Elastic moduli

This site section presents an overview of the elastic moduli and the relevance of these properties for science and materials engineering. It also presents the different methods of characterization, both destructive and nondestructive, and discuss the strengths and weaknesses of each type and its variations. The purpose of this content is to provide the Engineer and Researcher the basic information about the elastic modulus, with particular focus on the methods of measurement, to facilitate the characterization and use of knowledge of these properties which are essential for all classes of materials.

Many materials when in service are subjected to forces or loads, such as aluminum alloy from which the wing of an airplane is built and the steel employed in the shaft of an automobile. In these situations it is necessary to know the characteristics of the material, such as elastic moduli, to design the pieces and devices so that any resulting deformation is predictable and not excessive to the point of plastic deformation, fatigue or even fracture.

The measurement of mechanical properties is done through carefully planned laboratory experiments, according to conditions governed by standards. In the specific case of elastic moduli, the methods may be dynamic, by vibrations with small amplitudes of deformation, or static, which subject the specimen to a known stress and simultaneously measure the strain induced. These tests may be conducted both at room temperature and at high temperatures with or without a controlled atmosphere.

The knowledge of elastic moduli has become object of attention of many professionals with different needs and applications, for example, producers and consumers of materials, research organizations and government agencies. Therefore consistency is a prime necessity in the conduction of tests. This consistency is achieved through the use of standardized testing techniques. The establishment and publication of these standard are often coordinated by professional societies. In Brazil, the ABNT (Brazilian Technical Standards Association) and in the United States the ASTM (American Society for Testing and Materials), among others, are responsible for the standardization of test materials. Its publications are updated annually and a series of standards relateds to the determination of elastic moduli.

Often, materials are selected for structural applications due to their desirable combinations of mechanical properties, such as stiffness (elastic modulus), mechanical strength, durability and economy of energy resources. The role of the structural engineers is to determine the stresses and distribution of stress that the materials are subject to. This can be obtained by experimental techniques and theoretical analysis of the stress which in-turn depends on the knowledge of the elastic moduli. Materials engineers and metallurgical engineers, on the other hand, are worried about the production and fabrication of materials to attend the service requirements as provided by this analysis of tension. This involves a necessary understanding of the relationship between the microstructure (i.e., the internal characteristics) of materials and their mechanical properties, which are directly correlated with the elastic moduli.

More details can be obtained at the link References and Publications

Composites elastic moduli characterization

Composites White Paper

This white paper presents the theory and proposal of a methodology for the non-destructive elastic moduli characterization of composites using the Impulse Excitation Technique.