A review of impact testing on marine composite materials: Part III - Damage tolerance and durability

2018 ◽  
Vol 188 ◽  
pp. 512-518 ◽  
Author(s):  
L.S. Sutherland
Keyword(s):  
Composite Materials ◽  
Damage Tolerance ◽  
Impact Testing ◽  
Marine Composite

Progressive Fracture Evaluation in Composite Materials by Acoustic Emission Technique

2011 ◽  
Vol 465 ◽  
pp. 535-538 ◽  
Author(s):  
Milad Hajikhani ◽  
Amir Refahi Oskouei ◽  
Mehdi Ahmadi Najaf Abadi ◽  
Amir Sharifi ◽  
Mohammad Heidari
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Structural Design ◽  
Composite Laminates ◽  
Damage Tolerance ◽  
Acoustic Emission Technique ◽  
Out Of Plane ◽  
Progressive Fracture ◽  
Laminar Fracture ◽  
Delamination Propagation

Glass/polyester and glass/epoxy laminated composites widely used in structures and have very near properties. These composite laminates have poor inter-laminar fracture resistance and suffer extensive damage by delamination cracking when subjected to out of plane loading and hence are vulnerable to delamination. The presence of delamination in the composite material may reduce the overall stiffness. Structural design and nondestructive test techniques have evolved as increased emphasis has been placed on the durability and damage tolerance of these materials. There are several methods used to investigate damages of composite materials. Acoustic emission is one of these. In this work the effect of delamination propagation on acoustic emission (AE) events in glass/polyester and glass/epoxy composites is obtained also Fracture surface examinations were conducted using a scanning electron microscope (SEM) and results in these two common composites compared. Consequently, revealed that the AE technique is a practicable and effective tool for identifying and separating kinds of cracks in these composites.

Fracture mechanical behaviour of laser beam-welded AA2198 butt joints and integral structures

2015 ◽  
Vol 6 (6) ◽  
pp. 787-798 ◽  
Author(s):  
Nikolai Kashaev ◽  
Stefan Riekehr ◽  
Kay Erdmann ◽  
Alexandre Amorim Carvalho ◽  
Maxim Nurgaliev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Laser Beam ◽  
Damage Tolerance ◽  
Fracture Behaviour ◽  
Butt Joints ◽  
Metallic Structures ◽  
Mechanical Fracture ◽  
Content Type ◽  
Integral Structures

Purpose – Composite materials and metallic structures already compete for the next generation of single-aisle aircraft. Despite the good mechanical properties of composite materials metallic structures offer challenging properties and high cost effectiveness via the automation in manufacturing, especially when metallic structures will be welded. In this domain, metallic aircraft structures will require weight savings of approximately 20 per cent to increase the efficiency and reduce the CO2 emission by the same amount. Laser beam welding of high-strength Al-Li alloy AA2198 represents a promising method of providing a breakthrough response to the challenges of lightweight design in aircraft applications. The key factor for the application of laser-welded AA2198 structures is the availability of reliable data for the assessment of their damage tolerance behaviour. The paper aims to discuss these issues. Design/methodology/approach – In the presented research, the mechanical properties concerning the quasi-static tensile and fracture toughness (R-curve) of laser beam-welded AA2198 butt joints are investigated. In the next step, a systematic analysis to clarify the deformation and fracture behaviour of the laser beam-welded AA2198 four-stringer panels is conducted. Findings – AA2198 offers better resistance against fracture than the well-known AA2024 alloy. It is possible to weld AA2198 with good results, and the welds also exhibit a higher fracture resistance than AA2024 base material (BM). Welded AA2198 four-stringer panels exhibit a residual strength behaviour superior to that of the flat BM panel. Originality/value – The present study is undertaken on the third-generation airframe-quality Al-Li alloy AA2198 with the main emphasis to investigate the mechanical fracture behaviour of AA2198 BMs, laser beam-welded joints and laser beam-welded integral structures. Studies investigating the damage tolerance of welded integral structures of Al-Li alloys are scarce.

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