A new device for determining the compression after impact strength in thin laminates

Abstract

Abstract:In this work a new device has been developed to estimate compression-after-impact (CAI) strength. This device allows the testing of laminates thinner than those recommended by CAI test standards. The pro-posed device is composed of a support structure, with a set of vertical ribs that stabilize the specimen during the test, increasing the buckling load. A numerical analysis was made to ensure that global buck-ling does not occur in the laminate during the CAI test, and that there is no interference with the damage area. Laminate specimens were tested with the proposed device and the ASTM device. For specimens 4.416 mm thick (thickness according to ASTM D7137 standard), the test results were similar with both devices. For thinner laminates, higher CAI strength was estimated with the proposed device than with the ASTM device, showing that the global buckling was delayed.

Failure mechanisms and damage evolution of laminated composites under compression after impact (CAI): Experimental and numerical study

“…CAI failure mechanisms during local instability and at the moment of structural failure are thus still not fully understood. Under uniaxial compression, the buckling and failure behaviour of laminated composites with impact damage are strongly influenced by impact damage extent [12][13][14][15][16] and specimen geometric parameters [6,17,18] for a given material system. Amaro et al [19] performed compression tests on crossply laminates containing different damage amounts, and showed three different buckling failure modes: pure local buckling, pure global buckling and combined local and global buckling.…”

Correlation between Drop Impact Energy and Residual Compressive Strength According to the Lamination of CFRP with EVA Sheets

“…For the CAI test, the temperature distribution was monitored using a thermal imaging camera. For temperature results, the maximum temperature at the time of breakage at room temperature was derived for comparative analysis [15][16][17][18][19].…”

The effect interleaving has on thin-ply non-crimp fabric laminate impact response: X-ray tomography investigation

“…All the impacted coupons displayed the same failure mechanisms, local buckling at the impact site followed by damage propagation perpendicular to the applied load (Figure 13a). In contrast, the pristine samples presented through-the-width damage localized at the topmost clamping region, suggesting that global buckling occurred during compression [28]. Consequently, the CAI results of pristine specimens are considered to be of a lower strength threshold.…”

“…(Figure 1a) was manufactured. This fixture enabled the testing of laminates thinner than those recommended by the standard ASTM 7137/D7137M [22], which would otherwise fail by structural global buckling [28][29][30]. It consisted of two anti-buckling plates with equally spaced vertical ribs to stabilize the specimen on the vertical plane.…”