DVD Process for Laminate Structures

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Which step involves using the tap test or ultrasonic test to map out the damage?

Step 2: Damage Removal

Step 5: Curing the Repair

Step 1: Investigating & Mapping the Damage (correct)

Step 3: Layup of the Repair Plies

What should be done after trimming out the damage to a smooth round or oval shape?

Applying Top Coat

Curing the Repair

Clean the surface with an approved solvent and cheese cloth. (correct)

Layup of the Repair Plies

Which method can improve the properties of a wet layup repair?

Use of scotch or sand paper

Heater blanket cure

SRM determination

Double Vacuum Debulk Method (DVD) (correct)

What is the temperature range at which most prepregs and film adhesives cure?

250 °F or 350 °F Signup and view all the answers

Why must the repair ply material and orientation match that of the parent structure?

To ensure a proper bond Signup and view all the answers

When should the vacuum bag be removed from the repair?

After curing and inspection Signup and view all the answers

What is the purpose of vacuum bagging in the repair process?

To reduce peel stresses at the edges of the repair Signup and view all the answers

What are typical failures found during inspection of lightning protection strips?

Disbonding from the radome surface Signup and view all the answers

What is a disadvantage of using an external patch in repairs?

Eccentric loading causing peel stresses Signup and view all the answers

Why are external patches usually stepped in repairs?

To reduce stress concentration at the edge Signup and view all the answers

Which materials can be used for external bonded repair according to the text?

Carbon, fiberglass, and Kevlar® Signup and view all the answers

What is important to avoid in lightning protection strips for a radome?

Protrusion into the air stream Signup and view all the answers

What is the purpose of the DVD process in wet layup laminates?

To remove entrapped air causing porosity Signup and view all the answers

How does the double vacuum bag process differ from a standard wet layup process?

It involves a debulking assembly for air removal Signup and view all the answers

What is the purpose of evacuating the air between the rigid outer box and inner vacuum bag in the double vacuum debulk principle?

To prevent atmospheric pressure from pressing down on the inner vacuum bag Signup and view all the answers

Why is it important to reduce resin viscosity during the debulking process?

To improve air and volatile removal Signup and view all the answers

What is the role of the DVD tool in preparing wet layup patches?

To facilitate patch preparation Signup and view all the answers

How does the double vacuum debulk principle help in preventing air bubbles in the laminate?

By preventing atmospheric pressure from pressing down on the inner vacuum bag Signup and view all the answers

What type of surfaces are precured patches not suitable for?

Compound curved surfaces Signup and view all the answers

In the repair process using precured patches, what is done in Step 3?

Consult the SRM for correct patch size Signup and view all the answers

What is required in Step 4 of using a precured patch for repair?

Apply film adhesive or paste adhesive to the damaged area Signup and view all the answers

What is a key advantage of bonded repairs over bolted repairs?

Stronger than original part material Signup and view all the answers

At what temperature do most film adhesives cure during the repair process with precured patches?

250 °F Signup and view all the answers

What type of surfaces are bonded repairs applicable to?

Any type of surface Signup and view all the answers

What is used to control the heat in the process described?

Thermocouples Signup and view all the answers

How is the debulking cycle completed?

By venting the vacuum source Signup and view all the answers

What is used to consolidate the plies during the compaction cycle?

Vacuum bag Signup and view all the answers

How are DVD tools fabricated according to the text?

From wood two-by-fours and plywood Signup and view all the answers

What is applied on the aircraft skin before placing the patch?

Film adhesive Signup and view all the answers

What is used to cure the adhesive used for patch installation?

Vacuum bag and heater blanket Signup and view all the answers