scholarly journals Evaluation of test methods and face-sheet thickness effects in damage tolerance assessment of composite sandwich plates

2021 ◽  
pp. 109963622110369
Author(s):  
Moeen S Rajput ◽  
Magnus Burman ◽  
Stefan Hallström
Keyword(s):  
Impact Strength ◽  
Impact Assessment ◽  
Impact Damage ◽  
Test Methods ◽  
Test Method ◽  
Face Sheet ◽  
Composite Sandwich ◽  
Compression After Impact ◽  
Post Impact ◽  
Impact Damages

Composite sandwich materials provide high bending performance-to-weight ratios. However, these materials are vulnerable to impact damages which can drastically reduce their load-bearing capability. Presently there is a lack of standardised test methods for impact assessment. This study compares three different test methods for impact assessment; single skin compression after impact (CAI-SS), sandwich compression after impact (CAI-SW) and four-point bending-after-impact (BAI). The CAI-SS test method shows high compressive strength and strain at failure and the tesr is relatively easy to evaluate. For finite size plates with significant impact damage, the CAI-SS test method is recommended for post impact strength assessment. For large sandwich panels with relatively small impact damages the CAI-SW test method could be more relevant since it includes effects of panel asymmetry generated from the impact damage. The BAI test method may be recommended as an alternative to CAI but quite long specimens are required in order to assure compressive failure in the tested face-sheet, making the test both demanding and expensive. On the other hand, lower load levels are required to break the specimens and there is less need for precise machining during specimen manufacturing. A finite element model including progressive damage evolution was used to estimate the post impact strength. The simulations showed generally good agreement with the experiments.

Comparison of the impact damage resistance of non-hybrid and intra-ply hybrid carbon/E-glass/polypropylene non-crimp thermoplastic composites

2018 ◽  
Vol 38 (1) ◽  
pp. 31-45 ◽  
Author(s):  
Gaye Kaya
Keyword(s):  
Damage Tolerance ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Thermoplastic Composites ◽  
Low Velocity ◽  
Impact Properties ◽  
Compression After Impact ◽  
Post Impact ◽  
The Impact ◽  
Hybrid Carbon

This study aims to compare the low-velocity impact and post-impact properties of intra-ply hybrid carbon/E-glass/polypropylene non-crimp thermoplastic composites with non-hybrid carbon/PP and E-glass/PP non-crimp thermoplastic composites. Impact test was performed at four energy levels as 15 J, 30 J, 45 J and 60 J. Post-impact properties of hybrid thermoplastic composites were tested by compression after impact method for each energy level to understand the impact damage tolerance of intra-ply hybrid carbon/E-glass/PP non-crimp thermoplastic composites. The effect of hybridization on energy absorption of composites was not significant, while C-scan results showed that the intra-ply hybrid non-crimp thermoplastic composites had smaller impact damage areas in comparison to the non-hybrid samples. Compression and compression after impact tests results confirmed that the intra-ply hybridization increased the toughness of the composite laminates. Also, the residual compression strength/modulus increased with hybridization which indicated to damage tolerance.

Foreign Object Damage in an Oxide/Oxide Composite at Ambient Temperature

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Sung R. Choi ◽  
Donald J. Alexander ◽  
Robert W. Kowalik
Keyword(s):  
Impact Strength ◽  
Ambient Temperature ◽  
Impact Damage ◽  
Ceramic Matrix Composite ◽  
High Energy ◽  
Strength Degradation ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Oxide Composite ◽  
Post Impact

Foreign object damage behavior of an oxide/oxide (N720/AS) ceramic matrix composite was determined at ambient temperature using impact velocities ranging from 100 m/s to 400 m/s by 1.59 mm diameter steel-ball projectiles. Two different support configurations of target specimens were used: fully supported and partially supported. The degree of post-impact strength degradation increased with increasing impact velocity and was greater in a partially supported configuration than in a fully supported one. For the fully supported configuration, frontal contact stress played a major role in generating composite damage, while for the partially supported case, both frontal contact and backside flexure stresses were the combined sources of damage generation. The oxide/oxide composite was able to survive high energy (∼1.3 J) impacts without complete structural failure. The degree of relative post-impact strength degradation of the oxide/oxide composite was similar to that of an advanced SiC/SiC composite observed from a previous study, regardless of the type of specimen support. Like the SiC/SiC composite, impact-damage tolerance was greater in the oxide/oxide than in monolithic silicon nitride ceramics for impact velocities >300 m/s.

scholarly journals On Simulation of Impact Damage in Composite Laminate

1995 ◽  
Vol 4 (1) ◽  
pp. 096369359500400
Author(s):  
Y. Xiong
Keyword(s):  
Impact Strength ◽  
Prediction Model ◽  
Stress Analysis ◽  
Variational Approach ◽  
Composite Laminate ◽  
Impact Damage ◽  
Finite Width ◽  
Compression After Impact ◽  
Soft Inclusion ◽  
The Impact

A complex variational approach is proposed for the stress analysis of a finite composite laminate containing soft inclusion of elliptical shape which simulates the impact damage. The finite width correction is avoided by using this approach in the prediction model for the compression-after-impact strength of laminates. Comparisons with the FEM and test date are made and presented to verify the accuracy of the approach proposed.

Experimental, analytical and numerical study of mechanical properties and fracture energy for composite sandwich beams

2017 ◽  
Vol 21 (3) ◽  
pp. 1167-1189 ◽  
Author(s):  
M Evren Toygar ◽  
Kong Fah Tee ◽  
Farshid Khosravi Maleki ◽  
A Cagla Balaban
Keyword(s):  
Fracture Energy ◽  
Failure Modes ◽  
Flexural Rigidity ◽  
Numerical Study ◽  
Sheet Material ◽  
Strain Energy Release ◽  
Test Method ◽  
Face Sheet ◽  
Shear Stresses ◽  
Composite Sandwich

In this study, the mechanical and fracture behaviour of marine sandwich-structured composite that is manufactured by vacuum-assisted resin infusion process with a PVC foam-web core, and different thicknesses of upper and lower glass fibre-reinforced polymer face sheets used as outer and inner side of the hull have been examined. The properties of PVC core, face sheet material, and composite sandwich structures are presented. Failure modes include sandwich flatwise tension, core flatwise compression, sandwich edgewise compression, and face sheet bending of manufactured composites have been investigated experimentally for marine application. The analytical solution is derived to calculate the flexural rigidity, shear stresses and maximum tensile, compression stresses in three-point bending specimens for marine sandwich composites. 3 End Notched Flexure test method has been applied to calculate the strain energy release rate. Moreover, the finite element study is carried out by using a 2D model to calculate the fracture energy (J) value numerically and virtual crack closure technique. Reasonably good results are obtained between analytical and numerical methods.

The Influence of GI and GII on the compression after impact strength of carbon fiber/epoxy laminates

2017 ◽  
Vol 52 (8) ◽  
pp. 991-1003 ◽  
Author(s):  
Alan Tate Nettles ◽  
Luke Scharber
Keyword(s):  
Carbon Fiber ◽  
Impact Strength ◽  
Compression Strength ◽  
Epoxy Resins ◽  
Impact Damage ◽  
Compression After Impact ◽  
The Difference ◽  
Type Of Failure ◽  
Carbon Fiber Epoxy ◽  
Residual Compression

This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245–665 J/m2 and approximate GII values of 840–2275 J/m2. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for the loss of compression strength.

scholarly journals Impact Performance and Bending Behavior of Carbon-Fiber Foam-Core Sandwich Composite Structures in Cold Arctic Temperature

2020 ◽  
Vol 4 (3) ◽  
pp. 133
Author(s):  
M.H. Khan ◽  
Bing Li ◽  
K.T. Tan
Keyword(s):  
Carbon Fiber ◽  
Impact Damage ◽  
Matrix Cracking ◽  
Face Sheet ◽  
Foam Core ◽  
Impact Performance ◽  
Post Impact ◽  
Bending Behavior ◽  
Impact Bending ◽  
The Impact

This study investigates the impact performance, post-impact bending behavior and damage mechanisms of Divinycell H-100 foam core with woven carbon fiber reinforced polymer (CFRP) face sheets sandwich panel in cold temperature Arctic conditions. Low-velocity impact tests were performed at 23, −30 and −70 °C. Results indicate that exposure to low temperature reduces impact damage tolerance significantly. X-ray microcomputed tomography is utilized to reveal damage modes such as matrix cracking, delamination and fiber breakage on the CFRP face sheet, as well as core crushing, core shearing and debonding in the Polyvinyl Chloride (PVC) foam core. Post-impact bending tests reveal that residual flexural properties are more sensitive to the in-plane compressive property of the CFRP face sheet than the tensile property. Specifically, the degradation of flexural strength strongly depends on pre-existing impact damage and temperature conditions. Statistical analyses based on this study are employed to show that flexural performance is dominantly governed by face sheet thickness and pre-bending impact energy.

Foreign Object Damage in an Oxide/Oxide Composite at Ambient Temperature

2008 ◽  
Author(s):  
Sung R. Choi ◽  
Donald J. Alexander ◽  
Robert W. Kowalik
Keyword(s):  
Impact Strength ◽  
Ambient Temperature ◽  
Impact Damage ◽  
Ceramic Matrix Composite ◽  
High Energy ◽  
Strength Degradation ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Oxide Composite ◽  
Post Impact

Foreign object damage (FOD) behavior of an oxide/oxide (N720/AS) ceramic matrix composite (CMC) was determined at ambient temperature using impact velocities ranging from 100 to 400 m/s by 1.59-mm diameter steel-ball projectiles. Two different support configurations of target specimens were used: fully supported and partially supported. The degree of post-impact strength degradation increased with increasing impact velocity, and was greater in a partially supported configuration than in a fully supported one. For the fully supported configuration, frontal contact stress played a major role in generating composite damage, while for the partially supported case both frontal contact and backside flexure stresses were the combined sources of damage generation. The oxide/oxide composite was able to survive high energy (∼1.3 J) impacts without complete structural failure. The degree of relative post-impact strength degradation of the oxide/oxide composite was similar to that of an advanced SiC/SiC composite observed from a previous study, regardless of the type of specimen support. Like the SiC/SiC composite, impact-damage tolerance was greater in the oxide/oxide than in monolithic silicon nitride ceramics for impact velocities >300 m/s.

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