ELASTIC DEFORMATION AND POISSON’S RATIO
ELASTIC DEFORMATION
AND
POISSON’S RATIO
E 45 – Materials, Friday 8:00 am
September 21, 2012
Due: October 19, 2012
Abstract
A tensile test was performed on a 4140 steel sample and the axial and transverse strains were measured. Data points were collected at incremental loads and graphed to determine the elastic modulus (30.4 x 106). Poisson’s ratio was also calculated from the dataset and determined to be 0.29. These experimental values agree closely (within 2%) to the textbook values of the steel sample. A sample of 7075 Aluminum was used in a cantilever beam test. Intermediate and end loads were place on the sample and the strain was measured at various distances from the loads. Using the dataset from the individual loads, the superposition strain was calculated and agreed within 7% of the experimental strain with both loads. From the measured deflection of the cantilever beam and the dataset, Young’s Modulus for the aluminum sample was determined to be 9.1x106 psi which agrees within 8% of the textbook value.
Introduction
To be able to decide on what kind of material to choose for product design, there are some critical characteristics you must consider in choosing a material prior to manufacturing. Characteristics such as material strength and flexibility are two tests that have been done on common materials for architects and engineers to reference during the design process. The purpose of this lab is to produce an elastic modulus of a material, and a predicted yield strength. Stress and strain data will be produced through tensile testing and cantilever beam testing.
For a tensile test, two strain gages will be attached to the material to measure the longitudinal strain and transverse stain. The percent elongation of the specimen is directly proportional to the change in longitudinal strain. With the dimensions of the original specimen, the change in these strains can tell us the
AND
POISSON’S RATIO
E 45 – Materials, Friday 8:00 am
September 21, 2012
Due: October 19, 2012
Abstract
A tensile test was performed on a 4140 steel sample and the axial and transverse strains were measured. Data points were collected at incremental loads and graphed to determine the elastic modulus (30.4 x 106). Poisson’s ratio was also calculated from the dataset and determined to be 0.29. These experimental values agree closely (within 2%) to the textbook values of the steel sample. A sample of 7075 Aluminum was used in a cantilever beam test. Intermediate and end loads were place on the sample and the strain was measured at various distances from the loads. Using the dataset from the individual loads, the superposition strain was calculated and agreed within 7% of the experimental strain with both loads. From the measured deflection of the cantilever beam and the dataset, Young’s Modulus for the aluminum sample was determined to be 9.1x106 psi which agrees within 8% of the textbook value.
Introduction
To be able to decide on what kind of material to choose for product design, there are some critical characteristics you must consider in choosing a material prior to manufacturing. Characteristics such as material strength and flexibility are two tests that have been done on common materials for architects and engineers to reference during the design process. The purpose of this lab is to produce an elastic modulus of a material, and a predicted yield strength. Stress and strain data will be produced through tensile testing and cantilever beam testing.
For a tensile test, two strain gages will be attached to the material to measure the longitudinal strain and transverse stain. The percent elongation of the specimen is directly proportional to the change in longitudinal strain. With the dimensions of the original specimen, the change in these strains can tell us the