The impact resistance of composite materials — a review

https://cyberleninka.org/article/n/663976.pdf

A categorical framework of manufacturing for industry 4.0 and beyond

A review of experimental data and elementary theoretical formulas for compressive failure of polymer matrix fibre composites indicates that the dominant failure mode is by plastic kinking. Initial local fibre misalignment plays a central role in the plastic kinking process. Theoretical analyses and numerical results for compressive kinking are presented, encompassing effects of strain-hardening, kink inclination, and applied shear stress. The assumption of rigid fibres is assessed critically, and the legitimacy of its use for polymer matrix composites is established.

http://www-mech.eng.cam.ac.uk/profiles/fleck/papers/38.pdf

Compressive failure of fibre composites

One dimensional modelling of failure in laminated plates by delamination buckling

A review of the recent developments in the analysis of laminated beams and plates with an emphasis on shear effects and buckling is presented. A discussion of various shear-deformation theories for plates and beams is given. The available theories are derived assuming a variation of either the in-plane displacement components or the stress components or both in the thickness coordinate. A review of the recently developed finite elements to analyze thin and thick laminated beams and plates is given next. These elements have been derived using the displacement methods, or the mixed methods or the hybrid methods. Recent studies on the buckling and postbuckling behavior of perfect and geometrically imperfect plates are described next. These behaviors have been studied using analytical, numerical, and experimental techniques. Finally, a review of the various studies on the delamination buckling and growth in beams and plates is given. Once again, the studies have been conducted using analytical, numerical, and experimental techniques. The energy release rates have been determined using closed-form solutions or using numerical differentiation. Mention also is made of studies on multiple delaminations and on dynamic response of composite laminates under impact loads.

Recent advances in analysis of laminated beams and plates. Part I - Sheareffects and buckling.

An experimental investigation has been conducted to determine the effect of low-velocity impact damage and unloaded circular holes on the compressive strength of a 48-ply orthotropic graphite/epoxy flat laminate. Specimens were impacted by a 1.27-cm-diameter aluminum sphere with speeds from 52 to 101 m/x to simulate momenta typical of low-velocity impact hazards that can occur in commercial aircraft service. It is shown that low-velocity impact damage can significantly degrade the static compressive strength of the laminate. Specimens that fail at axial strains above 0.008 in the undamaged condition can fail at strains as low as 0.0031 when impacted at 100 m/s. Circular holes also reduce the static compressive strength of the laminate. The failure strain decreases as the hole diameter increases.

Effect of Impact Damage and Holes on the Compressive Strength of a Graphite/Epoxy Laminate

An experimental study was conducted to evaluate the effect of laminate orthotropic properties and panel width on the compression strength of 48-ply graphite-epoxy laminates with drilled holes. The test results were evaluated on the basis of hole size and specimen width and were used to determine parameters necessary to predict trends using the point-stress failure criterion. Good agreement was obtained between experimental and predicted values of failure for panels fabricated from two quasi-isotropic laminates and one orthotropic laminate. The results indicate that panels of different widths that have large holes in relation to the failure prediction parameter should be included in any test program conducted to develop predictions. Panel failures are shown to have an upper limit given by the reduction in specimen cross-sectional area and a lower limit given by the effect of stress concentration. Limited tests of a quasi-isotropic laminate were conducted on panels with machined cracks and panels with punched holes and the results compared to those with drilled holes. The sequence of events that occurs in the vicinity of a hole during failure was identified and provides insight into the mechanisms associated with failure. a d

Effects of Orthotropy and Width on the Compression Strength of Graphite-Epoxy Panels with Holes

Structural technology of laminated filamentary-composite stiffened-panel structures under combined in-plane and lateral loadings is discussed. Attention is focused on (1) methods for analyzing the behavior of these structures under load and for determining appropriate structural proportions for weight efficient configurations, and (2) effects of impact damage and geometric imperfections on structural performance. Recent improvements in buckling analysis involving combined in-plane compression and shear loadings and transverse shear deformations are presented. A computer code is described for proportioning or sizing laminate layers and cross-sectional dimensions, and the code is used to develop structural efficiency data for a variety of configurations, loading conditions, and constraint conditions. Experimental data on buckling of panels under in-plane compression is presented to validate the analysis and sizing methods and to illustrate structural performance and efficiency obtained from representative structures. Experimental results show that strength of panels under in-plane compression can be degraded by low-velocity impact damage. Mechanisms of impact-damage initiation and propagation are described. Finally, data are presented that indicates the matrix is a significant factor influencing tolerance to impact damage.

/pdf/recent-developments-in-the-design-testing-and-impact-damage-t2nuq69wwk.pdf

Recent Developments in the Design, Testing and Impact-Damage Tolerance of Stiffened Composite Panels

An experimental investigation was conducted to identify the failure mechanisms and to understand damage propagation in compression-loaded composite structures. The tests were conducted on several laminates of different ply orientation with thickness that ranged from 0.56 to 0.75 cm. The panels were damaged by 1.27-cm-diameter aluminum spheres propelled normal to the specimen surface at velocities ranging from 30 m/s to 140 m/s. Results indicate that there is significant internal laminate damage due to low-velocity impact with no surface damage. The internal damage consists of delamination and intraply cracking. Three damage propagation modes were identified as causing specimen failure; which are delamination, axial load-lateral deformation coupling, and local shear failure.

Low-velocity impact damage in graphite-fiber reinforced epoxy laminates

Low velocity impact damage on the compressive strength of graphite/epoxy hat stiffened panels is studied. Fourteen panels, representative of minimum-mass designs for two compression load levels were tested. Eight panels were damaged by impact and the effect on compressive strength was evaluated by comparing the results with data for undamaged panels. The impact tests consisted of firing 1.27 cm diameter aluminum projectiles normal to the plane of the panel at a velocity of approximately 55 m/sec to simulate impact from runway debris. The results of this investigation indicate that impact damage in the panels designed for 0.53 MN/m was contained locally and the damaged panels were capable of carrying the design load. The panels designed for 1.58 MN/m failed between 50 and 58 percent of the design load due to impact damage in the high axial stiffness region. The extent of damage in the high axial stiffness region of both panel designs increased with the magnitude of applied axial load. Damage in this region was the most significant factor in reducing panel strength. Limited damage that was not visually detectable reduced ultimate strength as much as extensive visible damage.

/pdf/effect-of-low-velocity-impact-damage-on-the-compressive-hhbkiwm1qw.pdf

Marvin D. Rhodes

Papers

Effect of Impact Damage and Holes on the Compressive Strength of a Graphite/Epoxy Laminate

Effects of Orthotropy and Width on the Compression Strength of Graphite-Epoxy Panels with Holes

Recent Developments in the Design, Testing and Impact-Damage Tolerance of Stiffened Composite Panels

Low-velocity impact damage in graphite-fiber reinforced epoxy laminates

Effect of Low Velocity Impact Damage on the Compressive Strength of Graphite/Epoxy Hat-Stiffened Panels