Fracture Modeling of Composite Materials: Fracture Modeling of Composite Materials
Program Organizers: Yan Li, Dartmouth College; Saurabh Puri, VulcanForms Inc
Monday 8:00 AM
February 24, 2020
Room: 10
Location: San Diego Convention Ctr
Session Chair: Yan Li, California State University, Long Beach; Travis Skinner, Arizona State University
8:00 AM Invited
An Integrated Computational and Experimental Framework to Understand the Competing Failure Mechanisms in Metal Matrix Composites: Yan Li1; Jun Cao2; Cyril Williams3; 1Thayer School of Engineering, Dartmouth College; 2California State University, Long Beach; 3US Army Research Laboratory
The development of high performance MMCs requires careful microstructure design which can improve fracture toughness while maintaining high strength. In metal matrix composite materials, reinforcement cracking and interface debonding are two competing failure mechanisms observed during the crack-reinforcements interactions. In this paper, we propose an integrated computational and experimental framework which elucidates the competing failure mechanisms by considering the effect of microstructure and loading conditions. The systematic studies focus on Al/SiC metal matrix composites. The cohesive parameters employed in the computational models are calibrated through Digital Image Correlation analysis.
8:30 AM
Computational Polyethylene-ceramic Composite Plate Design and Optimization: Trenin Bayless1; Jerome Downey1; Peter Lucon1; Scott Coguill1; 1Montana Technological University
A computational simulation utilizing ANSYS/AUTODYNE software is used as a guide for the production of an experimental composite structure capable of distributing ballistic impact energy with greater efficiency. The analysis is focused on a composite system with spaced tungsten carbide inserts woven into a polyethylene matrix. The structure is capable of absorbing of kinetic energy through both plastic deformation and the breaking of molecular bonds in the tungsten carbide. The tungsten carbide inserts provide both a high-density ceramic structure, and increase the surface area of the plastic deformation, thereby increasing the rate of energy absorption. The composite structure exhibits a greater weight-to-impact-resistance ratio than conventional designs. These structures are reliant on the variable geometry of the tungsten carbide insert structure and placement. Through analysis and design with complex geometries, the construction of lighter composite ballistic plates with the same functional protection as conventional ballistic plates becomes a scaleable possibility.
8:50 AM
A Reactive Molecular Dynamics Study on the Mechanical Properties of Alumina/Carbon Nanotube Composites: Yixin Su1; Yang Wang1; Narumasa Miyazaki1; Yusuke Ootani1; Nobuki Ozawa1; Momoji Kubo1; 1Tohoku University
Ceramics exhibit high stiffness and high-temperature stability, although brittleness limits their applications. Ceramic matrix composites (CMCs) with carbon nanotubes (CNTs) may provide a solution, yet previous experiments reported uncertainty in the reinforcement of CMCs with CNT. Consequently, the effect of variables such as annealing on reinforcement should be examined. In this research, the mechanical behavior of ceramic/CNT composites with and without annealing was investigated using reactive molecular dynamics methods. To reproduce CNTs at grain boundaries, amorphous alumina/CNT composites were considered. Without annealing, neither the Young’s modulus nor tensile strength changed with increasing CNT fraction. With annealing, both mechanical properties increased. Furthermore, the mechanical properties of the annealed models approach ideal predictions of composites, while those without annealing do not. The annealed models showed that CNT bore more atomic strain and showed less interfacial slippage between alumina and CNT. We assume that residual stress left by annealing contributes to this phenomenon.
9:10 AM Cancelled
Evaluation of Fracture Toughness of Cryogenically Treated High Nitrogen Martensitic Steel: Narendra Dhokey1; 1Government College of Engineering
A new class of High Nitrogen Martensitic steels (HNMS) is used in corrosive environment and at subzero temperatures. High hardness and low level of retained austenite in such steel is required for high stress applications like ball bearings of space crafts. In this report, HNMS steel was hardened (1075oC) followed by low temperature treatment at minus 80oC and then double tempering (500oC). Characterization was done by SEM microscopy, hardness measurement and fracture toughness testing in accordance with ASTM E1820. The combined effect of enhanced precipitation and tough tempered martensitic matrix has been discussed in light of mechanism on fracture toughness improvement. It was concluded that there was a threefold increase in fracture toughness of HNMS after a deep cryogenic treatment.
9:30 AM Break
10:00 AM Invited
Developing a Virtual Damage Sensor Using a Multiscale Coupled Electro-mechanical FE Model of a Piezoelectric Material: Somnath Ghosh1; Preetam Tarafder1; Saikat Dan1; 1Johns Hopkins University
This talk will develop a finite element model coupling transient electric and dynamic mechanical fields for piezoelectric materials. The mechanical field incorporates finite deformation kinematics with continuum damage relations to account for change in mechanical and piezoelectric material properties with deformation induced damage evolution. The coupled mechanical-piezoelectric model with damage will serve as a electric field-based virtual damage sensor. A coupled mechanical-piezoelectric (ME-PE) parametrically homogenized constitutive-damage model (PHCDM) will be developed for piezo-electric materials accounting for the microstructure and crack evolution in the microstructure. An electric field-based damage indicator function is proposed and calibrated from data obtained through numerical solutions using the ME-PE code. The function relates the electric field difference for undamaged and damaged conditions to the damage parameter, its rate and mechanical and piezoelectric material and damage properties. The virtual damage sensor will be used to examine damage conditions in stretchable piezoelectric conductors.
10:30 AM
An Improved Fracture Mechanics-informed Multiscale Thermomechanical Damage Model for Ceramic Matrix Composites: Travis Skinner1; Jacob Schichtel1; Aditi Chattopadhyay1; 1Arizona State University
A multiscale damage model is proposed to model the nonlinear mechanical behavior of silicon carbide (SiC) ceramic matrix composites (CMCs). The material stress-strain constitutive relationship will be derived using internal state variable (ISV) theory with a tensorial damage ISV, which will be defined to capture the effects of both micro- and macroscale matrix cracks initiating from manufacturing induced cavities, and a void nucleation ISV, which will capture the effects of void nucleation and coalescence due to grain boundary slipping and material diffusion. Fracture mechanics and crack growth kinetics will govern the progression of cracking and the temporal evolution of the damage ISV, while grain boundary slippage and material diffusion laws will govern the nucleation and coalescence of matrix voids. High temperature effects, which significantly affect CMC mechanical behavior, will be included in the thermomechanical formulations of the ISVs.
10:50 AM Cancelled
Micromechanical Analysis of Matrix Crack-induced Delamination in Cross-ply Laminates Under Tension: Chen Fu1; Xi Wang2; 1School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University,; 2School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University
A two-dimensional representative volume element model is developed to study the mechanism of matrix crack-induced delamination in cross-ply laminates under tension. Fiber-matrix debonding and matrix cracking were investigated in the 90°plies. The 0°plies were modeled as homogenized, anisotropic elastic solids. A special emphasis was put on the interlaminar region where the resin-rich area was included, and delamination was characterized by a plastic damage model of the matrix. Failure process and interactions of different damage mechanisms were accurately revealed by finite element analysis. A parametric study was done on different cross-ply laminates with various thickness of 90°ply to obtain the in-situ strength. The influence of thermal residual stress and voids on the mechanical response was also analyzed. Moreover, the proposed model can predict the initiation load of delamination and evaluate the effect of delamination on the homogenized longitudinal stiffness and transverse Poisson's responses of the laminates quantitatively.