Behavior of Thin, Moderately Thick and Thick Woven Composites Subjected to Low Velocity Impact Loads

2002 ◽  
Author(s):  
Ajit D. Kelkar
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Experimental Program ◽  
Weight System ◽  
Impact Loads ◽  
Composite Panels ◽  
Woven Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact

The effects of low velocity impact on woven composite panels are presented in this study. In the experimental program, 8 ply, 16 ply and 24 ply VARTM manufactured woven composite panels were subjected to low velocity impact loads. The laminates were held in a special fixture, which was designed to simulate simply supported boundaries. Impact experiments were conducted using a Dynatup low velocity impact testing machine where a drop-weight system was used to strike each panel at 90° incidence under controlled conditions of impact velocity. The impactor used was of a constant weight and tip diameter. The impact height and hence the velocity and energy were used as variables in the study. Preliminary impact tests were performed to establish the incipient damage (lower bound) and visible back face damage and spalling (upper bound) energy for each of the 8 ply (thin), 16 ply (moderately thick) and 24 ply (thick) woven graphite/epoxy laminates. Seven energy levels were selected to study the progressive deformation and damage mechanics. It is shown that threshold damage criteria can be established by using a simple FFT smoothening of impact load-time history data.

Low Velocity and Compression-After-Impact Response of Pin-Reinforced Sandwich Composites

1999 ◽  
Author(s):  
Uday K. Vaidya ◽  
Mohan V. Kamath ◽  
Mahesh V. Hosur ◽  
Anwarul Haque ◽  
Shaik Jeelani
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Static Compression ◽  
Velocity Impact ◽  
Transverse Stiffness ◽  
Impact Studies ◽  
Compression After Impact ◽  
The Impact

Abstract In the current work, sandwich composite structures with innovative constructions referred to as Z-pins, or truss core pins are investigated, in conjunction with traditional honeycomb and foam core sandwich constructions, such that they exhibit enhanced transverse stiffness, high damage resistance and furthermore, damage tolerance to impact. While the investigations pertaining to low velocity impact have appeared recently in Vaidya et al. 1999, the current paper deals with compression-after-impact studies conducted to evaluate the residual properties of sandwich composites “with” and “without” reinforced foam cores. The resulting sandwich composites have been investigated for their low velocity (< 5 m/sec) impact loading response using instrumented impact testing at energy levels ranging from 5 J to 50 J impact energy. The transverse stiffness of the cores and their composites has also been evaluated through static compression studies. Compression-after-impact studies were then performed on the sandwich composites with traditional and pin-reinforcement cores. Supporting vibration studies have been conducted to assess the changes in stiffness of the samples as a result of the impact damage. The focus of this paper is on the compression-after-impact (CAI) response and vibration studies with accompanying discussion pertaining to the low velocity impact.

scholarly journals Ultrasonic Analysis of Damage in CFRP Resulting from Static Indentation and Low Velocity Impact

1993 ◽  
Vol 2 (3) ◽  
pp. 096369359300200
Author(s):  
H. Kaczmarek
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Ultrasonic Tomography ◽  
Transverse Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Testing Procedures ◽  
Damage Initiation ◽  
Static Indentation ◽  
The Impact

In order to reduce hidden damage caused in CFRP by low velocity transverse impact, testing procedures must be established by understanding the impact phenomena and the roles of various parameters on damage initiation and growth. Hence, composite plates were stressed and an original method, “ultrasonic tomography,” was applied to detect delaminations on the interfaces. The results show the similarity of the damage growth resulting from static indentation and low velocity impact.

Impact Damage and Strength Reduction Behavior of Honeycomb Sandwich Structure Subjected to Low Velocity Impact

2006 ◽  
Vol 306-308 ◽  
pp. 279-284
Author(s):  
Ki Weon Kang ◽  
Jung Kyu Kim ◽  
Heung Seob Kim
Keyword(s):  
Sandwich Structure ◽  
Impact Damage ◽  
Testing Machine ◽  
Strength Reduction ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Reduction Behavior ◽  
Velocity Impact ◽  
The Impact

The goals of the paper are to identify the impact damage and strength reduction behavior of sandwich structure, composed of carbon/epoxy laminates skin and Nomex core with two kinds of thickness (10 and 20mm). For these, low velocity impact tests were conducted using the instrumented impact-testing machine and damages are inspected by SAM. And then, subsequent static tests are conducted under flexural loading to identify the strength reduction behavior of the impacted sandwich structures. The impact damages are mainly delamination in carbon/epoxy skin and their behavior is mostly independent of core thickness. Also, their energy absorbing behavior is identified through calculating the energy absorbed by impact damage. Finally, the strength reduction behavior is evaluated through Caprino’s model, which was proposed on the unidirectional laminates.

Investigation of the Effects of Core Thickness on Low Velocity Impact Behaviors of Aluminum Honeycomb Composites

2021 ◽  
Author(s):  
Kasım Karataş ◽  
Okan Özdemir
Keyword(s):  
Sheet Material ◽  
Energy Levels ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Core Material ◽  
Low Velocity ◽  
Velocity Impact ◽  
Impact Tests ◽  
Aluminum Honeycomb ◽  
The Impact

Honeycomb structures are used where the weight to strength ratio is important. They are also preferred to absorb the energy from the blows received. In this study, low velocity impact behavior of aluminum honeycomb composites with different core thicknesses were investigated. Aluminum honeycombs used in this study are AL3003 honeycombs of 10 mm and 15 mm thicknesses. Glass fiber reinforced epoxy sheets with a thickness of 2 mm were used as the surface sheet material. Composite plates were produced by vacuum infusion method. The upper and lower face plates were cut in dimensions of 100x100 mm. The cut plates were attached to the core material with adhesive and a sandwich structure was formed. After bonding, low velocity impact tests were performed on these test samples at 40J, 100J and 160J energy levels using the composite CEAST Fractovis Plus impact testing machine. According to the results obtained from the impact tests, at higher energy levels, 15 mm thick composites have 10-15% higher energy absorption capacity than 10 mm.

Experimental and numerical behaviors of GFRP laminates under low velocity impact

2020 ◽  
Vol 54 (21) ◽  
pp. 2999-3007
Author(s):  
Hüseyin E Yalkın ◽  
Ramazan Karakuzu ◽  
Tuba Alpyıldız
Keyword(s):  
Contact Force ◽  
Impact Energy ◽  
Damage Mechanics ◽  
Matrix Material ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Wide Range ◽  
The Impact

The aim of the study is to investigate the behavior of laminated composites under low velocity impact both experimentally and numerically. With this aim, the effects of wide range impact energy values between 10 J and 60 J were evaluated experimentally and numerically for the laminate of [±45/(0/90)2]S oriented unidirectional E-glass as reinforcing material and epoxy resin for matrix material. Different impactor velocities were used to maintain the impact energy values and experimental impact tests were generated with drop weight impact testing machine at room temperature. Numerical simulations were performed using LS-DYNA finite element analysis software with a continuum damage mechanics-based material model MAT058. Contact force between impactor and laminate, and transverse deflection at the center of laminate results were obtained as a function of time and used to plot contact force–time curves, contact force–deflection curves and absorbed energy-impact energy curves. Also, delamination area was examined. Finally, numerical results were compared with experimental results and a good correlation between them was observed.

scholarly journals Impact and Post Impact Behavior of Hybrid Composites

2018 ◽  
Vol 11 (4) ◽  
pp. 46-52
Author(s):  
Aidel Kadum Jassim Al-shamary
Keyword(s):  
Impact Energy ◽  
Hybrid Composites ◽  
Energy Levels ◽  
Testing Machine ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact

In this study, the effect of low velocity impact  response of Kevlar/carbon hybrid composite has been investigated. Then the impacted specimens were subjected to compression and buckling tests at room temperature experimentally. The height, width and thickness of the specimens are 150, 100 and 2.1 mm, respectively. Impact tests have been performed under different impact energy levels by using low velocity impact testing machine. Compression and buckling tests were conducted by Shimadzu testing machine. According to obtained results, the damage increases by increasing the impact energy level in the subjected specimens to impact test.  Compression strength value is higher about 3  times than buckling strength value.

scholarly journals Structural Damage Characteristics of a Layer-to-Layer 3-D Angle-Interlock Woven Composite Subjected to Drop-Weight Impact

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Qian Ma ◽  
Ke Wang ◽  
Shudong Wang ◽  
Yiwei Ouyang ◽  
Zhiqiang Lin ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Structural Damage ◽  
Low Velocity Impact ◽  
Woven Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Characteristics ◽  
Drop Weight ◽  
The Impact

AbstractThe most attractive structural feature of the three-dimensional (3D) angle-interlock woven structure is that the straight weft yarns are bundled by the undulated warp yarns, which induces the overall good structural stability and a stable fabric structure. Thus the 3-D angle-interlock woven composite (3DAWC) prepared by the vacuum-assisted resin transfer molding (VARTM) curing process has excellent mechanical properties by using the fabric and epoxy resin as the reinforcement and matrix, respectively. The low-velocity impact damage properties of the composites under different drop-weight energies (70, 80, and 100 J) were tested experimentally. The load–displacement curves, energy–time curves, and the ultimate failure modes were obtained to analyze the performance of resistance to low-velocity impact, as well as the impact energy absorption effect and failure mechanism, especially the structural damage characteristics of the 3DAWC subjected to the low-velocity impact of drop weight. By analyzing the obtained experimental results, it is found that the fabric reinforcement is the primary energy absorption component and the impact energy mainly propagates along the longitudinal direction of the yarns, especially the weft yarn system, which is arranged in a straight way. In addition, as the impact energy increases, the energy absorbed and dissipated by the composite increases simultaneously. This phenomenon is manifested in the severity of deformation and damage of the material, i.e., the amount of deformation and size of the damaged area.

scholarly journals Low Velocity Impact and Creep-Strain Behaviour of Vinyl Ester Matrix Nanocomposites Based on Layered Silicate

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
A. I. Alateyah ◽  
H. N. Dhakal ◽  
Z. Y. Zhang ◽  
B. Aldousiri
Keyword(s):  
Electron Microscopy ◽  
Vinyl Ester ◽  
Creep Behaviour ◽  
Layered Silicate ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Neat Polymer ◽  
Velocity Impact ◽  
The Impact

The impact properties of neat vinyl ester and the nanocomposites were performed using a low velocity impact testing. The addition of layered silicate into the polymer matrix shows that an optimum range of nanoclay reinforcement in the vinyl ester matrix can produce enhanced load bearing and energy absorption capability compared to the neat matrix. In addition, the amount of microvoids in the nanocomposites structure influences the overall properties. Likewise, the influence of the clay addition into the neat polymer on the creep relaxation behaviour at 25°C and 60°C was studied. In both cases, the presence of the layered silicate remarkably improved the creep behaviour. The improvement of these properties can be assigned to the stiff fillers and the configurational linkage between the polymer and the layered silicate which are supported by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterisations by showing a distinct change in surface morphology associated with improved impact toughness and creep response.

Peridynamic modeling of low-velocity impact damage in laminated composites reinforced with z-pins

2018 ◽  
Vol 52 (25) ◽  
pp. 3491-3508 ◽  
Author(s):  
Forrest Baber ◽  
Vipul Ranatunga ◽  
Ibrahim Guven
Keyword(s):  
Failure Modes ◽  
Impact Damage ◽  
Impact Testing ◽  
Matrix Cracking ◽  
Low Velocity Impact ◽  
Identification Algorithm ◽  
Low Velocity ◽  
New Approach ◽  
Velocity Impact ◽  
The Impact

In this study, a new approach for predicting damage and specific failure modes in laminated fiber reinforced composites is presented. The new method is based on the peridynamic theory and models individual plies, and represents fiber and matrix materials in each ply explicitly. These features enable analysis of laminates with arbitrary fiber orientation in a convenient manner. Additionally, a new failure mode identification algorithm has been developed and implemented. Instead of the conventional peridynamic damage parameter, the new algorithm works with individual broken bonds, which makes identification of different failure modes including matrix cracking, fiber breakage, and delamination straight-forward and unambiguous. The new peridynamic approach is demonstrated by considering the low-velocity impact damage on composite laminates with and without translaminar reinforcements. The translaminar reinforcement technique considered in this study is z-pinning; two different geometric configurations of z-pins are explored. The impact testing and the post-impact nondestructive evaluations with ultrasonic c-scans are performed at the Air Force Research Laboratory to characterize the delaminations. The impact tests on different samples are simulated using the current peridynamic approach. The predicted impact damage failure modes are compared against the experimental measurements. The new approach is shown to capture low-velocity impact damage both quantitatively and qualitatively.

Low Velocity Impact Behavior of SiC/PU/GFRP Laminates

2016 ◽  
Vol 725 ◽  
pp. 122-126 ◽  
Author(s):  
Kumar V. Akshaj ◽  
Chandra Khan Vishwas ◽  
G. Balaganesan ◽  
M.S. Sivakumar
Keyword(s):  
Energy Absorption ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Fiber Failure ◽  
Velocity Impact ◽  
Drop Mass ◽  
Set Up ◽  
The Impact

This paper discusses the energy absorption during low velocity impact on target with combinations of PU foam, SiC inserts/plate bonded to GFRP composite backing. SiC inserts and SiC plates are bonded as front layer to enhance energy absorption. Low velocity impact is conducted by using drop mass set-up and mild steel spherical nosed impactor is used for impact testing of target in fixed boundary conditions. Failure in the case of SiC inserts is local as only the insert under the impact is damaged and nearby areas are intact. However, in the other cases, the SiC plate is damaged along with fiber failure and delamination on the composite backing layer. It is observed that the energy absorbed by SiC plate is higher than that absorbed by SiC inserts layered target.

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