Material testing and selection

Question 1

Describe the main features of a tensile test specimen

Answer 1

a long gauge length with a small cross section connected to a larger cross section either side. a smooth transition between the sections prevents stress concentrations

Question 2

What systems can be used to measure extension under load?

Answer 2

Strain gauges, contact type extensometer, video extensometers

Question 3

describe the vickers hardness test

Answer 3

a diamond pyramid shaped indentor is loaded using a dead weight into the material, creating an indent measured with a microscope

Question 4

how are vickers hardness numbers (HV) calculated?

Answer 4

HV= (2Forcesin(pyramid angle/2))/(d_average)^2

Question 5

Describe the four sections of material selection?

Answer 5

Translation : define the design requirements

Screening: eliminate materials which do not meet the constraints

Ranking: order the survivors using the objectives

Documentation: research top ranked candidates and consider culture constraints

Question 6

what factors impact the performance of a structural elements

Answer 6

functional requirements
geometric parameters
material properties

Question 7

What is the structural efficicency coefficient

Answer 7

the combination of the functions relating performance to functional requirements and geomentric requirements

Question 8

What is the material efficiency coefficient?

Answer 8

the function relating material properties to structural element performance