Dynamic analysis of two collinear electro-magnetically dielectric cracks in a piezoelectromagnetic material is made under in-plane magneto-electro-mechanical impacts. Generalized semi-permeable crackface boundary conditions are proposed to simulate realistic opening cracks with dielectric. Ideal boundary conditions of a combination of electrically permeable or impermeable and magnetically perme...

This paper investigates the phenomenon of slant fracture observed in stable tearing tests of many ductile materials, where an initially flat crack, loaded under remote Mode I conditions, tends to grow into a slant crack and stay in the slant configuration until final fracture. In an effort to identify potential reasons why cracks prefer to grow in a slant manner, three-dimensional finite elemen...

Finite element analysis of the delamination crack propagation in laminated composites is presented. Fracture mechanics based Virtual Crack Closure Technique (VCCT), and the cohesive element technique, have been used to simulate the delamination initiation and propagation under Mode-I type loading. Detailed description of the parameter selection process for these two techniques with ABAQUS®/Stan...

We investigate theoretically statistics and thermally activated dynamics of crack nucleation and propagation in a two-dimensional heterogeneous material containing quenched randomly distributed defects. We consider a crack tip dynamics accounting for dissipation, thermal noise and the random forces arising from the elastic interactions of the crack opening with the defects. The equation of moti...

While the formation of cracks is often stochastic and considered undesirable, controlled fracture would enable rapid and low cost manufacture of micro/nanostructures. Here, we report a propagation-controlled technique to guide fracture of thin films supported on soft substrates to create crack arrays with highly controlled periodicity. Precision crack patterns are obtained by the use of strateg...

This paper describes the crack sensing performance of a wireless and passive smart-skin sensor designed as a folded patch antenna. When strain/deformation occurs on the patch antenna, the antenna’s electrical length changes and its electromagnetic resonance frequency also changes accordingly. An inexpensive off-the-shelf radiofrequency identification (RFID) chip is adopted in the sensor design ...

Recent finite-element results by S. Cl. Larsson and A. J. Carlsson suggest a limited range of validity to the ‘small scale yielding approximation’, whereby small crack tip plastic zones are correlated in terms of the elastic stress intensity factor, It is shown with the help of a model for plane strain yielding that their results may be explained by considering the non-singular stress, acting p...

We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocit...

Further results are presented for the direct problem of scattering of high-frequency waves by cracks in elastic solids. Results for a penny-shaped crack, obtained on the basis of geometrical diffraction theory, are compared with experimental data. For simple crack geometries a hybrid method, whereby the crack-opening displacement is computed by ray theory, and the scattered field is subsequentl...

This paper studied the effects of reinforcement corrosion on bond performance between rebar and concrete. Tests were carried out to evaluate the degradation of bond between reinforcing steel and concrete for different corrosion levels of reinforcing steel. A series of 20 specimens of different concrete strength with various reinforcing steel corrosion levels were designed and manufactured. Each...