Understanding Failure Theories

What is the primary difference between failure in ductile and brittle materials?

• Ductile materials fail by fracture, brittle materials by plastic deformation.

• Ductile materials fail by plastic deformation, brittle materials by fracture.

• Both fail by fracture.

• Both fail by plastic deformation.

What does the Maximum Principal Stress theory state about material failure?

• Failure occurs when deviatoric stress is maximum.

• Failure occurs when shear stress exceeds yield strength.

• Failure occurs when principal stresses exceed yield or ultimate strengths.

• Failure occurs when hydrostatic stress is zero.

Why is the Maximum Principal Stress theory not ideal for ductile materials?

• It requires extensive experimental data.

• It only applies to brittle materials.

• It is too complex to apply.

• It does not account for hydrostatic stress.

What is the Tresca failure criterion also known as?

• Hydrostatic Stress theory

• Maximum Principal Stress theory

• Maximum Shear Stress theory

• Maximum Distortion Energy theory

What does the von Mises criterion focus on in terms of stress?

• Deviatoric stress

• Shear stress

• Hydrostatic stress

• Principal stress

Which failure theory is generally more conservative, Tresca or von Mises?

• Neither is conservative

• Tresca

• von Mises

• Both are equally conservative

What is a key feature of the von Mises yield surface?

• It forms a square.

• It forms an ellipse.

• It forms a triangle.

• It forms a circle.

What distinguishes failure theories for brittle materials from those for ductile materials?

• They consider the difference between tensile and compressive strengths.

• They require only one ultimate strength value.

• They are not affected by hydrostatic stresses.

• They are simpler to apply.

What does the Coulomb-Mohr theory account for in brittle materials?

• Only tensile strength

• Neither tensile nor compressive strengths

• Only compressive strength

• Both tensile and compressive strengths

Which theory is a special case of the Coulomb-Mohr failure theory?

• Maximum Principal Stress

• von Mises

• Tresca

• Modified Mohr