Failure Mechanism and Energy Damage Evolution of Deep Sandstone Anchored by Carbon Fiber

Author(s):  
Lei Chen ◽  
Pingping Lu ◽  
Shuguang Zhang
2021 ◽  
Vol 28 (1) ◽  
pp. 139-152
Author(s):  
Teng Huang ◽  
Dongdong Zhang ◽  
Yaxin Huang ◽  
Chengfei Fan ◽  
Yuan Lin ◽  
...  

Abstract In this study, the flexural bearing capacity and failure mechanism of carbon fiber-reinforced aluminum laminate (CARALL) beams with a double-channel cross-section and a 3/2 laminated configuration were experimentally and numerically studied. Two types of specimens using different carbon fiber layup configurations ([0°/90°/0°]3 and [45°/0°/−45°]3) were fabricated using the pressure molding thermal curing forming process. The double-channel CARALL beams were subjected to static three-point bending tests to determine their failure behaviors in terms of ultimate bearing capacity and failure modes. Owing to the shortcomings of the two-dimensional Hashin failure criterion, the user-defined FORTRAN subroutine VUMAT suitable for the ABAQUS/Explicit solver and an analysis algorithm were established to obtain a progressive damage prediction of the CFRP layer using the three-dimensional Hashin failure criterion. Various failure behaviors and mechanisms of the CARALL beams were numerically analyzed. The results indicated that the numerical simulation was consistent with the experimental results for the ultimate bearing capacity and final failure modes, and the failure process of the double-channel CARALL beams could be revealed. The ultimate failure modes of both types of double-channel CARALL beams were local buckling deformation at the intersection of the upper flange and web near the concentrated loading position, which was mainly caused by the delamination failure among different unidirectional plates, tension and compression failure of the matrix, and shear failure of the fiber layers. The ability of each fiber layer to resist damage decreased in the order of 90° fiber layer > 0° fiber layer > 45° fiber layer. Thus, it is suggested that 90°, 0°, and 45° fiber layers should be stacked for double-channel CARALL beams.


2006 ◽  
Vol 33 (11) ◽  
pp. 1438-1449 ◽  
Author(s):  
Ayman S Kamel ◽  
Alaa E Elwi ◽  
Roger J.J Cheng

This paper presents a study on the interfacial behavior of carbon fiber reinforced polymer (CFRP) sheets when applied to concrete members as external reinforcement. Two bond test methods that are detailed in the paper were used in separate test series to study the bond behavior and failure mechanism of CFRP sheets bonded to concrete. A modified push-apart test method was proposed and tested. It was concluded that there existed an effective length beyond which there will be no increase in the ultimate capacity of the joint. An experimental test method to determine the effective bond length was also proposed and tested. The strains at the edge of the CFRP sheets are consistently higher than those at the center. The anchorage requirements for the CFRP sheets were also investigated in this study. Anchor sheets placed at 90° to the primary test sheets and bonded underneath the tested sheet showed better or equivalent overall bond behavior compared with those bonded on top of the tested sheet. The distance at which the anchor sheet is placed from the crack does not appear to change the bond behavior.Key words: bond, concrete, debonding, failure mechanism, carbon fiber reinforced polymer (CFRP) sheets, anchor sheets.


Author(s):  
Chunhua Ren ◽  
Xiaochuan Zhang ◽  
Hongwei Ji ◽  
Huaiwen Wang ◽  
Sumit. Hazra ◽  
...  

2021 ◽  
Author(s):  
Karmanya Ratra

Carbon fiber bicycle wheels were tested under low velocity impact to monitor the damage evolution of the impact event. A wheel model designed by KQS Inc. (industrial partner) with eight different configurations, including spoke tension, number of spokes, and location of impact on the rim were investigated. IR thermography combined with PCA was used to monitor the damage during impact. Results showed that wheels in line with spokes had 16% higher impact energy absorption compared to those impacted in between spokes on average (58.9 J vs 70.2 J). The 20 spoked wheels had a slightly higher (6%) impact energy absorption than the 24 spoked wheels. The added stiffness due to the extra spokes reduced the impact energy absorption of rim. Wheels with higher spoke tension also had slightly improved impact energy absorption (4%). The test protocol established in this study provides a good understanding of the wheel’s impact damage evolution.


2021 ◽  
Author(s):  
AADITYA SURATKAR ◽  
JOHN MONTESANO ◽  
JEFFREY WOOD

An experimental study was performed to characterize the evolution of damage in a unidirectional Non-Crimp Fabric (NCF) carbon fiber/snap-cure epoxy composite under in-plane quasi-static tensile loads. The NCF composites were manufactured using a High Pressure-Resin Transfer Molding (HP-RTM) process and comprised a fast-curing epoxy resin and heavy tow unidirectional carbon fiber NCF layers. Laminates with stacking sequences [0/±45/90] and [±45/0 ] were subjected to axial and transverse quasi-static tensile loads and an in-situ Edge replication (ER) technique was used to capture the damage evolution at predefined intervals. An imprint of the composite microstructure, as observed on the edges of a test coupon, was created on a cellulose acetate replicating tape, which was then observed under the microscope. The onset and progression of ply cracks and delamination, which were the two major damage modes present, were quantified and correlated with the stress-strain curves and changes in stiffness. The influence of stacking sequence and ply thickness are also captured.


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