scholarly journals Design, Manufacturing, and Characterization of Hybrid Carbon/Hemp Sandwich Panels

2021 ◽  
Author(s):  
Luca Boccarusso ◽  
Fulvio Pinto ◽  
Stefano Cuomo ◽  
Dario De Fazio ◽  
Kostas Myronidis ◽  
...  
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Industrial Applications ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Continuous Manufacturing ◽  
Low Velocity ◽  
Impact Compression

AbstractAdvanced sandwich composite structures that incorporate foams or honeycombs as core materials, have been extensively investigated and used in various applications. One of the major limitations of the conventional materials used is their weak impact resistance and their end-of-life recyclability and overall sustainability. This paper is focused on the study of the production and mechanical characterization of hybrid sandwich panels using hemp bi-grid cores that were manufactured with an ad hoc continuous manufacturing process. Bi-grid structures were stratified in multiple layers, resulting in cores with different thicknesses and planar density. Sandwich panels made with carbon fibers skins were then subjected to Low Velocity Impact, compression and indentation and the damaged panels were investigated via CT-Scan. Results show that the high tailorability of the failure modes and the very good energy absorption properties of the hybrid material open new exciting perspectives for the development of new sandwich structures that can extend the use of natural fibers into several industrial applications.

Low-velocity impact response of wood-strand sandwich panels and their components

Holzforschung ◽  
2018 ◽  
Vol 72 (8) ◽  
pp. 681-689 ◽  
Author(s):  
Mostafa Mohammadabadi ◽  
Vikram Yadama ◽  
LiHong Yao ◽  
Debes Bhattacharyya
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Low Velocity Impact ◽  
Insulation Material ◽  
Low Velocity ◽  
Velocity Impact ◽  
Section Modulus ◽  
The Impact

AbstractProfiled hollow core sandwich panels (SPs) and their components (outer layers and core) were manufactured with ponderosa and lodgepole pine wood strands to determine the effects of low-velocity impact forces and to observe their energy absorption (EA) capacities and failure modes. An instrumented drop weight impact system was applied and the tests were performed by releasing the impact head from 500 mm for all the specimens while the impactors (IMPs) were equipped with hemispherical and flat head cylindrical heads. SPs with cavities filled with a rigid foam insulation material (SPfoam) were also tested to understand the change in EA behavior and failure mode. Failure modes induced by both IMPs to SPs were found to be splitting, perforating, penetrating, core crushing and debonding between the core and the outer layers. SPfoams absorbed 26% more energy than unfilled SPs. SPfoams with urethane foam suffer less severe failure modes than SPs. SPs in a ridge-loading configuration absorbed more impact energy than those in a valley-loading configuration, especially when impacted by a hemispherical IMP. Based on the results, it is evident that sandwich structure is more efficient than a solid panel concerning impact energy absorption, primarily due to a larger elastic section modulus of the core’s corrugated geometry.

Compression after impact behavior of titanium honeycomb sandwich structures

2017 ◽  
Vol 20 (5) ◽  
pp. 639-657 ◽  
Author(s):  
Wei Zhao ◽  
Zonghong Xie ◽  
Xiang Li ◽  
Xishan Yue ◽  
Junfeng Sun
Keyword(s):  
Failure Modes ◽  
Sandwich Structures ◽  
Impact Damage ◽  
Sandwich Panels ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Failure Strength ◽  
Compressive Failure ◽  
Low Velocity ◽  
Honeycomb Sandwich

Titanium honeycomb sandwich structures are gradually used in several newly developed aircrafts in China. During the manufacturing process and aircraft service life, low-velocity impacts from foreign objects (typically stones, tools and hails, etc.), would quite likely happen and could not be completely avoided. In order to evaluate the influence of low-velocity impact damage on titanium honeycomb sandwich structures, unidirectional in-plane compression tests on both intact and impact damaged sandwich panels were conducted to obtain their failure modes and compressive failure strength. Test results showed that the low-velocity impact damage could cause the change in failure modes and a 9% to 15% decrease in the compressive failure strength. Different impact energy levels showed a limited influence on the compressive failure strength. Numerical analysis was conducted to study the compression after impact behavior of titanium sandwich panels. Parametric finite element models that contained all the geometric and the structural details of honeycomb core cells, as well as the indentation and the crushed core region, were developed in the analysis. The numerical results successfully exhibited the failure process of the intact and impact damaged titanium sandwich panels subjected to unidirectional in-plane compression, similar to what observed in the tests. The predicted compressive failure strength also agreed very well with the test data.

scholarly journals An Investigation on Low Velocity Impact Response of Multilayer Sandwich Composite Structures

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
S. Jedari Salami ◽  
M. Sadighi ◽  
M. Shakeri ◽  
M. Moeinfar
Keyword(s):  
Composite Structures ◽  
Sandwich Panel ◽  
Testing Machine ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Core Material ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Core

The effects of adding an extra layer within a sandwich panel and two different core types in top and bottom cores on low velocity impact loadings are studied experimentally in this paper. The panel includes polymer composite laminated sheets for faces and the internal laminated sheet called extra layer sheet, and two types of crushable foams are selected as the core material. Low velocity impact tests were carried out by drop hammer testing machine to the clamped multilayer sandwich panels with expanded polypropylene (EPP) and polyurethane rigid (PUR) in the top and bottom cores. Local displacement of the top core, contact force and deflection of the sandwich panel were obtained for different locations of the internal sheet; meanwhile the EPP and PUR were used in the top and bottom cores alternatively. It was found that the core material type has made significant role in improving the sandwich panel’s behavior compared with the effect of extra layer location.

scholarly journals Fabrication and low-velocity impact response of pyramidal lattice stitched foam sandwich composites

2020 ◽  
Vol 27 (1) ◽  
pp. 245-257
Author(s):  
Jiale Jia ◽  
Shi Yan
Keyword(s):  
Numerical Simulation ◽  
Failure Modes ◽  
Absorption Capacity ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Foam Core ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact

AbstractIn this study, the foam sandwich panels were manufactured by integrating top facesheet and bottom facesheet with pyramidal lattice stitched core to overcome the weak interface between the core and skins of the sandwich structures. Low-velocity impact test and numerical simulation were conducted to reveal the failure mechanisms and energy absorption capacity at sandwich composite with foam core, different strut stitched foam core under different impact energy. The experimental results show showed that the strut core can improve the impact resistance of the specimen, and which is closely related to the diameter of the strut core. Compared with foam sandwich structure, pyramidal lattice stitched foam sandwich composites have comparable specific energy absorptions. The failure modes were also analyzed which is: fiber breakage, delamination, foam deformation and strut core breakage. The research presented here confirms that numerical simulation show good agreement with the experiment.

scholarly journals Impact Resistance of Fibre Reinforced Composite Railway Freight Tank Wagons

2021 ◽  
Vol 5 (6) ◽  
pp. 152
Author(s):  
George Edward Street ◽  
Preetum Jayantilal Mistry ◽  
Michael Sylvester Johnson
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Biaxial Loading ◽  
Impact Damage ◽  
Impact Resistance ◽  
Matrix Cracking ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Fibre Direction ◽  
Reinforced Composite

The use of fibre reinforced composite materials is one method by which the lightweighting of rail vehicles can be achieved. However, the issue of impact damage, amongst other challenges, limits their safety certification. This issue is accentuated by the high levels of loading a rail vehicle may be subjected to during service. This paper addresses the significance of pre-tension on large composite structures, specifically for a composite redesign of a pressure vessel for a freight tank wagon. Preloading was determined to be detrimental to the overall impact resistance of a large composite vessel. At 15.71 J of impact energy, there was a 22% increase in mean absorbed energy for a uniaxially loaded panel over an unloaded panel. However, there was only a 4% difference in penetration depth between uniaxial and biaxial loading. A novel finding from these results is that the effects of preloading are more profound if the loading does not act parallel to a principal fibre direction. Matrix cracking and delaminations are the most common failure modes observed for specimens under low-velocity impact and are intensified by preload.

scholarly journals Residual bending behaviour of sandwich composites after impact

2018 ◽  
Vol 22 (2) ◽  
pp. 402-422 ◽  
Author(s):  
Ismet Baran ◽  
Wouter Weijermars
Keyword(s):  
Polyethylene Terephthalate ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Low Velocity Impact ◽  
Bending Test ◽  
Low Velocity ◽  
Velocity Impact ◽  
Three Point Bending ◽  
Impact Tests ◽  
Styrene Acrylonitrile

This work investigates the residual mechanical behaviour of composite sandwich panels in bending after impact loading conditions. The sandwich panels were made of an epoxy/glass face sheet with three different core materials: styrene acrylonitrile foam, polyethylene terephthalate foam and Balsa wood. A three-point bending test was performed in order to determine the reference stiffness. A low-velocity impact test and thereafter the three-point bending test were performed with the same specimens. The failure modes during bending tests were captured using a high-speed camera. It was found that multiple shear cracks with progressive failure were present in the core of styrene acrylonitrile and polyethylene terephthalate panels in bending after impact tests, whereas single shear crack with sudden failure was the case for Balsa panels. The initial bending stiffness decreased approximately 30.5, 35.2 and 55.6% for Balsa, styrene acrylonitrile and polyethylene terephthalate panels, respectively, in bending after impact tests due to the influence of the pre-damage from the low-velocity impact tests. The reduction in collapse force was also quantified for Balsa, styrene acrylonitrile and polyethylene terephthalate panels as 22.8, 4.9 and 22.1%, respectively.

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