Modelling the Effect of Microstructural Randomness on the Fracture of Composite Laminates with Stochastic Cohesive Zone Elements

2009 ◽  
Vol 417-418 ◽  
pp. 13-16
Author(s):  
Zahid R. Khokhar ◽  
Ian A. Ashcroft ◽  
Vadim V. Silberschmidt
Keyword(s):  
Cohesive Zone ◽  
Composite Laminates ◽  
Composite Structures ◽  
Laminated Composite ◽  
Specific Strength ◽  
Laminated Composite Structures ◽  
Structural Applications ◽  
Fibre Reinforced Polymer ◽  
Strength And Stiffness ◽  
Cohesive Zone Elements

Fibre reinforced polymer composites (FRPCs) are being increasingly used in structural applications where high specific strength and stiffness are required. The performance of FRPCs is affected by multi-mechanism damage evolution under loading which in turn is affected by microstructural stochasticity in the material. This means that the fracture of a FRPC is a stochastic process. However, to date most analyses of these materials have treated them in a deterministic way. In this paper the effect of stochasticity in FRPCs is investigated through the application of cohesive zone elements in which random properties are introduced. These may be termed ‘stochastic cohesive zone elements’ and are used in this paper to investigate the effect of microstructural randomness on the fracture behaviour of cross-ply laminate specimens loaded in tension. It is seen from this investigation that microstructure can significantly affect the macroscopic response of FRPC’s, emphasizing the need to account for microstructural randomness in order to make accurate prediction of the performance of laminated composite structures.

Influence of Z-Pinning on the Buckling of Composite Laminates under Edge-Wise Compression

2006 ◽  
Vol 312 ◽  
pp. 127-132 ◽  
Author(s):  
Wen Yi Yan ◽  
Hong Yuan Liu
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Laminated Composite ◽  
Initial Imperfection ◽  
Mode I ◽  
Theoretical Studies ◽  
Complete Understanding ◽  
Laminated Composite Structures ◽  
Mode Ii Fracture Toughness ◽  
Experimental And Theoretical Studies

Z-pinning is a newly developed technique to enhance the strength of composite laminates in the thickness direction. Recent experimental and theoretical studies have shown that z-pins significantly improve mode I and mode II fracture toughness. In practice, buckling accompanying delamination is a typical failure mode in laminated composite structures. For a complete understanding of the z-pinning technique towards improvements of the overall mechanical properties of laminated composites, a numerical model is developed in this paper to investigate the influence of z-pins on the buckling composite laminates with initial delaminations under edge-wise compression. The numerical results indicate that z-pinning can indeed effectively increase the compressive strength of the composite laminates provided that the initial imperfection is within a certain range. The magnitude of the improvement is consistent with available experimental data.

A Study of the Effect of Finite Element Meshing in the Modeling of Elastoplastic Degradation of Composite Laminates

2017 ◽  
Vol 14 (01) ◽  
pp. 1730001 ◽  
Author(s):  
S. Sadat ◽  
A. Mokaddem ◽  
B. Doumi ◽  
N. Benrekaa ◽  
A. Boutaous ◽  
...  
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Composite Structures ◽  
Laminated Composite ◽  
Mesh Size ◽  
Industrial Applications ◽  
Simulation And Optimization ◽  
Laminated Composite Structures ◽  
Finite Element Meshing ◽  
Good Agreement

Due to the increased use of composite materials in industrial applications, reliable and consistent finite element methods are required for the simulation and optimization of composite structures. In this paper, we presented the effect of finite element meshing in the modeling of degradation in composite structures under tensile stress; we have used an elastoplastic model to simulate the damage and plasticity behavior occurring in laminated composite structures carbon/epoxy: T300/914. This model works with different elements and the results obtained are not sensitive to mesh size. Thus, we have showed that two different meshes give the same results. Our findings are in good agreement compared to the experimental data.

Topology optimization of laminated composite structures under harmonic force excitations

2021 ◽  
pp. 002199832110526
Author(s):  
Zheng Hu ◽  
Shiping Sun ◽  
Oleksii Vambol ◽  
Kun Tan
Keyword(s):  
Topology Optimization ◽  
Composite Laminates ◽  
Composite Structures ◽  
Polynomial Interpolation ◽  
Excitation Frequency ◽  
Laminated Composite ◽  
Optimization Approach ◽  
Harmonic Force ◽  
Laminated Composite Structures ◽  
Analytical Sensitivities

In this paper, a topology optimization approach for the design of laminated composite structures under harmonic force excitations is proposed. A novel method is developed to calculate the harmonic response for composite laminates, which consists of two steps: firstly, based on the strain energy approach, the damping matrix model of composite laminates is established with the proportional damping assumption; then, the displacement response is calculated by the mode acceleration method The design objective of topology optimization is to minimize the displacement amplitude at the concerning point with an excitation frequency or a frequency band. An extended polynomial interpolation scheme is introduced to penalize the stiffness, damped stiffness and mass of elements. The analytical sensitivities of the objective and constraint functions to the density variables are derived in detail, and the globally convergent method of moving asymptotes is used to solve the optimization problem. Numerical examples are performed to demonstrate the effectiveness and feasibility of the proposed topology optimization method in improving the dynamic performance of laminated composite structures. The influence rules of excitation frequency and layer sequence on topologic shape are also discussed.

scholarly journals A model for fast delamination analysis of laminated composite structures

2020 ◽  
Vol 53 (2) ◽  
pp. 67-84
Author(s):  
Harri Katajisto ◽  
Petri Kere ◽  
Mikko Lyly
Keyword(s):  
Composite Structures ◽  
Laminated Composite ◽  
Strain Energy Release ◽  
Element Analysis ◽  
Geometrically Nonlinear Analysis ◽  
Shell Elements ◽  
Cycle Times ◽  
Modeling Methodology ◽  
Laminated Composite Structures ◽  
Cohesive Zone Elements

Delamination is one of the major failure mechanisms for composites and traditionally the simulation requires high expertise in fracture mechanics and dedicated knowledge of the Finite Element Analysis (FEA) tool. Yet, the simulation cycle times are high. Geometrically nonlinear analysis approach, which is based on the Reissner-Mindlin-Von K´arm´an type shell facet model, has been implemented into the Elmer FE solver. Altair ESAComp software runs the Elmer Solver in the background. A post-processing capability, which enables the prediction of the delamination onset from the FEA output, has been implemented into the AltairESAComp software. A Virtual Crack Closure Technique (VCCT) specifically developed for shell elements defining the Strain Energy Release Rate (SERR) related to the different delamination modes at the crack front is used. The onset of delamination is predicted using the relevant delamination criteria that utilize the SERR data and material allowables in the form of fracture toughness. The modeling methodology is presented for laminates including initial through-the-width delamination. Examples include delamination in the solid laminate and debonding of the skin laminate in the sandwich structure. Rather coarse FE mesh has proved to yield good results when compared to typical approaches that utilize the standard VCCT or Cohesive Zone Elements.

Recent Advances in Development and Processing of Titanium Aluminide Alloys

2000 ◽  
Vol 646 ◽  
Author(s):  
Fritz Appel ◽  
Helmut Clemens ◽  
Michael Oehring
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Environmental Stability ◽  
Physical Metallurgy ◽  
Specific Strength ◽  
Wide Range ◽  
Structural Applications ◽  
Strength And Stiffness ◽  
Nickel Base

ABSTRACTIntermetallic titanium aluminides are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently in use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. Some of these concerns are addressed in the present paper through specific comments on the physical metallurgy and technology of gamma TiAl-base alloys. Particular emphasis is placed on recent developments of TiAl alloys with enhanced high-temperature capability.

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