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In this paper a new approach about relation of Acoustic Emission(AE) method and mechanical properties of ferrite-martensite dual phase steels(DPS) has presented. The AE signals from a tensile test using a range of DPS with different volume fractions of martensite (VM)s, in the range of 12–65% VM, were obtained and their AE signals were investigated. In order to better study DPS internal behaviour, a function named “sentry function” was used. The amount of this function depends on the strain energy and acoustic emission energy. the Results show that AE monitoring and sentry function are efficient tools for detection of micromechanisms, consisting of Ferrite-Martensite interface decohesion and/or martensite phase fracture, identifying the correlation of failure mechanisms to microstructure in DPS.

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In this paper, the effect of shape memory alloy on low-velocity impact response of rectangular sandwich plates with composite facesheets and soft auxetic cores is investigated using a new higher-order global–local hyperbolic plate theory. In order to obtain accurate results with the least error, non-uniform and time-dependent distribution for the phases of SMA and the transverse compliance of the soft core are considered. Also, a refined contact law is proposed instead of using the traditional Hertz law and different contact laws are considered for the loading and unloading phases. Stiffness effects of all layers along with the effect of plate thickness on contact stiffness are considered. The obtained nonlinear finite element governing equations are solved by making use of an iterative algorithm at each time step. The results of the present study are compared with the experimental results in other references, and it is proved that the results are valid. Finally, the effect of auxetic core, core Poisson's ratio, SMA wires, and indenter energy on impact response of composite sandwich plat are investigated. The results show that the auxetic core increases the apparent stiffness of the contact area that causes an increase in impact forces and a decrease in the lateral deflection and impact duration. Besides, the SMA can absorb a remarkable portion of the stored impact-induced strain energy due to the superelastic and hysteretic natures of the SMA material, which results in increasing impact strength of the sandwich plate and decreasing the damage caused due to the impact.