Deformation of Al85Y8Ni5Co2 Metallic Glasses under Cyclic Mechanical Load and Uniform Heating

Modelling of the deformation process of Al85Y8Ni5Co2 amorphous alloys was carried out under simultaneous application of cyclic mechanical load (at 0.3 or 3 Hz frequencies) and continuously increasing temperature (heating rate 5 K/min). It is shown that deformation of the amorphous specimens occurs by the hyperbolic temporal dependence. It is analytically determined and experimentally proved that for non-isothermal cyclic deformation, the wave effects take place as a result of the superposition of thermal-activated and mechanical components. The behaviour of the material under thermo-mechanical action was described qualitatively within the framework of Spaepen’s model. The dependencies for the reaction force of the samples were obtained as two-parameter functions of the frequency and temperature. A reaction force surface of a specimen, as a function of the different forcing frequencies and time, has been plotted.

Investigation of crack repair using piezoelectric material under thermo-mechanical loading

This article presents an experimental investigation of repair of a crack in a structure using piezoelectric material under thermo-mechanical loading environment. The cyclic mechanical load is applied on a plate with a straight and angular crack under uniform temperature environment. Two cases have been considered for the repair of crack under (a) mechanical loading and (b) thermo-mechanical loading environment. A piezoelectric sensor is utilized to measure voltage. The measured voltage is used to calculate the stress intensity factor in passive and active modes. The effect of a single and double piezoelectric patch in the repair of the plate is investigated. The double piezoelectric patch is found to be more effective as compared to single patch when placed symmetrically offset from the crack. An optimal value of voltage and phase difference is evaluated for most effective crack repair. Location of the piezoelectric patch is varied with respect to crack location, and best-suited position for effective crack repair is proposed. The viability of piezoelectric used for repair under thermo-mechanical loading is discussed. The active mode of repair by piezoelectric is found to be effective under thermo-mechanical loading environment.

Development of a Novel Model System to Study Remodeling of ECM Scaffolds in Response to Cyclic Stretching

In an effort to better understand the role of mechanical loading on the healing and remodeling of biological tissues, a number of in vitro models have been developed to apply either static or cyclic mechanical load to cell-seeded scaffolds (Huang 1993, Langelier 1999, Cacou 2000). The current study describes the validation of a new system designed to facilitate the study of matrix remodeling in cell seeded scaffolds, as well as the formation of tissue engineered scaffolds for potential use in repair of healing ligaments and tendons. Our objective was to develop a system that would allow a cell seeded scaffold to remain viable under cyclic loading for long periods of time, with the capability to apply complex loading regimes to the scaffold while monitoring the load in the scaffold.