Lecture 5- Stress strain modulus and stiffness Flashcards
Is stiffness a material property? define stiffness
No, its dependent on dimensions. Resistance to change of shape
What are the moduli associated with tensile, shear, and hydrostatic pressure? State their unit
Youngs modulus (E)
Shear modulus (G)
Bulk modulus (K)
What is poisson’s ratio?
ratio of transverse strain to axial strain in tension
What does it mean for a material to be isotropic?
its properties are independent of the direction in which the material is being measured
What does it mean for a material to be anisotropic?
its properties are dependent on the direction in which the material is being measured
what are some ways stress can be applied without strain?
-thermal fields (heating)
-electric fields
-magnetic fields
What are the 4 stages of the selection strategy to choose a material?
-translation
-screening
-ranking
-documentation
What is translation in the selection strategy?
-translating design requirements into a prescription of the material
- identifying the conditions it has to meet and the goal of the product
What is screening in the selection strategy?
canceling all the materials that do not meet these requirements
What is ranking in the selection strategy?
ranking the remaining materials by their ability to meet your goal
What is documentation in the selection strategy?
documenting the top materials, so they can be explored more deeply
what are the 3 concepts used in the selection procedure?
performance indices
material selection charts
shape factors
whats a material index? provide examples
objective measures of performance
tensile strength
youngs modulus
whats are the 3 components of a performance index
Functional requirements
Geometric parameters
Properties of the material
what are the 4 types of loading
-tensile
-compression
-bending
-torsion
