Impact Damage Effects on the Strength of Advanced Composites

Composite materials usage in several industrial fields is now widespread, and this leads to the necessity of overcoming issues that are still currently open. In the aeronautic industry, this is especially true for Barely Visible Impact Damage (BVID) and humidity uptake issues. BVID is the most insidious kind of impact damage, being rather common and not easily detectable. These, along with the ageing that a composite structure could face during its operative life, could be a cause of fatal failures. In this paper, the influence of water absorption on impacted specimens compressive residual strength was studied. Specimens were impacted using a modified Charpy pendulum. Two different locations were chosen for comparison: Near-Edge (NE) and Central (CI). Accelerated hygrothermal ageing was conducted on impacted and reference nonimpacted coupons, placing them in a water-filled jar at 70 °C. Compressive tests were performed in accordance with the Combined Loading Compression (CLC) test method. A Dynamic Mechanical Analysis (DMA) was performed as well. The results showed the influence of hygrothermal ageing, as expected. Nevertheless, the influence of impact location on compressive residual strength is not clearly noticeable in aged specimens, leading to the conclusion that hygrothermal ageing may have a greater effect on composite compressive strength than the analysed BVI damage.

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Experimental and analytical assessment of the hypervelocity impact damage of GLAss fiber REinforced aluminum

Defence Technology ◽

10.1016/j.dt.2021.05.018 ◽

2021 ◽

Author(s):

Md Zahid Hasan

Keyword(s):

Glass Fiber ◽

Impact Damage ◽

Hypervelocity Impact ◽

Fiber Reinforced ◽

Glass Fiber Reinforced ◽

Analytical Assessment

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Numerical Investigation on the Ultimate Strength of Box Beams with Impact Damage

Journal of Marine Science and Application ◽

10.1007/s11804-020-00177-9 ◽

2020 ◽

Author(s):

Wei Xu ◽

C. Guedes Soares

Keyword(s):

Residual Stress ◽

Ultimate Strength ◽

Impact Damage ◽

Ship Hulls ◽

Four Point Bending ◽

Impact Location ◽

Box Beam ◽

Box Beams ◽

Fracture Damage ◽

The Impact

AbstractThe objective of this paper is to study the residual ultimate strength of box beams with impact-induced damage, as a model of what may occur in ship hulls. The bottom and side plates of ship hulls can suffer denting or fracture damage due to grounding, collision and other contacts during the ship’s service life and these impact-induced damages could result in considerable strength degradation. Box beams are firstly subjected to impact loading and then four-point bending loading is imposed on the damaged structures to assess the residual strength using ANSYS/LS_DYNA. The ultimate moment and collapse modes are discussed considering the effect of impact location. The impact-induced deformation is introduced in the four-point bending simulation, and the impact-induced stress is included or not to determine the effect of residual stress and distortion after impact. It is shown that impact location has significant influence on the residual ultimate bending moment of the damaged box beam providing that the impact energy is kept constant. The collapse modes also change when the impactor strikes on different locations. Damaged hard corner and inclined neutral axes might explain the reduction of ultimate strength and diverse collapse modes. The residual stress in the box beam after impact may increase or decrease the ultimate strength depending on impact location.

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