A Finite Element Analysis of Porosity Effects on Materials
Abstract
Porosity in materials greatly reduces the strength and load carrying characteristics of the material. Porosity is unavoidable in some materials (particularly ceramics) and is sometimes desirable for other reasons, such as radar reflection properties, diffusing a fluid through a material, and adjusting the heat transfer properties. In the past, the effects of porosity on material properties, particularly a materials modulus of elasticity (Young's modulus), have been determined, by fitting test data to one of three theoretical equation forms (linear, empirical exponential, and Hassin's semi-empirical equation, whichever fit the data best). These analytical equations all require that the effects of porosity on material properties be determined experimentally for several cases, and then other cases can be extrapolated. This limits accurate prediction before a material can be fully analyzed and produced. In this thesis a finite element model using MSC/NASTRAN is developed that can numerically determine the material's modulus of elasticity using the limited information from one material sample. The model is three dimensional, and simulates pores by placing small elements that are non-load bearing into the structure. These voids are randomly, and unevenly, distributed (using a Poisson distribution) to better simulate the response of a real porous material to a load. How much this porous model deforms can be used directly to calculate the porous modulus of elasticity.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216225
Entities
People
- Paul R. Woodmansee
Organizations
- Air Force Institute of Technology