Experimental Investigation of the Influence of Stacking Sequence and Delamination Size on the Natural Frequencies of Delaminated Composite Plate

Author(s):  
Muhammad Imran ◽  
Rafiullah Khan ◽  
Saeed Badshah

The vibration properties of the composite structures is critical to the reliability and durability of the structures. Vibration becomes worst in case the delamination is present within laminates. In this research work, experimental, finite element and analytical techniques have been applied in order to analyze the influence of stacking sequence and delamination sizes on the natural frequencies of carbon fiber reinforced polymer composite (CFRP) plate with and without delamination. The boundary conditions in this research work was (SSSS) (all sides simply supported. Experiments were performed to study the vibration characteristics of (CFRP) delaminated composite plate. Software package ABQUS was used to model and analyze the vibration response of carbon fiber reinforced polymer composite plate for (SSSS) boundary condition and the effect of stacking sequence and delamination size was calculated. Rayleigh- Ritz Method was used to find the natural frequencies for different delamination sizes and stacking sequences. The results was concluded that natural frequencies were significantly affected by the delamination sizes and stacking sequences. Stacking sequence of (0/90/45/90) showed higher values of natural frequencies in lower mode subjected to all-sides simply supported boundary conditions. It was interesting to see that there were small differences in values of natural frequencies among the stacking sequences for lower modes but the difference gradually increased in case of higher modes.    

2013 ◽  
Vol 689 ◽  
pp. 353-357
Author(s):  
Chong Xi Bai ◽  
Xin Yan Shao ◽  
Qiu Ping Wang

The law of stress increment of unbonded carbon fiber reinforced polymer (CFRP) tendons at service stage and flexural load bearing capacity limit state is unclear, so it is difficult to accurately calculate crack width, deflection and load bearing capacity. In order to calculate the stress of CFRP tendons, deformation compatibility condition and moment-curvature analysis method are used to compile nonlinear full-range analysis programs of simply supported concrete beam partially prestressed with unbonded CFRP tendons. The computing results of stress in CFRP tendons are in good agreement with the tested results as a whole, so it indicates that the simulation analysis programs are reliable.


2016 ◽  
Vol 866 ◽  
pp. 114-118
Author(s):  
Mary Ann N. Ahalajal ◽  
Nathaniel C. Tarranza

This study investigates the use of carbon fiber reinforced polymer (CFRP) strips as an alternative way of retrofitting steel I-beams. The flexural strength and maximum deflection of unstrengthened and CFRP-strengthened steel I-beams were compared. Three groups of samples were studied: the first group has CFRP strip installed on the tension flange of the steel I-beam; the second group has CFRP strips installed on the compression and tension flanges of the steel I-beam; and the third group comprises unstrengthened steel I-beams which serve as control specimens. All specimens were tested as simply supported beams under third-point loading. A reaction frame machine was used to apply the load while a dial indicator was used to measure deflections.


2019 ◽  
Vol 7 (1) ◽  
pp. 30-34
Author(s):  
A. Ajwad ◽  
U. Ilyas ◽  
N. Khadim ◽  
Abdullah ◽  
M.U. Rashid ◽  
...  

Carbon fiber reinforced polymer (CFRP) strips are widely used all over the globe as a repair and strengthening material for concrete elements. This paper looks at comparison of numerous methods to rehabilitate concrete beams with the use of CFRP sheet strips. This research work consists of 4 under-reinforced, properly cured RCC beams under two point loading test. One beam was loaded till failure, which was considered the control beam for comparison. Other 3 beams were load till the appearance of initial crack, which normally occurred at third-quarters of failure load and then repaired with different ratios and design of CFRP sheet strips. Afterwards, the repaired beams were loaded again till failure and the results were compared with control beam. Deflections and ultimate load were noted for all concrete beams. It was found out the use of CFRP sheet strips did increase the maximum load bearing capacity of cracked beams, although their behavior was more brittle as compared with control beam.


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