Comparison of bevel and tulip triggered pultruded tubes for energy absorption

Abstract

The crushing behavior of E-glass~polyester and E-glass/vinyl ester pultruded tubes has been found to be significantly different for tulip triggered specimens as compared with bevel triggered specimens. Up to 100% more energy per unit weight was absorbed by tulip triggered tubes. In addition, the crushing was more controlled and predictable with the tulip trigger. The morphology of the material in the crushing zone differed in the amount and the pattern of fracture. The fracture pattern and crushing behavior initiated by both triggers were foundnot to change during crushing. The difference in crushing appeared to arise from the different abilities of the tubes to support load because of the different geometry of individual load-carrying structures that resulted from triggering.

On a new crush trigger for energy absorption of composite tubes

“…(2) delamination or inter-laminar crack growth, Mode II fracture; (3) axial splitting of the middle layer; (4) lamina bundle bending damage and fracture; (5) friction between the platen and the crush zone; (6) friction between the debris wedge and the interior layer; (7) friction between the debris wedge and the middle layer; (8) friction between the middle layer and the exterior layer; and (9) friction between adjacent lamina due to sliding.…”

“…Similar to single-chamfer-triggered pattern, applying this trigger pattern is an efficient way to weaken the peak load, reduce the probability of catastrophic failure and avoid unstable crush. Thornton, Czaplicki and Robertson [8,25] have found that the tulip trigger, incorporated at one end of the square tubes, affords an improvement in the crush stability and nearly 100% increase of the specific energy absorption (SEA) as compared with the bevel trigger. An inner-type jig [28] progressive crushing mode and improve the energy absorption capability.…”

“…The tests have also indicated that the energy absorption mechanism of composites is far more complex than those observed in metallic materials, including matrix cracking, matrix crushing, fibre breakage, fibre buckling, delamination and fibre-matrix de-bonding [2,4,11]. The energy absorption characteristics of composite components rely not only on the intrinsic properties of the materials, such as fibre type, matrix type, fibre architecture, fibre content, lamina design and fibre surface treatment [19,21], but also on the crush triggers [6,8,9,[12][13][14][15][16]20,[23][24][25][26][27][28][29] incorporated at appropriate locations in the components to initiate a stable progressive crush in a controlled manner without causing unacceptably high values of peak load or catastrophic failures.…”

Non-Axial Crushing of E-Glass/Polyester Pultruded Tubes

“…Axial crushing of E-glass/polyester tubes and E-glass/vinyl ester tubes [11] has shown that certain parameters must be controlled for crushing to proceed satisfactorily. Of primary importance is the control of crack behavior.…”

Progressive Crushing of Polymer Matrix Composite Tubular Structures: Review

“…Rabiee, H. Ghasemnejad graphite/epoxy and Kevlar/epoxy square cross section tubes. Czaplicki et al [85] reported that significantly higher energy absorption of tulip-triggered specimens were observed compared to bevel triggered specimens of the same geometry and material.…”