3 Material Properties and Testing Free Online FlashCards

What is density, and how is it calculated?

Density is mass per unit volume: $\rho = \frac{m}{V}$. It matters when weight or inertia is important.

What does porosity measure?

Porosity is the fraction of a material’s volume occupied by pores. It can affect strength, permeability, and heat transfer.

What does thermal conductivity indicate?

Thermal conductivity measures how readily heat flows through a material. High conductivity spreads heat effectively; low conductivity can provide insulation.

What is specific heat capacity?

Specific heat capacity is the heat needed to raise a unit mass of a material by one degree. It is commonly measured calorimetrically.

How is the linear thermal expansion coefficient estimated?

The linear expansion coefficient is approximately $\alpha = \frac{\Delta L}{L_0\Delta T}$, relating length change to initial length and temperature change.

How is a uniform specimen’s resistivity calculated?

For a uniform specimen, resistivity is calculated from resistance, length, and cross-sectional area: $\rho = \frac{RA}{L}$.

Why use a four-probe electrical measurement?

Four-probe measurements help reduce errors from electrical lead and contact resistance, especially for low-resistance samples.

What determines a material’s chemical compatibility?

Compatibility depends on the specific material and service conditions, including exposure to substances such as acids, salts, moisture, or solvents.

How is corrosion commonly compared in a laboratory test?

A common comparison exposes prepared specimens to a defined environment, measures mass loss, and calculates a corrosion rate. Conditions and specimen preparation must be controlled.

How is engineering stress calculated?

Engineering stress is applied force divided by the specimen’s original cross-sectional area: $\sigma = \frac{F}{A_0}$.

How is engineering strain calculated?

Engineering strain is the change in gauge length divided by its original length: $\varepsilon = \frac{\Delta L}{L_0}$. It is dimensionless.

What does Young’s modulus measure?

Young’s modulus is the initial slope of a linear stress–strain curve and measures stiffness.