibrational energies.

Micromechanical Modeling of Viscoplastic Behavior of Laminated Polymer Composites With Thermal Residual Stress Effect

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Qiang Chen ◽  
Xuefeng Chen ◽  
Zhi Zhai ◽  
Xiaojun Zhu ◽  
Zhibo Yang
Keyword(s):  
Residual Stress ◽  
Polymer Matrix Composites ◽  
Micromechanical Model ◽  
Thermal Residual Stress ◽  
Micromechanical Modeling ◽  
Multiscale Approach ◽  
Stress Effect ◽  
Accurate Analysis ◽  
Rate Dependent ◽  
Residual Stress Effect

In this paper, a multiscale approach has been developed for investigating the rate-dependent viscoplastic behavior of polymer matrix composites (PMCs) with thermal residual stress effect. The finite-volume direct averaging micromechanics (FVDAM), which effectively predicts nonlinear response of unidirectional fiber reinforced composites, is incorporated with improved Bodner–Partom model to describe the viscoplastic behavior of PMCs. The new micromechanical model is then implemented into the classical laminate theory, enabling efficient and accurate analysis of multidirectional PMCs. The proposed multiscale theory not only predicts effective thermomechanical viscoplastic response of PMCs but also provides local fluctuations of fields within composite microstructures. The deformation behaviors of several unidirectional and multidirectional PMCs with various fiber configurations are extensively simulated at different strain rates, which show a good agreement with the experimental data found from the literature. Influence of thermal residual stress on the viscoplastic behavior of PMCs is closely related to fiber orientation. In addition, the thermal residual stress effect cannot be neglected in order to accurately describe the rate-dependent viscoplastic behavior of PMCs.

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

An analytical model for predicting the shear strength of unsaturated soils

2022 ◽  
pp. 1-57
Author(s):  
Tuan A. Pham ◽  
Melis Sutman
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Unsaturated Soils ◽  
High Performance ◽  
Micromechanical Model ◽  
Experimental Studies ◽  
Stress Equilibrium ◽  
Proposed Model ◽  
New Equation ◽  
Multi Phase

The prediction of shear strength for unsaturated soils remains to be a significant challenge due to their complex multi-phase nature. In this paper, a review of prior experimental studies is firstly carried out to present important pieces of evidence, limitations, and some design considerations. Next, an overview of the existing shear strength equations is summarized with a brief discussion. Then, a micromechanical model with stress equilibrium conditions and multi-phase interaction considerations is presented to provide a new equation for predicting the shear strength of unsaturated soils. The validity of the proposed model is examined for several published shear strength data of different soil types. It is observed that the shear strength predicted by the analytical model is in good agreement with the experimental data, and get high performance compared to the existing models. The evaluation of the outcomes with two criteria, using average relative error and the normalized sum of squared error, proved the effectiveness and validity of the proposed equation. Using the proposed equation, the nonlinear relationship between shear strength, saturation degree, volumetric water content, and matric suction are observed.

scholarly journals Effect of Porosity on Mechanical Properties of 3D Printed Polymers: Experiments and Micromechanical Modeling Based on X-Ray Computed Tomography Analysis

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1154 ◽  
Author(s):  
Wang ◽  
Zhao ◽  
Fuh ◽  
Lee
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Fused Deposition Modeling ◽  
Micromechanical Model ◽  
Micromechanical Modeling ◽  
X Ray ◽  
Fused Deposition ◽  
3D Printed ◽  
X Ray Computed

Additive manufacturing (commonly known as 3D printing) is defined as a family of technologies that deposit and consolidate materials to create a 3D object as opposed to subtractive manufacturing methodologies. Fused deposition modeling (FDM), one of the most popular additive manufacturing techniques, has demonstrated extensive applications in various industries such as medical prosthetics, automotive, and aeronautics. As a thermal process, FDM may introduce internal voids and pores into the fabricated thermoplastics, giving rise to potential reduction on the mechanical properties. This paper aims to investigate the effects of the microscopic pores on the mechanical properties of material fabricated by the FDM process via experiments and micromechanical modeling. More specifically, the three-dimensional microscopic details of the internal pores, such as size, shape, density, and spatial location were quantitatively characterized by X-ray computed tomography (XCT) and, subsequently, experiments were conducted to characterize the mechanical properties of the material. Based on the microscopic details of the pores characterized by XCT, a micromechanical model was proposed to predict the mechanical properties of the material as a function of the porosity (ratio of total volume of the pores over total volume of the material). The prediction results of the mechanical properties were found to be in agreement with the experimental data as well as the existing works. The proposed micromechanical model allows the future designers to predict the elastic properties of the 3D printed material based on the porosity from XCT results. This provides a possibility of saving the experimental cost on destructive testing.

scholarly journals Development of High-Performance SiCp/Al-Si Composites by Equal Channel Angular Pressing

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 738 ◽  
Author(s):  
Qiong Xu ◽  
Aibin Ma ◽  
Junjie Wang ◽  
Jiapeng Sun ◽  
Jinghua Jiang ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Equal Channel Angular Pressing ◽  
High Performance ◽  
Adhesive Wear ◽  
Processing Route ◽  
Matrix Composites ◽  
New Approach ◽  
Angular Pressing ◽  
The Matrix ◽  
Industry Applications

Relatively low compactness and unsatisfactory uniformity of reinforced particles severely restrict the performance and widespread industry applications of the powder metallurgy (PM) metal matrix composites (MMCs). Here, we developed a combined processing route of PM and equal channel angular pressing (ECAP) to enhance the mechanical properties and wear resistance of the SiCp/Al-Si composite. The results indicate that ECAP significantly refined the matrix grains, eliminated pores and promoted the uniformity of the reinforcement particles. After 8p-ECAP, the SiCp/Al-Si composite consisted of ultrafine Al matrix grains (600 nm) modified by uniformly-dispersed Si and SiCp particles, and the composite relative density approached 100%. The hardness and wear resistance of the 8p-ECAP SiCp/Al-Si composite were markedly improved compared to the PM composite. More ECAP passes continued a trend of improvement for the wear resistance and hardness. Moreover, while abrasion and delamination dominated the wear of PM composites, less severe adhesive wear and fatigue mechanisms played more important roles in the wear of PM-ECAP composites. This study demonstrates a new approach to designing wear-resistant Al-MMCs and is readily applicable to other Al-MMCs.

Mechanics of the Segmentation of an Embedded Fiber, Part I: Experimental Investigations

1995 ◽  
Vol 62 (1) ◽  
pp. 87-97 ◽  
Author(s):  
A. ten Busschen ◽  
A. P. S. Selvadurai
Keyword(s):  
Structural Parameters ◽  
Matrix Material ◽  
Micromechanical Modeling ◽  
Experimental Investigations ◽  
Shear Stresses ◽  
Research Attention ◽  
Fragmentation Test ◽  
The Matrix ◽  
Matrix Region ◽  
Interface Bond

Micromechanical modeling is an important aspect in the study of fiber-reinforced composites. In such studies, an important class of structural parameters is formed by the interaction between the matrix and the embedded fibers. These interactive processes can be investigated by an appeal to a test which involves the segmentation of an embedded fiber. This test is referred to as a “fragmentation test.” During a fragmentation test, two distinct fracture phenomena are observed. These phenomena are directly related to the integrity of bond between the embedded fiber and the matrix. The first phenomenon involves situations where the interface bond is weaker than the matrix material. In this case the fiber fragment ends will slip and in this region shear stresses are transmitted by friction and/or interlocking mechanical actions. In contrast, when the interface bond has stronger properties than the matrix material, cracking will occur in the matrix region. Here, a crack initiated in the fiber will propagate into the matrix region typically forming conoidal cracks, or combinations of conoidal and flat cracks. This paper describes the background of the fragmentation test and the associated experimental research. Attention is focused on the experimental evaluation of matrix fracture topographies encountered in the fragmentation test.

In-plane shear of nanoprepreg/nanostitched three-dimensional carbon/epoxy multiwalled carbon nanotubes composites

2019 ◽  
Vol 53 (24) ◽  
pp. 3413-3431 ◽  
Author(s):  
Kadir Bilisik ◽  
Nesrin Karaduman ◽  
Gulhan Erdogan ◽  
Erdal Sapanci ◽  
Sila Gungor
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Shear Fracture ◽  
Three Dimensional ◽  
Carbon Fabric ◽  
Multiwalled Carbon ◽  
Plane Shear ◽  
The Matrix ◽  
Delamination Area ◽  
Base Structure

The in-plane shear properties of nanostitched three-dimensional (3D) carbon/epoxy composites were investigated. Adding the stitching fiber or multiwalled carbon nanotubes or nanostitched fiber into carbon fabric preform slightly improved the shear strength and modulus of stitched and stitched nanocomposites. The in-plane shear fracture of the base and nanostructures was extensive delamination and tensile fiber failures in the sheared region. But, the stitched and stitched nanocomposites had angular deformation of the stitching yarns in the fiber scissoring areas, shear hackles in the matrix and successive fiber breakages in the interlayers. Probably, this mechanism prohibited extensive interlayer opening in the nanostitched composites. The results exhibited that introducing the stitching fiber (1.44%) and multiwalled carbon nanotubes (0.03125%) in the base structure enhanced its transverse fracture properties as a form of confined delamination area. Therefore, the damaged tolerance properties of the stitched nanocomposites were enhanced.

Micromechanics-based analyses of short fiber-reinforced composites with functionally graded interphases

2019 ◽  
Vol 54 (8) ◽  
pp. 1031-1048 ◽  
Author(s):  
Yang Yang ◽  
Qi He ◽  
Hong-Liang Dai ◽  
Jian Pang ◽  
Liang Yang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Elastic Properties ◽  
Effective Properties ◽  
Micromechanical Model ◽  
Short Fiber ◽  
Functionally Graded ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
The Matrix

A micromechanical model for short fiber-reinforced composites (SFRCs) with functionally graded interphases and a systematic prediction scheme to determine the effective properties are presented. The matrix and the fibers are regarded to be linear elastic, isotropic, and homogeneous. Fibers are assumed to be ellipsoids coated perfectly by functionally graded interphases, which is supposed to be formed chemically or physically by the constituents near the interface. First, to analyze the grading interphase effect, layer-wise concept is followed to divide the functionally graded interphases into multi-homogeneous sub-layers. Next, to take the effect of functionally graded interphases into account, a combination of multi-inclusion method and Mori–Tanaka method is applied to predict effective elastic properties of this unidirectional SFRCs with respect to the content and aspect ratio of the inclusions. By employing coordinate transformation, spatially elastic moduli are obtained. Finally, Voigt homogenization scheme is used to obtain the overall, averaged, symmetrical elastic properties of the SFRCs. Numerical examples and analyses demonstrate the applicability of the proposed method and indicate the influences of graded interphase, orientation, and aspect ratio of inclusions as well as properties and contents of the constituents on the overall properties of SFRCs.

Brittle-Ductile Transition in Heterogeneous Metallic Materials [PowerPoint Submission]

2006 ◽  
Vol 978 ◽  
Author(s):  
Silvester John Noronha ◽  
Nasr M Ghoniem
Keyword(s):  
Fracture Toughness ◽  
Tensile Stress ◽  
Size Distribution ◽  
Crack Tip ◽  
Transition Curve ◽  
Crack Plane ◽  
Metallic Materials ◽  
Brittle Ductile Transition ◽  
Discrete Dislocation ◽  
The Matrix

AbstractWe present a model for the brittle - ductile transition in heterogenous metallic materials based on two dimensional discrete dislocation simulations of crack-tip plasticity. The sum of elastic fields of the crack and the emitted dislocations defines an elasto-plastic crack field. Effects of crack-tip blunting of the macrocrack are included in the simulations. The plastic zone characteristics are found to be in agreement with continuum models, with the added advantage that the hardening behavior comes out naturally in our model. The present model is composed of a macrocrack with microcracks ahead of its tip. These microcracks represent potential fracture sites at internal inhomogenities, such as brittle precipitates. Dislocations that are emitted from the crack-tip account for plasticity. When the tensile stress at the microcrack situated along the crack plane attains a critical value over a distance fracture is assumed to take place. The brittle-ductile transition curve is obtained by determining the fracture toughness at various temperatures. Factors that contribute to the sharp upturn in fracture toughness with temperature are found to be: the decrease in tensile stress ahead of the crack tip due to increase in blunting, and the increase in dislocation mobility. The inherent scatter in fracture toughness measurements are studied by using a size distribution for microcracks, distributed on the crack plane of the macrocrack. The scatter in fracture toughness measurements is found to be an effect of the size distribution of microcracks rather than their spatial distribution on the matrix ahead of the crack plane. When compared, the obtained results are in agreement with the existing experimental data.

Sign in / Sign up

Export Citation Format

Share Document