A novel test fixture for mode III fracture characterization of monolithic laminates and composite sandwich specimens

2021 ◽  
pp. 002199832110201
Author(s):  
Pietro Sabbadin ◽  
Christian Berggreen ◽  
Brian Nyvang Legarth ◽  
Lujin Lin
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Mode Iii ◽  
Fracture Characterization ◽  
Test Fixture ◽  
Composite Sandwich ◽  
Non Linear

This work presents a novel test fixture for mode III fracture characterization of delaminations in monolithic laminates and face-core debonds in foam core composite sandwich specimens. The test fixture is configured as an extension of the already existing shear-torsion-bending (STB) test designed for monolithic laminates. The specimen sizing, lay-up configuration and the manufacturing process are presented. Accordingly, an overview of the test fixture is provided along with the data reduction method employed to compute the energy release rate. The results from representable fracture characterization tests are presented as force vs. displacement curves, where different definitions of the critical load for crack propagation can be defined. Thus, the critical value of the energy release rate is computed using analytically based equations for the different definitions given for the critical loads. The results show a stable crack growth for monolithic laminate specimens. However, a highly non-linear response of the sandwich specimens, before the onset of crack propagation, is observed. A non-linear numerical analysis and destructive specimen inspections are carried out in order to identify the source of the non-linear behaviour observed in the experimental results.

The Mode III Interface Crack in Piezo-Electro-Magneto-Elastic Dissimilar Bimaterials

2005 ◽  
Vol 73 (2) ◽  
pp. 220-227 ◽  
Author(s):  
R. Li ◽  
G. A. Kardomateas
Keyword(s):  
Magnetic Field ◽  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Interface Crack ◽  
Release Rate ◽  
Mode Iii ◽  
Electro Magnetic Field ◽  
Magnetic Loading ◽  
Electro Magnetic

The mode III interface crack problem is investigated for dissimilar piezo-electro-magneto-elastic bimaterial media, taking the electro-magnetic field inside the crack into account. Closed form solutions are derived for impermeable and permeable cracks. The conventional singularity of r−1∕2 is found for the fields at the distance r ahead of the interface crack tip. Expressions for extended crack tip stress fields and crack opening displacements (ECODs) are derived explicitly, and so are some fracture parameters, such as extended stress intensity factors (ESIFs) and energy release rate (G) for dissimilar bimaterials. An approach called the “energy method,” finding the stationary point of the saddle surface of energy release rate with respect to the electro-magnetic field inside the crack, is proposed. By this method, the components of the induced electro-magnetic field inside the crack are determined, and the results are in exact agreement with those in the literature if the two constituents of the bimaterial media are identical. The effects from mechanical and electro-magnetic property mismatches, such as differences in the stiffness, electric permittivity and magnetic permeability, between the two constituents of the bimedia on the mode III interface crack propagation are illustrated by numerical simulations. The results show that the applied electric and magnetic loading usually retard the growth of the interface crack and the directions of the combined mechanical, electric, and magnetic loading have a significant influence on the mode III interface crack propagation.

scholarly journals Effect of the Characteristic Size and Content of Graphene on the Crack Propagation Path of Alumina/Graphene Composite Ceramics

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 611
Author(s):  
Benshuai Chen ◽  
Guangchun Xiao ◽  
Mingdong Yi ◽  
Jingjie Zhang ◽  
Tingting Zhou ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Volume Content ◽  
Phase Interface ◽  
Average Energy ◽  
Characteristic Size ◽  
Composite Ceramics ◽  
Graphene Composite

In this paper, the Voronoimosaic model and the cohesive element method were used to simulate crack propagation in the microstructure of alumina/graphene composite ceramic tool materials. The effects of graphene characteristic size and volume content on the crack propagation behavior of microstructure model of alumina/graphene composite ceramics under different interfacial bonding strength were studied. When the phase interface is weak, the average energy release rate is the highest as the short diameter of graphene is 10–50 nm and the long diameter is 1600–2000 nm. When the phase interface is strong, the average energy release rate is the highest as the short diameter of graphene is 50–100 nm and the long diameter is 800–1200 nm. When the volume content of graphene is 0.50 vol.%, the average energy release rate reaches the maximum. When the velocity load is 0.005 m s−1, the simulation result is convergent. It is proven that the simulation results are in good agreement with the experimental phenomena.

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.

Finite Element Modeling for Energy Release Rate in Human Cortical Bone

Volume 2 ◽  
2004 ◽  
Author(s):  
Saiphon Charoenphan ◽  
Apiwon Polchai
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Finite Element Modeling ◽  
Energy Release Rate ◽  
Cortical Bone ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Slow Crack Growth ◽  
Finite Element Models

The energy release rates in human cortical bone are investigated using a hybrid method of experimental and finite element modeling techniques. An explicit finite element analysis was implemented with an energy release rate calculation for evaluating this important fracture property of bones. Comparison of the critical value of the energy release rate, Gc, shows good agreement between the finite element models and analytical solutions. The Gc was found to be approximately 820–1150 J/m2 depending upon the samples. Specimen thickness appears to have little effect on the plane strain condition and pure mode I assumption. Therefore the energy release rate can be regarded as a material constant and geometry independent and can be determined with thinner specimens. In addition, the R curve resulting from the finite element models during slow crack growth shows slight ductility of the bone specimen that indicates an ability to resist crack propagation. Oscillations were found at the onset of the crack growth due to the nodal releasing application in the models. In this study light mass-proportional damping was used to suppress the noises. Although this techniques was found to be efficient for this slow crack growth simulation, other methods to continuously release nodes during the crack growth would be recommended for rapid crack propagation.

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