Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 13 of 13
Full-Text Articles in Mechanical Engineering
Fracture Parameters For Natural Rubber Under Dynamic Loading, Michelle Hoo Fatt, L. Chen, A. Al-Quraishi
Fracture Parameters For Natural Rubber Under Dynamic Loading, Michelle Hoo Fatt, L. Chen, A. Al-Quraishi
Dr. Michelle S. Hoo Fatt
Abstract: An experimental study was conducted to evaluate the tear energy of unfilled and 25 phr carbon black-filled natural rubber with varying loading rates. The variation of the tear energy with far-field sample strain rate between 0.01 to 10 s−1 was found to be different from tensile strip and pure shear specimens. Above a sample strain rate of 10 s−1, the tear energy calculated from either specimen was comparable. The differences in the tear energy derived from the tensile strip and pure shear specimens were attributed to differences in the local crack tip stress state and strengthening of the material …
Local Facesheet Pulse Buckling In A Curved, Composite Sandwich Panel, Yifei Gao, Michelle Hoo Fatt
Local Facesheet Pulse Buckling In A Curved, Composite Sandwich Panel, Yifei Gao, Michelle Hoo Fatt
Dr. Michelle S. Hoo Fatt
Local facesheet buckling of a curved sandwich panel subjected to external pressure pulse loading was investigated in this paper. Equations of motion for the facesheet transient deformations in the sandwich shell were derived from Lagrange’s equations of motion, and solutions using this approach compared well with FEA results from ABAQUS Standard. Both facesheet fracture during stable deformation response and local dynamic pulse buckling of facesheets were considered as possible modes of failure in the curved sandwich panel. Parametric studies indicated that local facesheets buckling is more likely to occur than facesheet fracture in thin and deep curved sandwich panels. The …
Dynamic Pulse Buckling Of Single Curvature Composite Shells Under External Blast, Yifei Gao, Michelle Hoo Fatt
Dynamic Pulse Buckling Of Single Curvature Composite Shells Under External Blast, Yifei Gao, Michelle Hoo Fatt
Dr. Michelle S. Hoo Fatt
Dynamic pulse buckling of a single curvature composite shell under external pressure was examined using Lagrange's equation of motion and the Budiansky–Roth criterion. The predicted transient shell response compared very well with results from ABAQUS Implicit, and the predicted buckling loads also agreed with experiments on steel arches. Load duration determined whether the buckling was impulsive, dynamic or quasi-dynamic. Thicker composite shells were more likely to fail by first-ply failure rather than buckling. It was shown that the composite lay-up could be adjusted to increase the buckling resistance of the shell.
A Constitutive Equation For Filled Rubber Under Cyclic Loading, Min Liu, Michelle Hoo Fatt
A Constitutive Equation For Filled Rubber Under Cyclic Loading, Min Liu, Michelle Hoo Fatt
Dr. Michelle S. Hoo Fatt
This paper describes experiments and the development of constitutive equations to predict the steady-state response of filled rubber under cyclic loading. An MTS servo-hydraulic machine was used to obtain the dynamic hysteresis curves for a filled rubber compound in uniaxial tension-compression. The material tests were performed with mean strains from −0.1 to 0.1, strain amplitudes ranging from 0.02 to 0.1, and strain rates between 0.01 and 10 s−1. Temporary material set, the Payne effect and rate-dependence were observed from the experimental results. A hyper-viscoelastic constitutive model was developed to characterize the dynamic response of the rubber. A cornerstone …
Dynamic Pulse Buckling Of Composite Shells Subjected To External Blast, Michelle Hoo Fatt, Sunil Pothula
Dynamic Pulse Buckling Of Composite Shells Subjected To External Blast, Michelle Hoo Fatt, Sunil Pothula
Dr. Michelle S. Hoo Fatt
Dynamic pulse buckling of woven E-Glass/Vinyl Ester and laminated E-Glass/Epoxy cylindrical shells subjected to uniform overpressure and asymmetric pressure pulse (side-on explosion) were examined. The solutions for the radial shell deformations were represented by Mathieu differential equations. The dynamic instability of the shells was determined from a Mathieu stability diagram. It was found that the stability of the shells depended on lay-up, aspect ratio as well as impulse distribution. The stable vibration response of the shells with side-on explosion compared well with finite element solutions using a Dynamic, Implicit analysis in ABAQUS Standard. First-ply failure of the woven E-Glass/Vinyl Ester …
A Wave Propagation Model For The High Velocity Impact Response Of A Composite Sandwich Panel, Michelle Hoo Fatt, Dushyanth Sirivolu
A Wave Propagation Model For The High Velocity Impact Response Of A Composite Sandwich Panel, Michelle Hoo Fatt, Dushyanth Sirivolu
Dr. Michelle S. Hoo Fatt
A solution methodology to predict the residual velocity of a hemispherical-nose cylindrical projectile impacting a composite sandwich panel at high velocity is presented. The term high velocity impact is used to describe impact scenarios where the projectile perforates the panel and exits with a residual velocity. The solution is derived from a wave propagation model involving deformation and failure of facesheets, through-thickness propagation of shock waves in the core, and through-thickness core shear failure. Equations of motion for the projectile and effective masses of the facesheets and core as the shock waves travel through sandwich panel are derived using Lagrangian …
Analytical Modeling Of Composite Sandwich Panels Under Blast Loads, Michelle Hoo Fatt, Leelaprasad Palla
Analytical Modeling Of Composite Sandwich Panels Under Blast Loads, Michelle Hoo Fatt, Leelaprasad Palla
Dr. Michelle S. Hoo Fatt
Analytical solutions were derived for the transient response and damage initiation of a foam-core composite sandwich panel subjected to blast loading. The panel response was modeled in two consecutive phases: (1) a through-thickness wave propagation phase leading to permanent core crushing deformations and (2) a transverse shear wave propagation phase resulting in global panel deflections. The predicted transient deformation of a sandwich panel consisting of E-glass vinyl ester facesheets and H100 PVC foam core compared well with ABAQUS predictions. Analytical predictions of the critical impulse for damage initiation in several foam sandwich panels also compared well with ABAQUS predictions.
A Three-Dimensional Constitutive Model For The Dynamic Response Of Rubber3, M. Liu, Michelle Hoo Fatt
A Three-Dimensional Constitutive Model For The Dynamic Response Of Rubber3, M. Liu, Michelle Hoo Fatt
Dr. Michelle S. Hoo Fatt
The development of a constitutive model to describe the dynamic response of a filled rubber compound is presented in this paper. A series of cyclic tension tests were done on the rubber compound with mean strains ranging from 0.2 to 0.5, strain amplitudes ranging from 0.05 to 0.2, and strain rates ranging from 0.1 to 10 s−1. The cyclic strain-controlled test results showed material rate dependence and hysteresis, and this motivated the development of a phenomenological-based, hyper-viscoelastic constitutive model. A Zener model, i.e., a spring in parallel with a Maxwell element, was assumed. The total stress was decomposed …
Blast Resistance And Energy Absorption Of Foam-Core Cylindrical Sandwich Shells Under External Blast, Michelle Hoo Fatt, Harika Surabhi
Blast Resistance And Energy Absorption Of Foam-Core Cylindrical Sandwich Shells Under External Blast, Michelle Hoo Fatt, Harika Surabhi
Dr. Michelle S. Hoo Fatt
The early time, through-thickness stress wave response of a foam-core, composite sandwich cylindrical shell under external blast is examined in this paper. Solutions for the transient response of the facesheets were derived as stress waves propagated through an elastic–plastic, crushable foam core. These solutions were found to be in good agreement with results from finite element analysis. The blast response of the composite sandwich cylindrical shell was shown to be affected by the magnitude and duration of the pressure pulse. High amplitude, low duration (impulsive) pressure pulses induced the greatest energy absorption. Low amplitude, long duration pressure pulses caused minimal …
Pressure Pulse Response Of Composite Sandwich Panels With Plastic Core Damping, Michelle Hoo Fatt, Pradeep Chapagain
Pressure Pulse Response Of Composite Sandwich Panels With Plastic Core Damping, Michelle Hoo Fatt, Pradeep Chapagain
Dr. Michelle S. Hoo Fatt
An analytical technique is presented for obtaining the large amplitude, damped response of a foam-core composite sandwich panel subjected to uniform pressure pulse loading. The predicted panel response was in agreement with finite element analysis, and it was used to examine the blast resistance of panels with various foam cores. Although blast resistance generally increased with the increasing core density, panels with the densest cores exhibited no energy absorption before panel failure. The panel with the PVC H200 foam also sustained higher failure pressure per unit areal weight density than the denser panels with Klegecell R300 and HCP100 foams.
Foam-Core, Curved Composite Sandwich Panels Under Blast, Michelle Hoo Fatt, Yifei Gao, Dushyanth Sirivolu
Foam-Core, Curved Composite Sandwich Panels Under Blast, Michelle Hoo Fatt, Yifei Gao, Dushyanth Sirivolu
Dr. Michelle S. Hoo Fatt
An elastic-plastic model was developed for predicting the blast response of a foam-core, curved composite sandwich panel. A multi-layered approach was used to distinguish facesheets and core deformations. Core compressibility and transverse shear through the thickness were accounted for using linear displacement fields through the thickness. The predicted solution from the elastic-plastic model was shown to compare well with FEA from ABAQUS Implicit. A parametric study showed that blast resistance of the sandwich shell is increased by allowing cores to undergo plastic crushing. Very thick and shallow shells derive much of their resistance to blast from core crushing. Strong, dense …
Transversely Isotropic Mechanical Properties Of Pvc Foam Under Cyclic Loading, Lingling Chen, Michelle Hoo Fatt
Transversely Isotropic Mechanical Properties Of Pvc Foam Under Cyclic Loading, Lingling Chen, Michelle Hoo Fatt
Dr. Michelle S. Hoo Fatt
yclic material tests were done on Divinycell PVC H100 foam to obtain out-of-plane and in-plane compression and shear material properties after foam yielding. The compression and shear stress–strain behaviors were very similar to each other except that a plateau (flow) stress occurred after yielding in compression, while the foam underwent mild strain hardening after shear yielding. The ratio of out-of-plane to in-plane stiffness and yield strength for the PVC H100 was found to be approximately 3/2 in both the compression and shear modes. After viscoplastic yielding, the foam underwent permanent damage and exhibited hysteresis, mainly in the form of viscoelasticity. …
Impact Perforation Of Sandwich Panels With Coremat®, Michelle Hoo Fatt, Dushyanth Sirivolu
Impact Perforation Of Sandwich Panels With Coremat®, Michelle Hoo Fatt, Dushyanth Sirivolu
Dr. Michelle S. Hoo Fatt
Analytical solutions for the quasi-static and low-velocity perforation of sandwich panels with woven roving E-glass/vinyl ester facesheets and Coremat were derived. A multi-stage perforation process involving delamination, debonding, core shear fracture and facesheet fracture was used to predict the quasi-static failure load and ballistic resistance of the panel. The high core-crushing resistance and damping of the Coremat resulted in rupture of the distal facesheet before the incident facesheet during panel perforation because they limited the amount of local indentation compared with global panel deformation. Analytical predictions of the quasi-static load-deflection response and the dynamic contact force history were within 10% …