Design of laminated piezocomposite shell transducers with arbitrary fiber orientation using topology optimization approach

Sensor and actuator based on laminated piezocomposite shells have shown increasing demand in the field of smart structures. The distribution of piezoelectric material within material layers affects the performance of these structures; therefore, its amount, shape, size, placement, and polarization should be simultaneously considered in an optimization problem. In addition, previous works suggest the concept of laminated piezocomposite structure that includes fiber-reinforced composite layer can increase the performance of these piezoelectric transducers; however, the design optimization of these devices has not been fully explored yet. Thus, this work aims the development of a methodology using topology optimization techniques for static design of laminated piezocomposite shell structures by considering the optimization of piezoelectric material and polarization distributions together with the optimization of the fiber angle of the composite orthotropic layers, which is free to assume different values along the same composite layer. The finite element model is based on the laminated piezoelectric shell theory, using the degenerate three-dimensional solid approach and first-order shell theory kinematics that accounts for the transverse shear deformation and rotary inertia effects. The topology optimization formulation is implemented by combining the piezoelectric material with penalization and polarization model and the discrete material optimization, where the design variables describe the amount of piezoelectric material and polarization sign at each finite element, with the fiber angles, respectively. Three different objective functions are formulated for the design of actuators, sensors, and energy harvesters. Results of laminated piezocomposite shell transducers are presented to illustrate the method. Copyright (C) 2012 John Wiley & Sons, Ltd.

Archaeofacies Analysis: Using Depositional Attributes to Identify Anthropic Processes of Deposition in a Monumental Shell Mound of Santa Catarina State, Southern Brazil

In the coast of Santa Catarina State (southern Brazil), a large population of monumental shell mounds characterizes a highly dynamic coastal setting. In this paper, sedimentary facies analysis was adapted for description, sampling, and interpretation of shell mound complex and repetitive archaeostratigraphic successions. Archaeofacies identification in the field, according to depositional attributes, is tested by contrasting field description with multi-element chemical analyses, total carbon and nitrogen determinations, and micromorphological descriptions. Two vertical sequences at the black deposit of Jabuticabeira II shell mound were studied and preliminary results showed that: (1) depositional attributes are a reliable base for archaeofacies identification in the field, (2) the formation process of this site involved a sequence of anthropic depositional processes, where burned refuse was redeposited over the shell mound following a ritual construction pattern, and (3) the black deposit includes a double palimpsest that refers to provenance and meaning of mound construction material. (C) 2009 Wiley Periodicals, Inc.