FREE Agricultural/Bioengineering Strength of Materials Questions and Answers
Why does stress not qualify as a fundamental feature yet strain does?
The stress is the fundamental characteristic since it can be calculated in a lab. Its value is unreliable.
Consider two identical bars, A and B, rigidly fastened between two rigid walls. A's bar has a higher thermal expansion coefficient than B's. What stresses are created as the temperature rises?
A rise in temperature will result in compressive strains in the bars because both supports are fixed and both bars will attempt to expand.
Which of the following answers is sufficient to compute the resulting change in diameter when a rod of length L and diameter D is subjected to a tensile load P?
We require the Young's modulus to calculate longitudinal strain and the Poisson's ratio to calculate transverse strain. E = 2G(1 + ) can be used to determine the Poissons ratio, however shear modulus is required.
Materials with an orthotropic structure have layers, such plywood or wood. For these materials, there are 9 independent elastic constants. Materials that are anisotropic or non-isotropic have varied characteristics in each direction. They behave in a non-homogeneous way. There are 21 elastic constants. How many elastic constants will there be in a non-isotropic, non-homogeneous material?
Materials that are anisotropic or non-isotropic exhibit varying characteristics in different directions. They behave in an inconsistent manner. There are 21 elastic constants in existence.
What is a material's characteristic that allows it to be pulled into thin wires?
Due to its ability to resist significant deformation, ductile material can be formed into wires. It may be formed into thin sheets thanks to its malleability.
If the Poissons ratio is equal to unity, the connection between Youngs modulus E and bulk modulus K will be .
As E = 2G(1 + μ) putting μ=1 we get E = -3K.
A cast iron T-section beam is bent only in one direction. The section's center of gravity measured from the flange side must be ___________ for the maximum compressive stress to be three times the maximum tensile stress.
If the applied moment is drooping, H/4. If the applied moment is not hogging, it is H/4. Since neither alternative is offered, we must choose hogging.
The term for a material in which significant deformation is feasible prior to complete failure by rupture is
Because the ductile material can withstand significant deformation before failing, it can be fashioned into wires.
The term "diagram" refers to a visual representation of the axial load variations for each segment of a beam's pan.
The stress graphic illustrates how the axial load varies across all pan sections. The bending moment diagram displays the moment variation in a beam. The fluctuation in shear force brought on by beam loading is depicted in the shear force diagram.
How can the bulk modulus (K) and rigidity modulus (G) be used to express the Poissons ratio?
Four elastic modulus correlations exist. The formula for the relationship between the bulk modulus, the rigidity modulus, and the Poissons ratio is given as = (3K - 2G) / (6K + 2G).
When a long bar is supported vertically and its lower end is loaded, the added weight causes additional stress. The level of tension will be .
The load per square inch is the stress. The bar will gain weight as a result of its loading on the lower end, which will raise the force in the upper cross-section and cause the maximum stress to occur at the built-in upper cross-section.
In the illustration, loads are carried by a stepped column. If the P/A ratio at this location is unity, what will be the maximum normal stress in the column at B in the larger diameter column?
Normal stress at B is defined as Total load operating at B / Area of a cross-section at B = (P + P) / 1.5 A = 2P/ 1.5A = 2/1.5.
How many elastic constants will there be in an isotropic, linear material?
Materials that are isotropic have uniform characteristics throughout. For these materials, there exist two independent elastic constants (E, G, K, and ), and if any two of these constants are known for any linear elastic and isotropic material, the other two can be deduced. Examples include gold, copper, aluminum, and steel.
What is the elastic bulk modulus?
For a particular material, it is found that the ratio of direct stress to the corresponding volumetric strain strain is constant when a body is subjected to mutually perpendicular like and equal direct stresses, provided that the deformation does not exceed a specified threshold. Bulk modulus is the name given to this ratio.
It is referred to as ___________ if the material has the same elastic characteristics in all directions.
Any substance with a consistent makeup is homogenous. In terms of the criteria, an elastic and a plastic differ.
What kind of test is used to evaluate a material's resistance to scuffing, abrasion, deformation, and indentation?
The term "hardness" refers to a substance's capacity to withstand scuffing, abrasion, deformation, and indentation. Therefore, the hardness test is employed to measure. Brinell, Rockwell, or Vickers hardness numbers are typically used to express it.