Inspection & Testing of Composite Structures Flashcards

What is the purpose of ultrasonic testing in composites?

Answer: Detect internal flaws

Ultrasonic testing (UT) is a non-destructive testing method that uses high-frequency sound waves to detect internal flaws, such as voids, delaminations, and inclusions, within composite materials. The sound waves travel through the material and reflect off discontinuities, allowing technicians to identify and characterize defects that are not visible on the surface. This method is crucial for ensuring the structural integrity and safety of composite components.

Which inspection method uses visual observation?

Answer: Visual inspection

Visual inspection is the most basic and fundamental inspection method, relying on the human eye to detect surface defects, irregularities, or damage on composite materials. Technicians look for obvious flaws such as cracks, scratches, delaminations, voids, or improper resin distribution. While it cannot detect internal defects, it is an essential first step in quality control and often guides further, more advanced testing.

What is a common defect found during composite inspection?

Answer: Delamination

Delamination is a common and critical defect in composite materials, characterized by the separation of layers within the laminate. This can occur due to improper manufacturing, impact damage, or excessive stress, significantly reducing the material's structural integrity and load-bearing capacity. It is often detected through visual inspection, tap testing, or more advanced non-destructive methods like ultrasonic testing.

Which testing method uses X-rays to detect defects?

Answer: Radiography

Radiography, which includes X-ray and gamma-ray testing, is a non-destructive testing method that uses penetrating radiation to detect internal defects in composite materials. By passing radiation through the component and capturing the attenuated rays on a detector, technicians can create an image that reveals internal flaws like voids, inclusions, cracks, or delaminations that are not visible on the surface.

What is the goal of nondestructive testing (NDT)?

Answer: Identify defects nondestructively

The primary goal of nondestructive testing (NDT) is to evaluate the properties, integrity, and quality of a material, component, or system without causing any permanent damage to it. NDT methods allow for the detection of flaws, discontinuities, and variations in material characteristics, ensuring the safety and reliability of parts without compromising their future use.

Which defect is caused by air pockets within the composite?

Answer: Voids

Voids are small, entrapped air pockets or gas bubbles within the composite material, typically occurring during the manufacturing process due to insufficient resin impregnation or inadequate vacuum. These voids act as stress concentrators and can significantly reduce the mechanical strength, stiffness, and fatigue life of the composite part, making them a critical defect to avoid.

What does dye penetrant testing detect?

Answer: Surface cracks

Dye penetrant testing (DPT) is a non-destructive inspection method used to detect surface-breaking defects, such as cracks, porosity, and laps, in non-porous materials. A liquid penetrant is applied to the surface, allowed to dwell, and then removed. A developer is then applied, which draws the penetrant out of any surface discontinuities, making them visible.

Which instrument is used for visual inspection?

Answer: Borescope

A borescope is an optical instrument specifically designed for visual inspection of internal components or hard-to-reach areas without disassembly. It allows technicians to identify surface defects like cracks, delaminations, or foreign object debris in confined spaces. This makes it an invaluable tool for non-destructive visual examination in composite structures.

Why is documentation important in inspection?

Answer: Supports quality control and traceability

Documentation in inspection provides a detailed, verifiable record of findings, procedures, and decisions made during the process. This record is crucial for maintaining quality control by allowing verification against standards and ensuring traceability of repairs and inspections over time. It also serves as an essential reference for future maintenance, audits, and continuous improvement.