scholarly journals An Optimization Tool for Impact Analysis of Composite Structures

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Impact Loading ◽  
Composite Structures ◽  
Impact Analysis ◽  
Failure Modes ◽  
Drop Test ◽  
Matrix Cracking ◽  
Computational Time ◽  
Failure Behavior ◽  
Test Analysis ◽  
Plane Failure

Composite materials exhibit complex failure behavior under impact loading especially such as that for composite landing gear structure. Possible failure modes in composites may include matrix cracking, fiber breakage, kinking, fiber-matrix debonding or delamination between composite plies. In order to better understand the damage mechanisms and non-linear response of composite structures under impact, complex geometries, materials, ply orientations and stacking sequence need to be considered. However, general drop test analysis for composite structures usually takes a lot of computational efforts, and it may be even more expensive for failure analysis and optimization when various structural geometries and design configurations are taken into account. This paper proposes a new methodology for evaluation and optimization of failure behavior of composite structures subjected to impact loading, whereby drop test analysis of composite structures is modeled by explicitly dynamics analysis of two-dimensional structures and implicit analysis of three-dimensional solid structures to predict delamination or out-of-plane failure. The above-mentioned modeling strategy helps speed up the optimization process and considerably save computational time and efforts. The proposed methodology together with reliable optimization algorithms and failure theory criteria are integrated and coded into a FE optimization tool by Python script. It is shown that the optimization tool effectively helps engineers and researchers perform optimization of general composite structures and fully take into account of various geometries, materials, loading configurations, composite stack-up and sequences and individual ply's orientation.

scholarly journals An effective methodology for drop test analysis and optimization of aerospace composite structures

2019 ◽  
Author(s):  
DC Pham
Keyword(s):  
Composite Structures ◽  
Impact Analysis ◽  
3D Structure ◽  
Structural Response ◽  
Drop Test ◽  
Computationally Efficient ◽  
Test Analysis ◽  
Design And Optimization ◽  
Structural Configurations ◽  
Modeling Strategy

An effective modeling strategy for drop test analysis of composite structures is proposed which allows engineers to generate feasible designs of complex structures undergoing impact. Traditional drop test analysis of 3D structural structures requires careful and detailed modeling and simulation, especially for composite materials where structural response may significantly vary upon changing the composite material properties, layup stacking or ply orientations. To account for various structural configurations, an optimization scheme that is computationally efficient is highly desired for composite design and analysis. This work illustrates a robust modeling strategy for drop test design and optimization of general composite structures by combining an explicit impact analysis of a 2D structural profile and subsequently a quasi-static analysis of the relevant 3D structure. This novel methodology is validated and shows good correlation with experimental results

A Damage Model for Prediction of the Open-Hole Strength of Glare Laminates

2013 ◽  
Vol 325-326 ◽  
pp. 123-127
Author(s):  
Zi Zhen Cao ◽  
Ji Feng Zhang ◽  
Yun Wan ◽  
Yong Gang Xie
Keyword(s):  
Failure Modes ◽  
Damage Model ◽  
Three Dimensional ◽  
Matrix Cracking ◽  
Failure Behavior ◽  
Cohesive Elements ◽  
Fiber Failure ◽  
Solution Approach ◽  
Present Solution ◽  
Open Hole

A three-dimensional progressive damage model is proposed to predict the open-hole tensile strength of Glare laminates. For the glass fiber reinforced epoxy the user subroutine UMAT is employed for description of the failure modes, such as matrix cracking and fiber failure. Behavior of the delamination between plies of the laminate is described using cohesive elements. Laminates with a rhombic hole, a square hole and a circular hole are taken into consideration separately. The results obtained by the present solution approach are validated with those available in the literatures.

A Damage Analysis on the Composite Plate Subjected to Low Velocity Impact

2006 ◽  
Vol 306-308 ◽  
pp. 285-290
Author(s):  
Young Shin Lee ◽  
Hyun Soo Kim ◽  
Young Jin Choi ◽  
Jae Hoon Kim
Keyword(s):  
Composite Structures ◽  
Composite Plate ◽  
Impact Damage ◽  
Laminated Composite ◽  
Matrix Cracking ◽  
Low Velocity Impact ◽  
Failure Behavior ◽  
Low Velocity ◽  
Velocity Impact ◽  
Delamination Failure

The laminated composite structures applied to the wing and the speed brake of an aircraft or the turbine blade of a compressor. These structures may be impacted by birds and hails during operation. They may also be impacted by drop of a tool during manufacture or repair. Unlike high velocity impact damage, which can be easily found by the naked eye, the damage due to low velocity impact may be difficult to detect. Damage which is not detected may cause failure of a structure and result in damage propagation. Growth of damage means reduction of stiffness on the structure. So, exact prediction of damage caused by a low velocity impact is very important in order to guard against sudden failure of the structure. In this study, modified delamination failure criterion has suggested in order to predict the failure behavior of a composite plate subjected to low-velocity impact. The criterion includes the assumption which is matrix cracking mode causes delamination failure. Predicted damage using supposed delamination criterion is similar to experiment results.

Progressive failure analysis for the interaction of interlaminar and intralaminar failure modes in composite structures with an initial delamination

2013 ◽  
Vol 117 (1187) ◽  
pp. 71-85 ◽  
Author(s):  
W. Ji ◽  
A. M. Waas
Keyword(s):  
Failure Analysis ◽  
Composite Laminates ◽  
Composite Structures ◽  
Failure Modes ◽  
Progressive Failure ◽  
Laminated Composite ◽  
Composite Panel ◽  
Analysis Tool ◽  
Plane Failure ◽  
Progressive Failure Analysis

AbstractThis paper is concerned with the development of a failure initiation and progressive failure analysis (PFA) method for advanced composite structures. The present PFA model is capable of predicting interactive out-of-plane and in-plane failure modes observed in fiber reinforced composite laminates including interlaminar behavior and matrix microdamage at the mesoscale. A probability analysis tool is coupled with the PFA to account for uncertainty in modelling parameters caused by material variability and manufacturing inconsistencies. The progressive damage response of a laminated composite panel with an initial delamination is studied and used to demonstrate the PFA modelling framework that is presented here.

scholarly journals Experimental and Numerical Study of Failure Behavior and Energy Mechanics of Rock-Like Materials Containing Multiple Joints

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Ri-hong Cao ◽  
Hang Lin
Keyword(s):  
Strain Energy ◽  
Failure Modes ◽  
Numerical Study ◽  
Boundary Energy ◽  
Jointed Rock ◽  
Failure Behavior ◽  
Dissipation Energy ◽  
Plane Failure ◽  
Energy Mechanism ◽  
Initiation Stress

This paper investigates the influence of joint geometry parameters on the characteristic stress, failure pattern, and energy mechanism of multiple jointed rock-like specimens under uniaxial compression. Both the laboratory and numerical results show that the higher value of UCS occurs when α is around 0° and γ changes from 15° to 30° or when α is around 30° and γ changes from 45° to 75°. However, the lowest value appears when α is around 45° and γ changes from 15° to 30°. The CDiS (critical dilatancy stress) and CIS (crack initiation stress) show a similar tendency to UCS. Moreover, the specimens present different failure modes for various levels of α, γ, and k, and the failure mode can be classified into four categories: stepped path failure; failure through parallel plane; failure through cross plane; material failure. In addition, with higher strength, the input energy and strain energy are higher than those with lower strength. Dissipation energy is affected by the failure modes of the specimens. At the same time, when k changes from 0.2 to 0.6, the boundary energy, strain energy, and dissipation energy show a decreasing trend.

Light emitting composite beams during matrix cracking

2017 ◽  
Vol 51 (30) ◽  
pp. 4251-4260 ◽  
Author(s):  
Kunal Joshi ◽  
Spandan Mishra ◽  
Chris Campbell ◽  
Tarik Dickens ◽  
Arda Vanli
Keyword(s):  
Glass Fiber ◽  
Composite Structures ◽  
Vinyl Ester ◽  
Failure Modes ◽  
Acoustic Emissions ◽  
Matrix Cracking ◽  
Waveform Analysis ◽  
Future Research ◽  
Vinyl Ester Resin ◽  
Flexural Loading

Defects in fiber-reinforced composite structures tend to initiate unpredictably and unalarmed due to local stress concentrations within a composite structure; this has given rise to active monitoring techniques that can quantify the mechanical stress within composites in order to evaluate the structural health. In this paper, triboluminescent mechanisms are used for damage monitoring of composite matrix under flexural loading. Vinyl ester resin is doped with ZnS:Mn phosphors and reinforced with glass fiber whiskers, were subjected to flexural loading while observing both the triboluminescent and acoustic response using a photo multiplier tube (PMT) and micro-mic respectively. Validity of triboluminescent emissions for determining structural integrity of glass fiber / vinyl ester resin composites through individual waveform analysis was examined. Understanding the failure modes through the captured waveform and observed triboluminescent emissions shows that the matrix cracking failure mode tends to lie in the natural frequency range of 2691–2813 Hz. High correlation between the triboluminescent and acoustic signals at matrix cracking at a frequency of 2800 Hz were found. Future research will discuss the triboluminescent and acoustic emissions behavior for delamination and fiber breakage failure modes.

Classification of Delamination and Matrix Cracking in Carbon Fibre Composite Plates Using Acoustic Emission (AE)

2009 ◽  
Author(s):  
Dirk Aljets ◽  
Alex Chong ◽  
Steve Wilcox ◽  
Karen Holford ◽  
Rhys Pullin ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Carbon Fibre ◽  
Composite Structures ◽  
Failure Modes ◽  
Fibre Composite ◽  
Composite Plates ◽  
Matrix Cracking ◽  
Actual Condition ◽  
Carbon Fibre Composite ◽  
Failure Types

Recent publications show that there is an increasing interest in the aircraft industry in monitoring the actual condition of a structure in real time and while the structure is in service. It is hoped that this Structural Health Monitoring (SHM) could make some regular inspections unnecessary and allow maintenance only when required. This is particularly important for CFRP structures for which aircraft manufacturers are increasingly interested. For these new composite structures where the experience of fatigue failure is relatively low, this technique could potentially be economical and improve the safety of the structures. Acoustic Emission is reported to be sensitive to the four failure types in composite materials, namely matrix cracking, delamination, debonding and fibre fracture. These failure modes can have different impacts on structural integrity and it is therefore of interest to identify these failure types before further maintenance steps are conducted. This report discusses different features in AE signals which can be used to identify the actual flaw type. These features were then applied to AE data collected from two different experiments on carbon fibre composite plates. These experiments were designed to induce the two different failure modes of matrix cracking and delamination. The data collected was used to train a neural network to recognise the two failure modes.

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 Analytical and Experimental Simulation of Fan Blade Behaviour and Damage Under Bird Impact

1990 ◽  
Author(s):  
H. C. Teichman ◽  
R. N. Tadros
Keyword(s):  
Impact Analysis ◽  
Failure Modes ◽  
Structural Response ◽  
Analytical Models ◽  
Experimental Simulation ◽  
Experimental Program ◽  
Test Analysis ◽  
Contact Algorithm ◽  
Bird Impact ◽  
Fan Blade

An extensive analytical and experimental program has been undertaken to investigate the Foreign Object Damage resistance capabilities of external components for small gas turbofan engines. A transient nonlinear impact analysis has been used to predict the structural response of fan blades under bird ingestion conditions. This analysis is based on finite elements, a 3-D bird load model and an interactive structure-to-bird contact algorithm. Experiments were designed and carried out to record large blade deformations during bird impact, and were used to validate and calibrate the analytical models. The analytical models and testing program are described, and dominant fan blade response and failure modes are presented. Predicted results demonstrate good correlation with test. Analysis application to fan blade design and other engine components is recommended.

scholarly journals Investigation of Ib-Values for Determining Fracture Modes in Fiber-Reinforced Composite Materials by Acoustic Emission

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3641
Author(s):  
Doyun Jung ◽  
Woong-Ryeol Yu ◽  
Wonjin Na
Keyword(s):  
Acoustic Emission ◽  
Failure Modes ◽  
Peak Frequency ◽  
Matrix Cracking ◽  
Failure Behavior ◽  
B Values ◽  
Fracture Modes ◽  
Reinforced Composite ◽  
Carbon Fiber Epoxy ◽  
Ae Signals

This study analyzed failure behavior using Ib-values obtained from acoustic emission (AE) signals. Carbon fiber/epoxy specimens were fabricated and tested under tensile loads, during which AE signals were collected. The dominant peak frequency exhibited a specific range according to fracture mode, depending on the fiber structures. Cross-ply specimens, with all fracture modes, were used and analyzed using b- and Ib-values. The b-values decreased over the specimens’ entire lifetime. In contrast, the Ib-values decreased to 60% of the lifetime, and then increased because of the different fracture behaviors of matrix cracking and fiber fracture, demonstrating the usefulness of Ib-values over b-values. Finally, it was confirmed that abnormal conditions could be analyzed more quickly using failure modes classified by Ib-values, rather than using full AE data.

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