Damage characteristics of open-hole laminated composites subjected to longitudinal loads

2019 ◽  
Vol 230 ◽  
pp. 111474 ◽  
Author(s):  
Di Zhang ◽  
Xitao Zheng ◽  
Tianchi Wu
Keyword(s):  
Laminated Composites ◽  
Damage Characteristics ◽  
Open Hole

Progressive Fatigue Damage Simulation in Laminated Composites Based on Explicit Finite Element Formulation

2019 ◽  
Vol 64 (2) ◽  
pp. 1-12
Author(s):  
Yuri Nikishkov ◽  
Guillaume Seon ◽  
Andrew Makeev
Keyword(s):  
Finite Element ◽  
Laminated Composites ◽  
Test Methods ◽  
Remaining Useful Life ◽  
Image Correlation ◽  
Progressive Damage ◽  
Damage Analysis ◽  
Explicit Finite Element ◽  
Analysis Methods ◽  
Open Hole

Advanced polymeric composites are playing a major role in designing high-performance and lightweight vertical lift structures. However, uncertain residual strength and remaining useful life of the composite rotor and airframe structures due to complexity of failure mechanisms and susceptibility to manufacturing irregularities, which may be precursors to structural damage, impose risks that cannot be mitigated exclusively by time-consuming and costly experimental iterations. Validated analysis techniques accelerating design, certification, and qualification of composite structures are needed. Our team has been taking essential steps toward improving confidence in material qualification for laminated composites. The first step started with our reduced lamina test methods, short-beam shear, and small-plate twist based on digital image correlation measuring as a subset the standard material properties and, in addition, key properties that cannot be currently measured using any standard test methods. The lamina properties provide essential material input data for laminate analysis. The laminate analysis was the second step increasing confidence in material qualification. A known weakness of the existing progressive damage analysis methods is the lack of effective techniques to predict ultimate failure. The newly developed methodology relies on explicit finite element modeling and eliminates convergence issues in the ply-level progressive damage analysis methods due to severe nonlinear discontinuities after propagation of damage beyond detectable size. This work shows results of applying this methodology to nanosilica-toughened IM7/PMT-F3GHT open-hole tension strength/fatigue, open-hole compression strength/fatigue, and bearing strength multidirectional laminate configurations. The ability to predict progression of damage from initiation to ultimate strength and fatigue for advanced material systems including IM7/PMT-F3GHT carbon/epoxy reinforced by nanosilica has been demonstrated for the first time.

Damage characteristics in laminated composite structures subjected to low-velocity impact

2019 ◽  
Vol 11 (5) ◽  
pp. 670-685 ◽  
Author(s):  
Konstantinos Stamoulis ◽  
Stelios K. Georgantzinos ◽  
G.I. Giannopoulos
Keyword(s):  
Numerical Modeling ◽  
Impact Damage ◽  
Laminated Composites ◽  
Time Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Content Type ◽  
Velocity Impact ◽  
Damage Characteristics ◽  
Force Time

Purpose The present study deals with the numerical modeling of the low-velocity impact damage of laminated composites which have increasingly important applications in aerospace primary structures. Such damage, generated by various sources during ground handling, substantially reduces the mechanical residual performance and the safe-service life. The purpose of this paper is to present and validate a computationally efficient approach in order to explore the effect of critical parameters on the impact damage characteristics. Design/methodology/approach Numerical modeling is considered as one of the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intralaminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS® programme. Findings The employed modeling approach is validated using corresponding numerical data found in the literature and the presented results show a reasonable correlation to the available literature data. It is demonstrated that the current model can be used to capture the force-time response as well as damage parameter maps showing the intralaminar damage evolution for different impact cases with respect to the physical boundary conditions and a range of impact energies. Originality/value Low-velocity impact damage of laminated composites is still not well understood due to the complexity and non-linearity of the damage zone. The presented model is used to predict the force-time response which is considered as one of the most important parameters influencing the structural integrity. Furthermore, it is used for capturing the damage shape evolution, exhibiting a high degree of capability as a damage assessment computational tool.

Static strength prediction in laminated composites by using discrete damage modeling

2016 ◽  
Vol 51 (10) ◽  
pp. 1473-1492 ◽  
Author(s):  
Kevin Hoos ◽  
Endel V Iarve ◽  
Michael Braginsky ◽  
Eric Zhou ◽  
David H Mollenhauer
Keyword(s):  
Compressive Strength ◽  
Input Data ◽  
Damage Mechanics ◽  
Laminated Composites ◽  
Matrix Cracking ◽  
Damage Modeling ◽  
Fiber Failure ◽  
Failure Patterns ◽  
Open Hole ◽  
Discrete Damage Modeling

Discrete Damage Modeling of complex local failure patterns in laminated composites including matrix cracking, delamination, and fiber failure was performed. Discrete Damage Modeling uses the Regularized eXtended Finite Element Method for the simulation of matrix cracking at initially unknown locations and directions independent of the mesh orientation. Cohesive interface model is used both for Mesh Independent Cracking as well as delamination propagation. The fiber failure mode is modeled by two different methods in tension and compression. Tensile failure is predicted by Critical Failure Volume criterion, which takes into account volumetric scaling of tensile strength. Compression fiber failure is simulated with a single parameter continuum damage mechanics model with non-compressibility condition in the failed region. Ply level characterization input data were used for prediction of notched and unnotched laminate strength. All input data required for model application is directly measured by ASTM tests except tensile fiber scaling parameter and compression fiber failure fracture toughness, which were taken from literature sources. The model contains no internal calibration parameters. Tensile and compressive strength of unnotched and open hole composite laminates IM7/977-3 has been predicted and compared with experimental data. Three different layups, [0/45/90/−45]2S, [30/60/90/−60/−30]2S, and the [60/0/−60]3S, were modeled and tested and showed good agreement with experiment in the case of tensile loading, whereas the compressive strength was generally under predicted for unnotched laminates and overpredicted for open hole laminates.

Correlation of acoustic emission with finite element predicted damages in open-hole tensile laminated composites

2017 ◽  
Vol 108 ◽  
pp. 427-435 ◽  
Author(s):  
Reza Mohammadi ◽  
Mehdi Ahmadi Najafabadi ◽  
Milad Saeedifar ◽  
Jalal Yousefi ◽  
Giangiacomo Minak
Keyword(s):  
Finite Element ◽  
Acoustic Emission ◽  
Laminated Composites ◽  
Open Hole
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