ETC Materials Testing & Quality Assurance 3

Question 1

What does a control chart's Upper Control Limit (UCL) represent in a manufacturing process?

Accepted Answer

Three standard deviations above the process mean

Answer

The UCL is set at three standard deviations (3σ) above the process mean, indicating the upper boundary of normal process variation.

Question 2

A sample of concrete is tested at 28 days and fails to meet the specified compressive strength. Which standard governs acceptance criteria for concrete cylinder tests in the US?

Accepted Answer

ASTM C31 / ACI 318

Answer

ASTM C31 covers making and curing concrete test cylinders, and ACI 318 specifies the acceptance criteria based on 28-day compressive strength averages.

Question 3

In radiographic testing (RT), what does a higher film density number indicate?

Accepted Answer

The film is darker, indicating more radiation exposure

Answer

Film density is a logarithmic measure of film blackening; higher density means the film is darker due to greater radiation exposure.

Question 4

What is the significance of a material's fracture toughness (KIC)?

Accepted Answer

It quantifies a material's ability to resist crack propagation

Answer

Fracture toughness KIC is the critical stress intensity factor at which a pre-existing crack will propagate, used to predict catastrophic failure.

Question 5

When performing a liquid penetrant test (PT), what is the purpose of the developer step?

Accepted Answer

To draw entrapped penetrant out of discontinuities for visibility

Answer

The developer acts as a blotter, drawing penetrant back out of surface-breaking discontinuities and spreading it to create a visible indication.

(ETC) Engineering Technician Certification Practice Test

(ETC) Engineering Technician Certification Practice Test

ETC Materials Testing & Quality Assurance 3