Compression Fatigue Response for Carbon Fiber With Conventional and Toughened Epoxy Matrices With Damage

1993 ◽  
Vol 115 (1) ◽  
pp. 116-121 ◽  
Author(s):  
S. R. Swanson ◽  
D. S. Cairns ◽  
M. E. Guyll ◽  
D. Johnson
Keyword(s):  
Carbon Fiber ◽  
Fatigue Loading ◽  
Impact Response ◽  
Matrix System ◽  
Impact Compression ◽  
High Toughness ◽  
Toughened Epoxy ◽  
Compression After Impact ◽  
Open Hole ◽  
Epoxy Matrices

This paper compares the open hole compression, compression after impact, compression fatigue of open hole specimens, and compression fatigue after impact response of quasi-isotropic laminates with IM7 carbon fiber and 3501-6 and 8551-7 epoxy matrices. These matrices can be considered to be a relatively brittle and a high-toughness resin, respectively. The objective was to establish whether the improved compression after impact response associated with high toughness matrices also held after fatigue loading. The results of impact and compression fatigue tests show that residual strengths of the toughened epoxy matrix system were approximately twice that of the brittle matrix system, and that fatigue resistance after impact and of open hole specimens was generally improved.

scholarly journals Evaluation of the survivability of CFRP honeycomb-cored panels in compression after impact tests

2021 ◽  
Vol 15 (56) ◽  
pp. 1-15
Author(s):  
Oleg Staroverov ◽  
Elena Strungar ◽  
Valery Wildemann
Keyword(s):  
Carbon Fiber ◽  
Testing Machine ◽  
Large Cell ◽  
Matrix Cracking ◽  
Homogeneous Deformation ◽  
Compression Tests ◽  
Impact Compression ◽  
Video System ◽  
Compression After Impact ◽  
Fiber Sample

This paper is oriented to the experimental research of the mechanics of the CFRP sandwich plates, glass and carbon fiber sample panels with a large-cell honeycomb core. The method for testing polymer composite sample plates in compression after impact (CAI) tests with joint use of a testing machine and a video system for deformation field registration was tested. Analysis of the experimental data obtained highlighted the impactive sensitivity zone for the test specimens. A quantitative assessment of the load-bearing capacity of glass and carbon fiber sample panels in CAI tests with the different levels of the drop weight impact energy was performed. Photos of samples after impact have been provided. Vic-3D non-contact three-dimensional digital optical system was used to register the displacement and deformation fields on the surface of the samples. The video system was used to evaluate various damage mechanisms, including matrix cracking, delaminations, and rupture of the damaged fibers. The paper studied the evolution of non-homogeneous deformation fields on the surface of the composite samples during the post-impact compression tests and analyzed the configuration of non-homogeneous deformation fields.

Experimental Study on Flexural Fatigue Property of Ultra-High Toughness Cementitious Composites

2010 ◽  
Vol 150-151 ◽  
pp. 1369-1378 ◽  
Author(s):  
Shi Lang Xu ◽  
Wen Liu
Keyword(s):  
Experimental Study ◽  
Fatigue Loading ◽  
Fiber Reinforced Concrete ◽  
Cementitious Composites ◽  
Multiple Cracks ◽  
Steel Fiber Reinforced Concrete ◽  
Flexural Fatigue ◽  
Fatigue Stress ◽  
High Toughness ◽  
Stress Levels

This paper presents an experimental study on the flexural fatigue characteristics of Ultra-High Toughness Cementitious Composites (UHTCC), in contrast with plain concrete and Steel Fiber Reinforced Concrete (SFRC) which have similar compressive strength. The results show that UHTCC improves fatigue life and exhibits a bi-linear fatigue stress-life relationship. The deflection ability, failure characteristics of UHTCC were investigated in the tests. It was observed that, similar to static loading situation, multiple cracks were formed under fatigue loading, while the number of cracks decreased with the degradation of stress levels. For this reason, the deformability is much weaker at lower fatigue stress levels than that at higher stress levels. Moreover, the failure section is divided into three different districts, and the proportion of fiber rupture to fiber pullout is different under different stress levels.

STUDY ON FATIGUE BEHAVIOR OF STRENGTHENED NON-LOAD-CARRYING CRUCIFORM WELDED JOINTS USING CARBON FIBER SHEETS

2012 ◽  
Vol 12 (01) ◽  
pp. 179-194 ◽  
Author(s):  
TAO CHEN ◽  
QIAN-QIAN YU ◽  
XIANG-LIN GU ◽  
XIAO-LING ZHAO
Keyword(s):  
Stress Concentration ◽  
Carbon Fiber ◽  
Welded Joints ◽  
Failure Modes ◽  
Fatigue Behavior ◽  
Local Stress ◽  
Fatigue Loading ◽  
Cfrp Sheets ◽  
Load Carrying ◽  
Weld Toe

This paper reports an experimental study on the use of carbon fiber-reinforced polymer (CFRP) sheets to strengthen non-load-carrying cruciform welded joints subjected to fatigue loading. Failure modes and corresponding fatigue lives were recorded during tests. Scatter of test results was observed. Thereafter, a series of numerical analyses were performed to study the effects of weld toe radius, the number of CFRP layers and Young's modulus of reinforced materials on local stress concentration at a weld toe. It was found that fatigue life of such welded connections can be enhanced because of the reduction of stress concentration caused by CFRP strengthening. Parametric study indicates that the weld toe radius and the amount of CFRP are the key parameters influencing the stress concentration factors and stress ranges of the joint. Enhancement of modulus for adhesive and CFRP sheets can also be beneficial to the fatigue performance to some extent.

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