RESIDUAL STRENGTH OF SANDWICH STRUCTURE SUBJECTED TO LOW VELOCITY IMPACT

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4384-4389 ◽  
Author(s):  
KI-WEON KANG ◽  
JUNG-KYU KIM ◽  
SEONG-KYUN CHEONG ◽  
HEUNG-SEOB KIM
Keyword(s):  
Residual Strength ◽  
Sandwich Structure ◽  
Strength Reduction ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Reduction Behavior ◽  
Static Tests ◽  
Velocity Impact ◽  
Impact Tester ◽  
The Impact

The goals are to identify the strength reduction behavior and its statistical properties of sandwich structure subjected to low velocity impact. For these, the impact tests were performed using the impact tester and the damages are inspected by SAM. And then, subsequent static tests are conducted under flexural loading for the impacted structures. The strength reduction behavior is evaluated via the residual strength prediction model. Also, a statistical model is developed to identify the fluctuation of residual strength. The model well describes the distribution of residual strength.

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.

Analysis on Low Velocity Impact Damage and Compressive Residual Strength of Composite Laminates

2014 ◽  
Vol 566 ◽  
pp. 463-467
Author(s):  
Pu Xue ◽  
H.H. Chen ◽  
W. Guo
Keyword(s):  
Experimental Data ◽  
Residual Strength ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Impact Damage ◽  
Numerical Results ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact

This paper studies the impact damage under low velocity impact for composite laminates based on a nonlinear progressive damage model. Damage evolution is described by the framework of the continuum damage mechanics. The real impact damage status of composite laminates has been used to analyze the residual compressive strength instead of assumptions on damage area after impact. The validity of the methodologies has been demonstrated by comparing the numerical results with the experimental data available in literature. The delamination area has an error of 11.3%. The errors of residual strength and compressive displacement are 8.9% and 15%, which indicate that the numerical results matched well with the experimental data.

The Use of Quasi-Static Indentation Testing to Evaluate Low-Velocity Impact Resistance of Ex Situ Toughened Composite

2014 ◽  
Vol 697 ◽  
pp. 35-40
Author(s):  
Hui Min Dong ◽  
Xue Feng An ◽  
Xiao Su Yi ◽  
Zheng Tao Su
Keyword(s):  
Impact Damage ◽  
Low Velocity Impact ◽  
Ex Situ ◽  
Indentation Testing ◽  
Low Velocity ◽  
Static Tests ◽  
Velocity Impact ◽  
Fibre Failure ◽  
Static Indentation ◽  
The Impact

The aim of this study was to investigate the valuable impact damage parameters from quasi-static indentation testing to access the low-velocity impact behaviour of ex-situ toughened composites by comparing low-velocity impact and quasi-static test results (the same boundary conditions). In terms of the delamination damage threshold load and indentation depth, quasi-static tests predicted the impact damage resistance well. However, only very conservative estimates of maximum load due to the final fibre failure under higher energy level were achieved. This phenomenon is attributed to two factors. First, energy during quasi-static indentation event is completely transformed or absorbed by the laminate, where it is stored elastically in panel bending or absorbed by the creation of damage, without the energy in the form of vibration, heat, inelastic behaviour of the impactor or the supports. Second, strain rate effect may have a remarkable influence on the fibre failure but on undamaged and delaminated damage.

Development of a mathematical model to analyze residual strength of composites after low-velocity impact

2018 ◽  
Vol 53 (8) ◽  
pp. 738-745 ◽  
Author(s):  
Camila Medeiros Dantas de Azevedo ◽  
Rayane Dantas da Cunha ◽  
Raimundo Carlos Silverio Freire Junior ◽  
Wanderley Ferreira de Amorim Junior
Keyword(s):  
Residual Strength ◽  
Composite Laminates ◽  
Repair Process ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Three Point Bending ◽  
Compression After Impact ◽  
Strength And Stiffness ◽  
The Impact

This study aimed to develop a model to analyze the residual strength of composites after low-velocity impact, using three-point bending and compression after impact tests. Two types of composite laminates with an orthophthalic polymer matrix were used: one reinforced with bidirectional E-glass fabric and the other reinforced with bidirectional Kevlar-49 fabric. To that end, an equation was developed to assess loss of strength and stiffness after impact at different distances from the impact point, and this equation was not found in any previously searched article. The results demonstrate that the laminate based in glass fiber is more appropriate for the repair process.

Residual Strength after Low Velocity Impact in Carbon-Epoxy Laminates

2006 ◽  
Vol 514-516 ◽  
pp. 624-628 ◽  
Author(s):  
Ana M. Amaro ◽  
Paulo N.B. Reis ◽  
Marcelo F.S.F. de Moura
Keyword(s):  
Residual Strength ◽  
Testing Machine ◽  
Experimental Tests ◽  
Low Energy ◽  
Low Velocity Impact ◽  
Stacking Sequence ◽  
Low Velocity ◽  
Velocity Impact ◽  
Impact Energies ◽  
The Impact

The aim of present work is to study the influence of low energy impacts on residual strength of carbon-epoxy laminates. Experimental tests were performed on [0,90,0,90]2s and [0,90]8 laminates using a drop weight-testing machine. The influence of the laminate stacking sequence is analysed under 1.5 J, 2 J, 2.5 J and 3 J impact energies, corresponding to a 0.91 ms-1, 1.05 ms-1, 1.18 ms-1 and 1.29 ms-1 of impact velocity, respectively. The impacted plates were inspected by CScan to evaluate the size, shape and position of the delaminations through the thickness of the plate. The same plates were inspected by C-Scan before the impact, to evaluate the eventual presence of defects produced during the manufacturing process. The residual flexural strength showed that the [0,90,0,90]2s laminates have better performance than the [0,90]8 ones. The explanation is related with the lower flexural stiffness of the antisymmetric lay-up relatively to the symmetric one.

Dynamic Response of Two-Core Sandwich Composite Structures under Impact

2008 ◽  
Vol 136 ◽  
pp. 115-124
Author(s):  
Da Zhi Jiang ◽  
Fu Biao Yang ◽  
Su Li Xing ◽  
Jia Yu Xiao
Keyword(s):  
Composite Structures ◽  
Sandwich Structure ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
Local Displacement ◽  
The Core ◽  
Shear Strains ◽  
The Impact

Traditional sandwich structure consists of two face sheets and a core. With an internal sheet inserted into the core, a two-core sandwich structure is then formed. Two-core sandwich structures with composite laminated face sheets and a thin internal sheet subjected to low velocity impact are studied in this paper. Local displacement of the core under the point of impact is investigated. Simulated results show that the local displacement of the core along the direction of the impact has been decreased significantly by introducing the internal sheet into a traditional single sandwich structure and by reducing the space between the internal sheet and the impacted face sheet. Shear deformation in the cores of a two-core sandwich structure is also investigated and attention is focused on shear strains on interfaces between face/internal sheets and the cores. Results further show that strain levels in selected elements at the interested interfaces depend upon locations of the selected elements and arrangements of the internal sheet.

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