ENGR 311 Exam 2 Questions and Answers Already Passed Latest Update 2025-2026
What is stress? - Answers Stress (σ) is the force applied per unit area, calculated as σ = F/A.
Define strain. - Answers Strain (ε) is the deformation per unit length, calculated as ε = ΔL/L₀.
What is Poisson's ratio? - Answers Poisson's ratio (ν) is the ratio of lateral to axial strain: ν = -
ε_lateral/ε_axial.
Describe the elastic region of the stress-strain curve. - Answers The elastic region is where
stress and strain are proportional (Hooke's Law), and deformation is reversible.
What is the yield strength? - Answers The yield strength is the stress at which permanent
(plastic) deformation begins.
What is ultimate tensile strength? - Answers The maximum stress a material can withstand
before necking, represented as the peak of the stress-strain curve.
List three strengthening mechanisms. - Answers Grain size reduction, solid-solution
strengthening, and strain hardening.
Define ductile fracture. - Answers Ductile fracture occurs with significant plastic deformation
before failure, typical in metals.
What are AX-type ceramic structures? - Answers Ceramic structures like rock salt, cesium
chloride, and zincblende, defined by cation-anion ratios.
Describe the structure of quartz. - Answers Quartz is crystalline SiO₂, arranged in a hexagonal
lattice.
What is the structure of glass? - Answers Glass is amorphous SiO₂, meaning it has a disordered,
non-crystalline structure.
What is a perovskite? - Answers A type of crystal structure (ABX₃) with applications in solar cells
and piezoelectric materials.
What is ionic bonding in ceramics? - Answers Ceramics with ionic bonds are generally brittle
and thermally insulating due to strong bonds.
What is diffusion? - Answers Diffusion is the movement of atoms from high to low
concentration areas.
Explain substitutional vacancy diffusion. - Answers Atoms move through vacancies in the lattice,
requiring high activation energy.
What is interstitial diffusion? - Answers Smaller atoms move through interstitial spaces,
requiring less activation energy.
What is stress? - Answers Stress (σ) is the force applied per unit area, calculated as σ = F/A.
Define strain. - Answers Strain (ε) is the deformation per unit length, calculated as ε = ΔL/L₀.
What is Poisson's ratio? - Answers Poisson's ratio (ν) is the ratio of lateral to axial strain: ν = -
ε_lateral/ε_axial.
Describe the elastic region of the stress-strain curve. - Answers The elastic region is where
stress and strain are proportional (Hooke's Law), and deformation is reversible.
What is the yield strength? - Answers The yield strength is the stress at which permanent
(plastic) deformation begins.
What is ultimate tensile strength? - Answers The maximum stress a material can withstand
before necking, represented as the peak of the stress-strain curve.
List three strengthening mechanisms. - Answers Grain size reduction, solid-solution
strengthening, and strain hardening.
Define ductile fracture. - Answers Ductile fracture occurs with significant plastic deformation
before failure, typical in metals.
What are AX-type ceramic structures? - Answers Ceramic structures like rock salt, cesium
chloride, and zincblende, defined by cation-anion ratios.
Describe the structure of quartz. - Answers Quartz is crystalline SiO₂, arranged in a hexagonal
lattice.
What is the structure of glass? - Answers Glass is amorphous SiO₂, meaning it has a disordered,
non-crystalline structure.
What is a perovskite? - Answers A type of crystal structure (ABX₃) with applications in solar cells
and piezoelectric materials.
What is ionic bonding in ceramics? - Answers Ceramics with ionic bonds are generally brittle
and thermally insulating due to strong bonds.
What is diffusion? - Answers Diffusion is the movement of atoms from high to low
concentration areas.
Explain substitutional vacancy diffusion. - Answers Atoms move through vacancies in the lattice,
requiring high activation energy.
What is interstitial diffusion? - Answers Smaller atoms move through interstitial spaces,
requiring less activation energy.
