scholarly journals A Fragile Points Method, with an interface debonding model, to simulate damage and fracture of U‐notched structures

2021 ◽  
Author(s):  
Kailei Wang ◽  
Baoying Shen ◽  
Mingjing Li ◽  
Leiting Dong ◽  
Satya N. Atluri
Keyword(s):  
Interface Debonding ◽  
Damage And Fracture

scholarly journals Effect of Stochastic Loading on Tensile Damage and Fracture of Fiber-Reinforced Ceramic-Matrix Composites

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2469 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Fiber Strength ◽  
Ceramic Matrix Composites ◽  
Tangent Modulus ◽  
Interface Debonding ◽  
Matrix Composites ◽  
Fiber Volume ◽  
Damage And Fracture ◽  
Stochastic Loading ◽  
Composite Strain ◽  
Tensile Damage

In this paper, the effect of stochastic loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated. A micromechanical constitutive model is developed considering multiple damage mechanisms under tensile loading. The relationship between stochastic stress, tangent modulus, interface debonding and fiber broken is established. The effects of the fiber volume, interface shear stress, interface debonding energy, saturation matrix crack spacing and fiber strength on tensile stress–strain curve, tangent modulus, interface debonding fraction and fiber broken fraction are analyzed. The experimental tensile damage and fracture of unidirectional and 2D SiC/SiC composites subjected to different stochastic loading stress are predicted. When fiber volume increases, the initial composite strain decreases, the initial tangent modulus increases, the transition stress for interface debonding decreases and the initial fiber broken fraction decreases. When fiber strength increases, the initial composite strain and fiber broken fraction decrease.

scholarly journals Experimental Investigation on Crack Behavior and Stress Thresholds of Sandstone Containing a Square Inclusion under Uniaxial Compression

2020 ◽  
Vol 10 (21) ◽  
pp. 7621
Author(s):  
Quanqi Zhu ◽  
Diyuan Li
Keyword(s):  
Uniaxial Compression ◽  
Shear Failure ◽  
Shear Crack ◽  
Image Correlation ◽  
Interface Debonding ◽  
Compression Tests ◽  
Strain Behavior ◽  
Damage And Fracture ◽  
Crack Behavior ◽  
Strength And Stiffness

To study the effect of strength, stiffness and inclination angle of square inclusions on failure characteristics of rock, uniaxial compression tests were carried out on prismatic sandstone containing a square hole with different filling modes and hole angles using a servo-hydraulic loading system. Digital image correlation and acoustic emission techniques were jointly applied to analyze the damage and fracture process, and the crack stress thresholds were determined qualitatively and quantitatively by combining the stress–strain behavior. The results show that the mechanical properties and crack stress thresholds of pre-holed specimens increase with the increase of the strength and stiffness of inclusions, and are affected by the hole angle. Rock failure is mainly caused by secondary crack propagation and shear crack coalescence, eventually forming mixed tensile-shear failure. The crack behavior, especially the crack initiation position, is affected by the filling mode and the hole angle. Interface debonding tends to initiate at the vertical interface, while interface slipping tends to propagate along the inclined interface. Under identical loading conditions, the specimen with 45° hole is more susceptible to crack and damage than that with 0° hole. Notably, inclusions can inhibit the hole deformation and the fracture of rock matrix, especially the sidewall spalling of 0° hole.

Comparison of prior exposure tensile damage and fracture of two-dimensional C/SiC and SiC/SiC fiber-reinforced ceramic-matrix composites

2020 ◽  
Vol 90 (23-24) ◽  
pp. 2782-2794
Author(s):  
Longbiao Li
Keyword(s):  
Tensile Strength ◽  
Fracture Strain ◽  
Prior Exposure ◽  
Interface Debonding ◽  
Fiber Volume ◽  
Damage And Fracture ◽  
Exposure Temperature ◽  
Fiber Characteristic ◽  
Sic Composites ◽  
Tensile Damage

In this paper, a micromechanical constitutive model for prior exposure tensile damage and fracture of fiber-reinforced ceramic-matrix composites is developed considering the multiple damage mechanisms of matrix multicracking, interface debonding and oxidation, and fiber fracture. The relationships between prior exposure temperature, duration time, interface debonding fraction, broken fiber fraction, tensile strength, and fracture strain of C/SiC and SiC/SiC composites are established. The experimental prior exposure tensile damage evolution and final fracture of two-dimensional (2D) C/SiC and SiC/SiC composites are predicted for different temperatures and duration times. The comparison analysis of prior exposure composite tensile strength, fracture strain, interface debonding fraction, and broken fiber fraction between 2D C/SiC and SiC/SiC composites is investigated. The effects of constituent properties and temperature on prior exposure tensile damage and fracture of 2D C/SiC and SiC/SiC composites are discussed. For 2D C/SiC and SiC/SiC composites under prior exposure at 1300℃, the fracture strain decreased with fiber volume, interface shear stress, and prior exposure temperature, and increased with fiber characteristic strength; the tensile strength increased with fiber volume and fiber characteristic strength, and decreased with prior exposure temperature; the interface debonding fraction decreased with fiber volume, and increased with prior exposure temperature; and the fiber broken fraction decreased with fiber volume and fiber characteristic strength, and increased with prior exposure temperature.

Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

1991 ◽  
Vol 49 ◽  
pp. 920-921
Author(s):  
K. B. Alexander ◽  
P. F. Becher
Keyword(s):  
Silicon Carbide ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Interface Debonding ◽  
Resolution Electron ◽  
Microstructural Evaluation ◽  
Carbon Coated ◽  
Electron Energy Loss ◽  
Interfacial Films ◽  
Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

scholarly journals Damage and fracture of biological and biomedical materials

2021 ◽  
Vol 241 ◽  
pp. 107067
Author(s):  
Vadim V. Silberschmidt ◽  
Jose Manuel Garcia Aznar
Keyword(s):  
Biomedical Materials ◽  
Damage And Fracture

scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

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