A micromechanical model for 2-D triaxial braided composites is presented. The tow arrangement in the representative unit cell is modeled by solving the packing problem using analytical optimization, avoiding the need to measure the geometric properties experimentally. These results are used in the development of a closed-form micromechanical model predicting the full 3-D stiffness matrix of the...

A topology optimization problem in micromechanical resonator design is addressed in this paper. The design goal is to control the first several eigenfrequencies of a micromechanical resonator using topology optimization. The design variable is the distribution of mass in a constrained domain which we model via (1) the Simple Isotropic Material with Penalization Model and (2) the Peak Function M...

In this paper, we extend a class of micromechanical damage models by including initial stresses. The proposed approach is based on the solution of the Eshelby inhomogeneous inclusion problem in the presence of a pre-stress (in the matrix), adapted for elastic voided media. The closed form expression of the corresponding energy potential is used as the basis of various isotropic damage models co...

The mechanical behavior of soils has been traditionally described using continuum-mechanics-based models. These are empirical relations based on laboratory tests of soil specimens. The investigation of the soils at the grain scale using discrete element models has become possible in recent years. These models have provided valuable understanding of many micromechanical aspects of soil deformati...

This paper presents an analysis of the major mechanical component (the thorax) of the micromechanical flying insect (MFI), a centimeter sized aerial vehicle currently in development at UC Berkeley. We present a description of the kinematics of the mechanism which converts piezoelectric actuation into complex 3D wing motion. A complete non-linear modeling of the system based on the Lagrangian en...

This paper describes recent developments on the model identification and attitude control system for a Micmmechanical Flying lnsect (MFI). We include recently developed dynamical models for the thorax actuatom and various sensor models. Wing kinematic parameterization scheme was designed to generate feasible wing motions to decouple the body torques under the constraints of the thorax model. A ...