Simulations of Delamination Propagation in Composite Laminates under Static and Low-Velocity Impact Transverse Loads Using a New Cohesive Model

2008 ◽  
Vol 32 ◽  
pp. 137-140
Author(s):  
Ning Hu ◽  
Yutaka Zemba ◽  
Hisao Fukunaga
Keyword(s):  
Composite Laminates ◽  
Time Integration ◽  
Low Velocity Impact ◽  
Integration Scheme ◽  
Initial Stiffness ◽  
Low Velocity ◽  
Cohesive Model ◽  
Transverse Loads ◽  
Time Integration Scheme ◽  
Set Up

In this paper, we have proposed a new cohesive model to stably and accurately simulate delamination propagations in composite laminates under transverse loads. In this model, we set up a pre-softening zone in front of the original softening zone. In this pre-softening zone, the initial stiffness is gradually reduced as the interface strength decreases. However, the onset displacement for starting the real softening process is not changed in this model. The fracture toughness of materials for determining the final displacement of complete decohesion is not changed too. This cohesive model is implemented in the explicit time integration scheme. A DCB problem is employed to analyze the characteristics of the present cohesive model. Moreover, an experimental example of laminates under impact loads is employed to illustrate the validity of the present method.

Numerical Simulation of Compressive Residual Strength for Damaged Composite Laminates

2012 ◽  
Vol 525-526 ◽  
pp. 385-388
Author(s):  
Tian Jiao Qu ◽  
Xi Tao Zheng ◽  
Di Zhang
Keyword(s):  
Composite Laminates ◽  
Impact Test ◽  
Compressive Load ◽  
Low Velocity Impact ◽  
Fiber Breakage ◽  
Low Velocity ◽  
Appearance Time ◽  
Finite Element Software ◽  
Set Up ◽  
Good Agreement

After the low-velocity impact test of composite laminates of T800/BA9916, CAI test and compression test of laminates with a hole have been carried out. Two types of models were set up by the finite element software ABAQUS respectively. The FEA results were good agreement with the testing results. The investigation of models with a hole indicates that the appearance time of ultimate compressive load is earlier than that of fiber breakage expanding to boundary. Moreover, the diameter and the depth of blind hole significantly influence the ultimate compressive load.

Effect of oblique angle on low velocity impact response of delaminated composite conical shells

2014 ◽  
Vol 228 (15) ◽  
pp. 2663-2677 ◽  
Author(s):  
Sudip Dey ◽  
Amit Karmakar
Keyword(s):  
Time Integration ◽  
Impact Angle ◽  
Oblique Impact ◽  
Dynamic Responses ◽  
Hertzian Contact ◽  
Low Velocity Impact ◽  
Integration Scheme ◽  
Element Formulation ◽  
Low Velocity ◽  
Conical Shells

This paper presents the effect of oblique impact angle on low velocity transient dynamic responses of delaminated composite pretwisted shallow conical shells. An eight-noded isoparametric quadratic plate bending element is employed in the finite element formulation incorporating rotary inertia and effects of transverse shear deformation based on Mindlin’s theory. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time-dependent equations are solved by Newmark’s time integration scheme. A comparative study is carried out on torsion stiff, cross-ply, and bending stiff laminates to investigate the effects of triggering parameters like angle of twist, plate displacement, striker’s velocity, and displacement for graphite-epoxy composite laminate subjected to low velocity oblique impact at the center.

scholarly journals Structural Reliability Sensitivities under Nonstationary Random Vibrations

2013 ◽  
Vol 2013 ◽  
pp. 1-21 ◽  
Author(s):  
Rita Greco ◽  
Francesco Trentadue
Keyword(s):  
Structural Reliability ◽  
Structural Parameters ◽  
Time Integration ◽  
Structural Response ◽  
Integration Scheme ◽  
Structural Systems ◽  
Frame Building ◽  
Time Integration Scheme ◽  
Noise Input ◽  
The Time Domain

Response sensitivity evaluation is an important element in reliability evaluation and design optimization of structural systems. It has been widely studied under static and dynamic forcing conditions with deterministic input data. In this paper, structural response and reliability sensitivities are determined by means of the time domain covariance analysis in both classically and nonclassically damped linear structural systems. A time integration scheme is proposed for covariance sensitivity. A modulated, filtered, white noise input process is adopted to model the stochastic nonstationary loads. The method allows for the evaluation of sensitivity statistics of different quantities of dynamic response with respect to structural parameters. Finally, numerical examples are presented regarding a multistorey shear frame building.

Low Velocity Impact Response of Composite/Sandwich Structures

2016 ◽  
Vol 725 ◽  
pp. 127-131 ◽  
Author(s):  
Kumar V. Akshaj ◽  
P. Surya ◽  
M.K. Pandit
Keyword(s):  
Sandwich Structures ◽  
Weight Ratio ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Core Material ◽  
Design Parameters ◽  
Low Velocity ◽  
Velocity Impact ◽  
Composite Sandwich ◽  
Set Up

Dent resistance of structures is one of the important design parameters to consider in automotive, aerospace, packaging and transportation of fragile goods, civil engineering and marine industries. It is important to study the dynamic impact response of various combinations of skin and core materials which can provide desired fracture toughness and highest strength to weight ratio for such applications. This paper discusses the low velocity impact response of sandwich structures having unique combination of mild steel as skin material bonded to thermoplastics/PU foam as core material. HDPE, LDPE and polypropylene were the choice of thermoplastics and an optimum combination of materials for the sandwich structure was evaluated using drop-weight experimental set up. It is observed that LDPE is the best choice of core material for the sandwich structures considered.

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