Impact response of E-glass/epoxy composite bi-directional corrugated core sandwich panels

2020 ◽  
pp. 096739112098275
Author(s):  
A Shahbazi ◽  
A Zeinedini

In this paper, the impact response of bi-directional corrugated core sandwich structures was investigated. The core and skins were made of E-glass/epoxy laminated composites. Additive manufacturing technology was used to print the molds applied to fabricate the cores. The influence of different periods, i.e. T = 30, 37.5, 50 and 75 mm, of the double-cosine corrugated core on the impact response of the panels was evaluated. In addition, some other panels with regular corrugated cores were manufactured to evaluate the impact response of the bi-directional corrugated core structures. A finite element modeling was also carried out to analyze the impact behavior of the samples. The empirical measurements and the numerical predictions showed that the panels with the bi-directional corrugated core have a significant improvement in the absorbed energy under impact loading at each given period. It was also manifested that the panel consisting of the bi-directional corrugated core with T = 37.5 mm has the highest specific energy absorption.

2021 ◽  
pp. 109963622199387
Author(s):  
Mathilde Jean-St-Laurent ◽  
Marie-Laure Dano ◽  
Marie-Josée Potvin

The effect of extreme cold temperatures on the quasi-static indentation and the low velocity impact behavior of woven carbon/epoxy composite sandwich panels with Nomex honeycomb core was investigated. Impact tests were performed at room temperature, –70°C, and –150°C. Two sizes of hemispherical impactor were used combined to three different impactor masses. All the impact tests were performed at the same initial impact velocity. The effect of temperature on the impact behavior is investigated by studying the load history, load-displacement curves and transmitted energy as a function of time curves. Impact damage induced at various temperatures was studied using different non-destructive and destructive techniques. Globally, more damages are induced with impact temperature decreasing. The results also show that the effect of temperature on the impact behavior is function of the impactor size.


Author(s):  
V. Patlolla ◽  
J. George ◽  
Soo-Han Loo ◽  
R. Asmatulu

The purpose of this research was to determine the influence of material properties on the impact response of a laminate, whereby specimens were fabricated and cured under a vacuum and high temperature using three types of pre-impregnated (prepreg), carbon fibers, namely unidirectional fiber, plain weave woven fiber, and non-crimp fiber (NCF). Each carbon fiber panel, usually known for its low-impact properties, of 16 plies underwent impact testing using a low-velocity impactor and visual damage inspection by C-scan in order to measure the damage area and depth, before and after impact testing. These panels were treated with UV exposure and moisture conditioning for 20 days each. Water contact angles were taken into consideration to determine the hydrophobicity and hydrophillicity of the respective prepreg materials. Experimental results and damage analysis showed that UV exposure and moisture conditioning showcased the variation in impact response and behavior, such as load-carrying capacity, absorbed energy, and impact energy of the carbon fiber panels. This study illustrates that non-crimp carbon fiber laminates were far more superior relative to load capacity than woven and unidirectional laminates, with the NCF-AS laminate exhibiting the highest load capacity of 17,244 lb/in (pre-UV) with only 0.89% decrease after UV exposure. This same laminate also had a 1.54% decrease in sustaining impact and 31.4% increase in wettability of the panel. Moreover, the study shows how symmetric and asymmetric stacking sequences affect the impact behavior of non-crimp fiber laminates. These results may be useful for expanding the capacity of carbon fiber, lowering costs, and growing new markets, thus turning carbon fiber into a viable commercial product.


2016 ◽  
Vol 20 (5) ◽  
pp. 531-552 ◽  
Author(s):  
Longquan Liu ◽  
Han Feng ◽  
Huaqing Tang ◽  
Zhongwei Guan

In order to investigate the impact resistance of the Nomex honeycomb sandwich structures skinned with thin fibre reinforced woven fabric composites, both drop-weight experimental work and meso-mechanical finite element modelling were conducted and the corresponding output was compared. Drop-weight impact tests with different impact parameters, including impact energy, impactor mass and facesheets, were carried out on Nomex honeycomb-cored sandwich structures. It was found that the impact resistance and the penetration depth of the Nomex honeycomb sandwich structures were significantly influenced by the impact energy. However, for impact energies that cause full perforation, the impact resistance is characterized with almost the same initial stiffness and peak force. The impactor mass has little influence on the impact response and the perforation force is primarily dependent on the thickness of the facesheet, which generally varies linearly with it. In the numerical simulation, a comprehensive finite element model was developed which considers all the constituent materials of the Nomex honeycomb, i.e. aramid paper, phenolic resin, and the micro-structure of the honeycomb wall. The model was validated against the corresponding experimental results and then further applied to study the effects of various impact angles on the response of the honeycomb. It was found that both the impact resistance and the perforation depth are significantly influenced by the impact angle. The former increases with the obliquity, while the latter decreases with it. The orientation of the Nomex core has little effect on the impact response, while the angle between the impact direction and the fibre direction of the facesheets has a great influence on the impact response.


2008 ◽  
Vol 47-50 ◽  
pp. 612-616 ◽  
Author(s):  
Mehdi Sadeghinia ◽  
Seyyed Mohammad Reza Khalili ◽  
R. Ghadjar

In this paper, the impact behavior of repaired cracked plates was investigated experimentally. single edge cracked aluminum plate having crack length to width ratios of 0.1, 0.3 and 0.5 was repaired with four different patch configurations namely: 3 layer GRP, 5 layer GRP patch, 2/1 FML patch and 3/2 FML patches tested in Charpy impact and the energy absorbed by specimens were compared together and compared with the unrepaired cracked plate. FML patches were made of thin layers of glass/epoxy composites of 0.2 mm thickness with phosphor bronze sheets of 0.2 mm thickness. The patching was single side. The composite and FML patching was more effective in repairing the specimens with greater crack length. Placing 3 GRP and 5 GRP patches increased the absorbed energy by only 3 to 4 joules respectively as compared to unrepaired plate. The use of 2/1 and 3/2 FML patches could increase the absorbed energy two to four times depend on crack length.


2021 ◽  
Vol 15 (57) ◽  
pp. 63-69
Author(s):  
Maria Moreira ◽  
João Carlos Ramos ◽  
Ana Messias ◽  
Maria Augusta Neto ◽  
Ana Paula Amaro ◽  
...  

Up to this moment, there is no guideline regarding the materials to produce mouthguards. The most used is Ethylene-Vinyl Acetate (EVA). Studies indicate that laminating EVA sheets with rigid components could increase the protection capacities of the mouthguards whereas other studies suggest that only replacement of the material within it structure can increase energy absorption. The aim of this work is to evaluate the impact response of four different foils when compared to a 4 mm thickness EVA sheet. Five groups of different materials were subjected to impact tests with energies of 1.72 J, 2.85 J and 4.40 J. In this context was considered the following materials: EVA foils (G1), EVA foils with an EVA foam core (G2), EVA foils with an acetate core (G3), Foils of Erkoloc-pro (G4) and Foils of Ortho IBT resin (G5). Comparisons between the materials were made by qualitative analysis of the average energy-time and load-displacement curves, as well as by comparison of the peak load, maximum displacement, contact time and absorbed energy using the Kruskal-Wallis test. It was possible to conclude that statistically significant differences were found in the energy absorbed (p=0.001). Laminated foils with a soft core (G2) are a good option to produce mouthguards, while EVA foils with an acetate core (G3) and foils of Ortho IBT resin (G5) were declared unsuitable.


Author(s):  
Steven W. Kirkpatrick ◽  
Francisco Gonzalez ◽  
Karl Alexy

There has been significant research in recent years to analyze and improve the impact behavior and puncture resistance of railroad tank cars. Much of this research has been performed using detailed nonlinear finite element analyses supported by full scale impact testing. This use of detailed simulation methodologies has significantly improved our understanding of the tank impact behaviors and puncture prediction. However, the evaluations in these past studies were primarily performed for a few idealized impact scenarios. This paper describes a research program to evaluate railroad tank car puncture behaviors under more general impact conditions. The approach used in this research program was to apply a tank impact and puncture prediction capability using detailed finite element analyses (FEA). The analysis methodologies apply advanced damage and failure models that were validated by series of material tests under various loading conditions. In this study, the analyses were applied to investigate the tank puncture behaviors for a wide range of impact conditions.


Composites ◽  
1995 ◽  
Vol 26 (3) ◽  
pp. 215-222 ◽  
Author(s):  
W.H. Lu ◽  
F.S. Liao ◽  
A.C. Su ◽  
P.W. Kao ◽  
T.J. Hsu

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