An effective peak stress formula for concrete confined with carbon fiber reinforced plastics

2003 ◽  
Vol 30 (5) ◽  
pp. 882-889 ◽  
Author(s):  
Chih-Tsung Lin ◽  
Yeou-Fong Li
Keyword(s):  
Carbon Fiber ◽  
Peak Stress ◽  
Confined Concrete ◽  
Test Results ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Concrete Cylinders ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced

The uniaxial compression test results of three different strengths and three different sizes of concrete cylinders confined with different layers of carbon fiber reinforced plastics (CFRP) are used to develop an effective peak stress formula for predicting the strength of confined concrete. The theory of this peak stress formula was based on the triaxial confined test of soil and rock, and the lateral confinement of the concrete was assumed to be due to the CFRP. The peak stress of the confined concrete can be explicitly expressed as a function of the unconfined concrete strength and the lateral CFRP confined strength. Experiments were done on 108 concrete cylinders, and the test results show the accuracy and effectiveness of this peak stress formulation of confined concrete.Key words: confined concrete, peak stress, carbon fiber reinforced plastics.

INCREASING SENSITIVITY OF EDDY CURRENT NON-DESTRUCTIVE TESTING OF DELAMINATION IN CARBON-FIBER REINFORCED PLASTICS

2021 ◽  
pp. 28-37
Author(s):  
P. N. Shkatov ◽  
G. A. Didin ◽  
A. A. Ermolaev
Keyword(s):  
Carbon Fiber ◽  
Eddy Current ◽  
Calculation Model ◽  
Fiber Reinforced ◽  
Destructive Testing ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced ◽  
The Difference

The paper is concerned with increasing sensitivity of eddy current nondestructive testing of most dangerous delamination in carbon-fiber reinforced plastics (CFRP). Increased sensitivity is achieved by separate registration and comparison of eddy current signals obtained from a set of stratifications of carbon fibers with the same orientation. The separation of eddy current signals is possible due to pronounced anisotropy of the electrical conductivity of the layers dominant in the direction of the fibers of the corresponding layer. Eddy-current signals are registered by eddy current probes with maximum sensitivity in a given angular direction. Prior to the scan eddy current signals of the probe are leveled on a defect-free area. The influence of the working gap on the difference between the eddy current signals of the probe is suppressed by normalizing it according to one of the signals. The analysis of the registered signals from delamination has been performed using an approximate calculation model. The reliability of the obtained results has been confirmed by comparison with experimental results and calculations using the finite element method.

Rotary Ultrasonic Machining: Effects of Tool End Angle on Delamination of CFRP Drilling

2017 ◽  
Author(s):  
Palamandadige K. S. C. Fernando ◽  
Meng (Peter) Zhang ◽  
Zhijian Pei ◽  
Weilong Cong
Keyword(s):  
Carbon Fiber ◽  
Material Removal ◽  
Ultrasonic Machining ◽  
Fiber Reinforced ◽  
Rotary Ultrasonic Machining ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Hole Making ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced

Aerospace, automotive and sporting goods manufacturing industries have more interest on carbon fiber reinforced plastics due to its superior properties, such as lower density than aluminum; higher strength than high-strength metals; higher stiffness than titanium etc. Rotary ultrasonic machining is a hybrid machining process that combines the material removal mechanisms of diamond abrasive grinding and ultrasonic machining. Hole-making is the most common machining operation done on carbon fiber reinforced plastics, where delamination is a major issue. Delamination reduces structural integrity and increases assembly tolerance, which leads to rejection of a part or a component. Comparatively, rotary ultrasonic machining has been successfully applied to hole-making in carbon fiber reinforced plastics. As reported in the literature, rotary ultrasonic machining is superior to twist drilling of carbon fiber reinforced plastics in six aspects: cutting force, torque, surface roughness, delamination, tool life, and material removal rate. This paper investigates the effects of tool end angle on delamination in rotary ultrasonic machining of carbon fiber reinforced plastics. Several investigators have cited thrust force as a major cause for delamination. Eventhogh, it is found on this investigation, tool end angle has more significant influence on the delamination in rotary ultrasonic machining of carbon fiber reinforced plastics comparing to cutting force and torque.

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