טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGivli Josef
SubjectMechanical Behavior of Heterogeneous Structures
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Emeritus Eli Altus


Abstract

The technology of the 21st century poses new engineering challenges, particularly in the design and manufacturing of advanced mechanical devices. Leading directions are the miniaturization of structures and biological-mechanical applications. In these structures heterogeneity is dominant, and “macro-engineering” concepts are not always applicable. Even current Micro/Nano structures are commonly heterogeneous, with stochastic material properties (elastic, thermal, optical etc.), characterized by a microstructure in the same (size) order of the structure itself. A major challenge is to be able to characterize the response of such heterogeneous structures. While the behavior of infinite heterogeneous structures (infinitely small characteristic length of heterogeneity) has been extensively studied within the concept of effective properties, the analysis of structures with a finite size heterogeneity is still embryonic. Recent works have demonstrated that the behavior of finite-size heterogeneous structures is significantly affected by the inherent non-homogeneous morphology.  Interestingly, it has been found that the reliability of the structure can be improved considerably by controlling certain morphological characteristics during manufacturing.

In this work the effect of heterogeneity (either stochastic or deterministic) on the mechanical response of the structure is studied. The analysis is essentially analytical, and is based on the Functional Perturbation Method (FPM) that has been developed and generalized in the past few years. Analytical results have been compared to numerical (Finite elements, Monte-Carlo) simulations and found to be in good agreement.