Crowdly

A 1 m steel bar is deformed so that it is now 1.1 metres long, while the force is still being applied. Which of the following is true?

The engineering strain in the sample is 10%

The Poisson ratio tells us how much smaller the cross-section will now be

The true strain in the sample is 10%

The bar will remain exactly the same length once the force is removed

The sample cross-section will also be thinner than it was originally

True stress is always greater than engineering stress

True

False

Ionic bonding may be important to the modulus of which of the following?

hydrogen bonded materials

Which of the following answers is NOT true?

Elastic and plastic deformation are mutually exclusive; only one of them can occur at a given moment

Plastic deformation occurs in various different types of material, not just plastics

Elastic deformation is recoverable because none of the bonds within the material are broken

Plastic deformation occurs when bonds in a material are broken

Elastic modulus is dependent on the types of bonds that are present in a material, as well as other factors

Tensile stress is given by the symbol

and is defined as the

cross-sectional area

force

original length

The order of the following properties from smallest to largest for a typical ductile material is:

UTS < Yield stress < 0.2% proof stress

0.2% proof stress < UTS < Yield stress

UTS < 0.2% proof stress < Yield stress

Yield stress < UTS < 0.2% proof stress

Yield stress < 0.2% proof stress < UTS

0.2% proof stress < Yield stress < UTS

Hooke's Law is valid...(2 answers)

Only for metallic materials

Only in the plastic region

Only if the elastic region is entirely linear

For every type of material

Only in the elastic region

Only at the yield point

Ductility is a measure of a material's ability to be deformed without breaking. Why is ductility NOT just the same as fracture strain?

Because the fracture strain does not take into account work hardening.

Because the fracture strain is a measure of engineering or nominal strain, not true strain.

Because the fracture strain is only measured at fracture.

Because the fracture strain cannot be measured accurately during a test.

Because the fracture strain is the sum of elastic and plastic strain.

Elastic modulus is given by the symbol

and is defined as the