This article presents in a unified way, the various optimization criteria used by researchers for optimal placement of piezoelectric sensors and actuators on a smart structure. The article discusses optimal placement of piezoelectric sensors and actuators based upon six criteria: (i) maximizing modal forces/moments applied by piezoelectric actuators, (ii) maximizing deflection of the host structure, (iii) minimizing control effort/maximizing energy dissipated, (iv) maximizing degree of controllability, (v) maximizing degree of observability, and (vi) minimizing spill-over effects. Optimal piezoelectric sensor and actuator locations on beam and plate structures for each criterion and modes of interest are presented in a tabular form. This technical review has two objectives: (i) practicing engineers can pick the most suitable philosophy for their end application and (ii) researchers can come to know about potential gaps in this area.

A new scheme for active structural vibration control using piezoelectric patches at elevated temperatures is analytically derived and experimentally verified. A control law is derived using augmented piezoelectric constitutive equations which include the temperature dependence of piezoelectric stress coefficient (e 31 ) and permittivity (∈ 33 ). Since the temperature dependence of 'e 31 ' and '∈ 33 ' is not analytically known, their experimental values measured at elevated temperatures are used. Using augmented constitutive equations, a finite element model of a smart two-dimensional isotropic plate instrumented with a collocated piezoelectric sensor-actuator pair is derived. A control law for active vibration control of the first mode of the smart cantilevered plate is derived using negative velocity feedback. Active vibration control of the first mode of a smart cantilevered plate is experimentally achieved at elevated temperatures ranging from 25 to 75 • C under two cases: (i) using a control law which ignores the temperature dependence of 'e 31 ' and '∈ 33 ' and (ii) using a control law which includes the temperature dependence of 'e 31 ' and '∈ 33 '. A comparison between these two control laws shows that: (i) active vibration control (AVC) performance is not maintained at elevated temperatures using a control law which ignores the temperature dependence of 'e 31 ' and '∈ 33 ' and (ii) AVC performance is maintained at elevated temperatures when we use a control law which includes the temperature dependence of 'e 31 ' and '∈ 33 '.

Over 20 million burn injuries are reported every year, with severe cases requiring skin grafting. Traditionally, split thickness skin grafts are prepared by excising a small portion of healthy skin and its incision patterning using a suitable meshing device, which allows the graft to be expanded beyond its capacity. To date, the maximum expansion achieved through skin grafting has been reported to be less than three times, which is not sufficient for covering large burn sites with limited donor site skin. In this work, we have attempted to study skin graft expansion potential with novel auxetic patterns, which are known to exhibit negative Poisson's effect. Two‐layer skin graft models were developed using eight different auxetic incision patterns, and subjected to uniaxial and biaxial tensile strains. The Poisson's ratio, meshing ratio, and induced stresses were characterized for all graft models. The numerical results indicated expansion potentials greater than that of traditional skin grafts across all loads. Extremely high expansions (i.e., >30 times) were estimated for the I‐Shaped Re‐entrant and Rotating Triangles shaped auxetic models without rupture. Such pioneering findings are anticipated to initiate ground‐breaking advances towards skin graft research and improved outcomes in burn surgeries.

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