Enhancing Fracture Toughness and Stress Energy Release Rate of Vinyl Ester Matrix Using Dual Reinforcement of CNT and GNP

MRS Advances ◽  
2018 ◽  
Vol 3 (15-16) ◽  
pp. 867-873
Author(s):  
Christopher Gapstur ◽  
Hassan Mahfuz ◽  
Javad Hashemi ◽  
Andrew C. Terentis
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Vinyl Ester ◽  
Strain Energy Release ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Interface Sliding

ABSTRACTIn this paper, we report a method of increasing fracture toughness (KIC) and strain energy release rate (GIC) of vinyl ester matrix by adopting a dual reinforcement strategy. Reinforcements were carbon nanotubes (CNT) and graphene nanoplatelets (GNP). Both categories of nanoparticles were functionalized with COOH. The idea was to enhance crack bridging and interface sliding with CNT inclusions, given their high aspect ratio. In addition, promote crack-tip blunting and cross-linking density with GNP inclusions, due to their platelet structures. Both KIC and GIC were measured using ASTM D5045-14. An exhaustive experimental study revealed an optimum loading of both nanoparticles to be 0.25 wt% CNT and 0.5 wt% GNP, based on the highest combination of KIC and GIC values. We observed that stress intensity factor, KIC, of neat vinyl ester increased by 43% from 1.14 to 1.62 MPa*(m½). Meanwhile, the improvement in GIC was even greater with an increase of 65%, i.e., from 370 to 610 J/(m2). Differential scanning calorimetry (DSC) studies showed a discernible shift in glass transition temperature (Tg) from 123 to 128°C. The slight temperature increase was similar in thermogravimetric analysis (TGA). We observed the maximum thermal decomposition temperature (Tp) increase from 410 to 414°C, as was evident in the derivative TGA (DTG) curves.

Mode I Fracture Toughness of a Tri-Layered Beam with Interfacial Crack

2012 ◽  
Vol 166-169 ◽  
pp. 245-248
Author(s):  
Shiuh Chuan Her ◽  
Wei Bo Su
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Mode I ◽  
Analytical Prediction ◽  
Layered Beam

A tri-layered cracked beam under opening loading is developed for the interfacial fracture toughness measurement. Determination of the mode I strain energy release rate along the second and third layers of the tri-layered beam is carried out analytically. The analytical prediction of the strain energy release rate is validated with the finite element results. The influences of the layer thickness and Young’s modulus on the strain energy release rate are examined through a parametric study.

scholarly journals Caracterização da tenacidade à fratura de materiais de fricção e critérios de projetos

Exacta ◽  
2011 ◽  
Vol 9 (3) ◽  
pp. 301-308
Author(s):  
Alexandre Casaril ◽  
Carlos Henrique Selle Pereira ◽  
Carlos Pérez Bergmann ◽  
Hazim Ali Al-Qureshi
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Plane Strain Fracture Toughness ◽  
Plastic Materials ◽  
Strain Fracture

Este trabalho foi realizado com objetivo de caracterizar materiais de fricção atualmente utilizados em veículos pesados para linha de montagem e reposição. Cinco materiais de fricção foram analisados através de testes mecânicos realizados com base na norma ASTM D5045-99 (Reapproved 2007) – Plane Strain Fracture Toughness and Strain Energy Release Rate of plastic Materials. Os resultados de KIC dos cinco materiais foram da ordem de 1 MPa.m1/2, corroborando com o esperado para materiais de matriz fenólica. Adicionalmente, os resultados de KIC são representativos da fragilidade dos materiais de fricção. A análise estatística foi realizada utilizando a metodologia de Weibull, permitindo estabelecer probabilidades de ocorrência de KIC menor do que um valor aleatoriamente escolhido. Dessa forma, do ponto de vista de projeto é possível estabelecer critérios de falha, evitando o investimento de recursos em protótipos que venham a falhar em campo.

scholarly journals Toughening of Epoxy Resin: The Effect of Water Jet Milling on Worn Tire Rubber Particles

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 529 ◽  
Author(s):  
Peter Tamas-Benyei ◽  
Eniko Bitay ◽  
Hajime Kishi ◽  
Satoshi Matsuda ◽  
Tibor Czigany
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Charpy Impact ◽  
Strain Energy Release ◽  
Water Jet ◽  
Rubber Particles

In this work a cycloaliphatic amine-cured epoxy (EP) resin was modified by micron-scale rubber particles (RP). Nominal RP, in sizes of 200 and 600 µm respectively, were produced using worn truck tires and ultra-high-pressure water jet cutting. The RP were dispersed into the EP resin using different mixing techniques (mechanical, magnetic, and ultrasonic stirring) prior to the introduction of the amine hardener. The dispersion of the RP was studied using optical light microscopy. A longer mixing time reduced the mean size of the particles in the EP compounds. Static (tensile and flexural), dynamic (unnotched Charpy impact), and fracture mechanical (fracture toughness and strain-energy release rate) properties were determined. The incorporation of the RP decreased the stiffness and strength values of the modified EPs. In contrast, the irregular and rough surface of the RP resulted in improved toughness. The fracture toughness and strain-energy release rate were enhanced up to 18% owing to the incorporation of 1% by weight (wt%) RP. This was traced to the effects of crack pinning and crack deflection. Considerably higher improvement (i.e., up to 130%) was found for the unnotched Charpy impact energy. This was attributed to multiple cracking associated with RP-bridging prior to final fracture.

On the Axial Rigidity of a Perforated Strip and the Strain Energy Release Rate in a Centrally Notched Strip Subjected to Uniaxial Tension

1964 ◽  
Vol 86 (4) ◽  
pp. 693-697 ◽  
Author(s):  
R. G. Forman ◽  
A. S. Kobayashi
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Uniaxial Tension ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Theoretical Studies ◽  
Correction Factors ◽  
Elasticity Solutions

This paper presents theoretical studies on the axial rigidities in strips with circular and elliptical perforations and subjected to uniaxial tension. Greenspan’s original derivations on these axial rigidities [2] were improved by using the elasticity solutions by Howland [6] and Ishida [7] for infinite strips with circular and elliptical perforations, respectively. Finally, the correction factors for centrally notched strips subjected to uniaxial tension were rederived from the above results following the energy approach by Irwin and Kies [3].

Shape and energies of a dynamically propagating crack under bending

2003 ◽  
Vol 18 (10) ◽  
pp. 2379-2386 ◽  
Author(s):  
Dov Sherman ◽  
Ilan Be'ery
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Crack Front ◽  
Three Dimensional ◽  
Strain Energy Release ◽  
Governing Parameter ◽  
Propagating Crack ◽  
Front Shape

We report on the exact shape of a propagating crack in a plate with a high width/thickness ratio and subjected to bending deformation. Fracture tests were carried out with brittle solids—single crystal, polycrystalline, and amorphous. The shape of the propagating crack was determined from direct temporal crack length measurements and from the surface perturbations generated during rapid crack propagation. The shape of the crack profile was shown to be quarter-elliptical with a straight, long tail; the governing parameter of the ellipse axes is the specimen's thickness at most length of crack propagation. Universality of the crack front shape is demonstrated. The continuum mechanics approach applicable to two-dimensional problems was used in this three-dimensional problem to calculate the quasistatic strain energy release rate of the propagating crack using the formulations of the dynamic energy release rate along the crack loci. Knowledge of the crack front shape in the current geometry and loading configuration is important for practical and scientific aspects.

Nonlinear Approach for Strain Energy Release Rate in Micro Cantilevers

2010 ◽  
Author(s):  
Arash Kheyraddini Mousavi ◽  
Seyedhamidreza Alaie ◽  
Maheshwar R. Kashamolla ◽  
Zayd Chad Leseman
Keyword(s):  
Surface Roughness ◽  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Rigid Substrate ◽  
Micro Cantilever

An analytical Mixed Mode I & II crack propagation model is used to analyze the experimental results of stiction failed micro cantilevers on a rigid substrate and to determine the critical strain energy release rate (adhesion energy). Using nonlinear beam deflection theory, the shape of the beam being peeled off of a rigid substrate can be accurately modeled. Results show that the model can fit the experimental data with an average root mean square error of less than 5 ran even at relatively large deflections which happens in some MEMS applications. The effects of surface roughness and/or debris are also explored and contrasted with perfectly (atomically) flat surfaces. Herein it is shown that unlike the macro-scale crack propagation tests, the surface roughness and debris trapped between the micro cantilever and the substrate can drastically effect the energy associated with creating unit new surface areas and also leads to some interesting phenomena. The polysilicon micro cantilever samples used, were fabricated by SUMMIT V™ technology in Sandia National Laboratories and were 1000 μm long, 30 μm wide and 2.6 μm thick.

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