Energy absorption in composite stiffeners

International Journal of Crashworthiness

2010

A new crush trigger, called crown trigger, is introduced at one end of carbon-fibre-reinforced polymer circular tubes. Quasistatic compression tests are performed on the tubes to investigate their energy absorption characteristics. It is observed that all tubes are crushed in a brittle fracturing mode. Both crown trigger and bevel trigger can effectively control the position of crushing initiation, reduce the peak load and increase the crushing stability. It is also found that the tube wall of each specimen is delaminated mainly into three layers. The relatively intact exterior layer may constrain the axial splits of the middle layer, make the lamina bundles break off near the base, slow down the central wall crack propagation and thus eliminate a low-performance failure mode. As compared with the bevel trigger, the crown trigger provides nearly the same specific energy absorption but 18.4% lower specific triggering stress and 21.2% higher crushing load efficiency.

Section: Introductionmentioning

confidence: 99%

On a new crush trigger for energy absorption of composite tubes

Huang

International Journal of Crashworthiness

2010

“…The predicted SEAs of half-circle tubes or full-circle tubes are presented in Table 5 and compared to the experimental results. One can see that the varia- (11) tions between predicted and experimental data are less than 5%. These results indicate that the semiempirical analysis method based on the SEAs and boundary effects of quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.…”

Section: Semi-empirical Analysis Methodsmentioning

confidence: 90%

“…The crushing results indicate that the load-displacement curves of flat plates are similar to those of self-supporting composite tubes. Based on the flatplate crush test data obtained by using the NASA fixture, Bolukbasi and Laananen [11] proposed a semi-empirical analysis methodology for predicting the energy absorption capability of the angle and channel composite stiffeners with identical materials, lay-ups, and crush triggers. The predicted results are consistent with the test data.…”

Section: Introductionmentioning

confidence: 99%

Effect of Boundary Conditions on the Energy Absorption of Composite Tubes

Huang¹,

Advanced Composites Letters

2011

Composite tubes with different cross-sectional shapes, including quarter circle, half circle and three-quarter circle, are axially crushed to study the boundary effects on the energy absorption of cylindrical shells and develop a semi-empirical analysis method for the crashworthy design of composite structures. It is observed experimentally that all specimens crush from the chamfered end and exhibit stable progressive crushing with similar macroscopic failure modes. Experimental results indicate that the load-displacement curves of all specimens are similar to those of full-circle tubes. And the quarter-circle tubes show the lowest energy absorption capability, while the half-circle tubes and three-quarter-circle tubes show almost the same energy absorption capability. It is found that quarter-circle thermoset tubes without and with one free edge provide 19% and 13% higher energy absorption capability than the quarter-circle thermoset tubes with two free edges; while quarter-circle thermoplastic tubes without and with one free edge provide 6% and 2% higher energy absorption capability than the quarter-circle thermoplastic tubes with two free edges, respectively. It is also found that the semi-empirical analysis method based on crush data and boundary effects of the quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.

“…Open cross-section specimens, on the other hand, need supporting devices to maintain stability during the crushing process. 16,17 It has been well established that introducing an effective failure initiation site, which triggers progressive failure, is crucial for reducing the initial peak crush load and maximizing energy absorption. Without an effective failure mechanism, composite tubes fail abruptly and catastrophically, with a high initial peak load followed by a very low energy absorption capacity.…”

Section: Introductionmentioning

confidence: 99%

Energy absorption capability of carbon fiber reinforced plastic tubes with semi-circle grooved external trigger

Yan

Journal of Reinforced Plastics and Composites

et al. 2016

For the purpose of improving the energy absorption performance of capped carbon fiber reinforced plastic tubes, a semi-circle grooved crush-cap is proposed and a series of experiments and improvements has been conducted. Tubes, which are respectively built by carbon fiber laminate and carbon fiber woven cloth, with semi-circle grooved crush-caps, combined (notched-end and crush-cap) failure mechanisms were investigated to identify the optimal configuration that would result in the most stable initial peak load while providing the highest possible specific energy absorption. Experimental results show that the new crush-caps lower the initial load, effectively yielding a high specific energy absorption. These results are significantly influenced by the semi-circle radii of the crush-caps. Furthermore, two failure modes have been observed in tests by changing the external trigger and tube material. The failure mode changes from splaying mode to fragmentation mode with the decrease of radii. The combined failure triggers proved the reduction in the initial load without smoothing the load-displacement curve, therefore, they reduce the energy absorption capability of carbon fiber reinforced plastic tubes. In our experiments, the tested tube which is made by T300/5208 woven cloth with R3 trigger is ground into powder, resulting in an specific energy absorption as high as 101.7 kJ/kg also with a smooth load-displacement curve.