Materials

Fatigue Test

FATIGUE TEST: A specimen is loaded repeatedly to a specific stress. The number of applications of the stress is counted until failure.

Charpy Test

CHARPY TEST: (Charpy V-notch test), a standardized beam specimen is given a 45 degree notch on the bottom of the beam.  The beam is then centered on simple supports where a falling pendulum drops from different heights and strikes the beam until failure. 

Creep Test

CREEP TEST: A low-tensile load of constant magnitude is applied to a specimen. The strain is then measured as a function of time. This test will determine the creep strength of a specimen, which is the stress that occurs at a specified creep rate.

Stress-Rupture Test

STRESS-RUPTURE TEST: Using the same procedure from the creep test. The Stress-Rupture Test provides the stress that results in a failure after a given amount of time.

On the Exam

Concrete testing shows up regularly on the FE exam — sampling, slump, air content, and compressive strength from cured cylinders. For official procedures, see ASTM’s concrete standards.

For official testing procedures and specifications, visit ASTM’s Concrete Standards page to explore the complete set of guidelines for concrete test methods.

On a Real Pour

Imagine a construction team preparing to pour concrete for the foundation of a new bridge. Before the full pour, they conduct a slump test on a sample batch to ensure the concrete has the right workability for placement and finishing. If the slump is too low, the mix might be too stiff to work with, while a high slump could indicate excessive water, weakening the final structure.

After pouring, the team casts several concrete cylinders from the same batch and cures them under controlled conditions. These cylinders are later subjected to a compressive strength test in a lab, where a machine applies increasing pressure until the sample breaks. This concrete test ensures the concrete meets the specified strength requirements before the bridge supports heavy loads. These common tests protect public safety by verifying concrete’s performance both during and after construction.

Material Structure

Isotropic: Mechanical behavior is the same in all directions • Anisotropic: Mechanical behavior is NOT the same in all directions • Homogeneous: Material has the same composition throughout • Non-homogeneous: Material DOES NOT have the same composition throughout • Mechanical Properties: Response of a material to external loads

Elastic Behaviour

Elastic Behavior: Instantaneous response to load. Member will return to original shape upon unloading • Linear Behavior: Has a straight-line-portion of the stress-strain diagram • Elastic Limit: Where a material transitions from elastic to plastic behavior • Plastic Behavior: Permanent deformations occur • Proportional Limit: Transition between linear and non-linear behavior • Yielding: Strain continues to increase with little to no change in stress

Strength and Failure

Ultimate Stress: Maximum stress on the stress-strain curve • Rupture Stress: Stress at which the specimen ruptures or fractures • Brittle: Has little plastic deformation before failure (ex. Glass, Concrete, Cast Iron) • Ductile: Has a lot of plastic deformation before failure (ex. Steel, Rubber) • Viscosity: Resistance to flow • Viscoelastic: Both elastic and viscous response, has a delayed response to loading

Time and Energy

Creep: Long-term deformation under constant load • Modulus of Resilience: Energy required to reach yield point • Toughness: Energy required to fracture • Failure: Operates outside of design limits • Factor of Safety: The ratio of a material’s strength to an expected strain (stress at failure/stress allowed)

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