What is a composite Doubler?

Composite doublers or repair patches provide an innovative repair technique which can enhance the way in which aircraft are maintained. Bonded repair of metallic aircraft structure is used to extend the life of flawed or under-designed components at reasonable cost.

What are the different types of repair in composite?

Types of Repair

• Resin Injection. This type of repair can be effective in limited instances, where the delamination is restricted to one ply.
• Semi-structural Plug/Patch. This type of repair can regain some strength.
• Structural Mechanically–fastened Doubler.

Can composite materials be repaired?

Introduction. Damaged composite structures are definitely repairable, shown clearly in the before and after images below. However, there are challenges: Hidden damage issues, including manufacturing defects.

What is a repair Doubler?

With traditional repairs a metallic patch or doubler is attached to the parent structure using bolts or rivets after removal of the cracked region. The aim is to restore mechanical properties, including: residual strength, stiffness, fatigue resistance and damage tolerance to an acceptable level.

How are composite planes repaired?

The steps involved in composite repair are:

1. Detect and assess the damage.
2. Identify component.
3. Remove Paint.
4. Design the repair.
5. Obtain materials and tools.
6. Remove the damaged area.
7. Effect the repair.
8. Allow proper curing time.

How do you fix a broken Composite?

Composite repair following a damage event usually involves a co-bond by scarfing out the damage area, laying in a film adhesive, adding pre-impregnated layers, bagging, and curing.

What is the most common method used for composite repairs?

Before a repair can be made, the extent of damage has to be determined. Ultrasonic testing (UT) equipment is the most common method for inspecting damage on composite aircraft structures. It sends high-frequency sound waves into the composite laminate and analyzes the reflections for damage and defects.

How do you fix a broken composite?

How is aircraft skin damage classified?

Stressed skin carries a large portion of the load imposed upon an aircraft structure. Various specific skin areas are classified as highly critical, semicritical, or noncritical. Minor damage to the outside skin of the aircraft can be repaired by applying a patch to the inside of the damaged sheet.

What is the meaning of composite repair?

Composite Repair refers to the process of using composite materials in order to repair damaged assets. Composites can be used to temporarily repair process piping, pipelines, heat exchangers, hoses, storage tanks, and other pressure vessels.

What can a composite doubler be used for?

Composite doublers or repair patches provide an innovative repair technique which can enhance the way in which aircraft are maintained. Bonded repair of metallic aircraft structure is used to extend the life of flawed or under-designed components at reasonable cost.

Can a composite doubler be used for riveting?

Instead of riveting multiple steel or aluminium plates to facilitate an aircraft repair, it is now possible to bond a single Boron-Epoxy composite doubler to the damaged structure.

Can a composite doubler survive a stress cycle?

The composite doublers produced significant crack growth mitigation when subjected to simulated pressure tension stress cycles. Even specimens with unabated fatigue cracks and co-located disbonds and impact damage were able to survive 144,000 fatigue cycles without specimen failure (< 2 in. crack growth).

When was a doubler bonded to a wing riser?

Doublers were bonded to the wing-risers between 1978 and 1992. This F-111 WPF repair represents the first bonded repair to primary structure.