Structural Acoustic Problems With Absorbent Layers Within Laminated Composite Enclosures

2006 ◽  
Vol 128 (6) ◽  
pp. 705-712 ◽  
Author(s):  
Arup Guha Niyogi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Free Vibration ◽  
Laminated Composite ◽  
Transverse Shear Deformation ◽  
Element Formulation ◽  
Structural Damping ◽  
Element Analysis ◽  
First Order ◽  
Acoustic Domain

Studies on coupled structural acoustic problems within laminated composite enclosures are presented. Isoparametric quadratic boundary element formulation for the acoustic domain is coupled to the structural properties of the enclosure through mobility relations obtained from free vibration finite element analysis of the dry enclosure visualized as a folded plate with first order transverse shear deformation and rotary inertia. Velocity amplitudes and forcing frequency is specified over certain parts of the boundary. The rest is interactive boundary. Absorbent layers at the boundary are accommodated through admittance relation. Results show that impact of absorbent layers is frequency dependent while modifying structural damping has a better prospect.

Probabilistic Finite-Element Analysis of S2-Glass Epoxy Composite Beams for Damage Initiation Due to High-Velocity Impact

2016 ◽  
Vol 2 (4) ◽  
Author(s):  
Shivdayal Patel ◽  
Suhail Ahmad ◽  
Puneet Mahajan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Velocity ◽  
Laminated Composite ◽  
Composite Plates ◽  
High Velocity Impact ◽  
Element Analysis ◽  
Fiber Failure ◽  
Velocity Impact ◽  
Damage Initiation

The safety predictions of composite armors require a probabilistic analysis to take into consideration scatters in the material properties and initial velocity. Damage initiation laws are used to account for matrix and fiber failure during high-velocity impact. A three-dimensional (3D) stochastic finite-element analysis of laminated composite plates under impact is performed to determine the probability of failure (Pf). The objective is to achieve the safest design of lightweight composite through the most efficient ply arrangement of S2 glass epoxy. Realistic damage initiation models are implemented. The Pf is obtained through the Gaussian process response surface method (GPRSM). The antisymmetric cross-ply arrangement is found to be the safest based on maximum stress and Yen and Hashin criteria simultaneously. Sensitivity analysis is performed to achieve the target reliability.

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