Bending of cross-ply laminated composites: An accurate and efficient plate theory based upon models of Lekhnitskii and Ren

Origami-folding principles can be used with laminated composites to produce lightweight structures that are capable of drastic changes in shape. This paper presents a smart composite that can actively change its crease pattern to fold itself into different rigid shapes and provide a large range of motion. The composite uses a smart material with variable modulus sandwiched between two fiber-reinforced elastomeric skins, one of which is prestressed. Change in modulus of the sandwiched core layer allows prestress in the elastomeric skin to actuate the fold. Unfolding the structure to a flat shape can be accomplished through either embedded or external actuation. Passive composite panels were fabricated for model development and validation. An analytical model was developed based on classical laminate plate theory to study the influence of core modulus, core thickness, and elastomeric skin prestress on the equilibrium curvature of the composite structure. Selected smart materials that provide a change in modulus when stimulated are discussed as candidates for the core layer of the self-folding composite.

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Effect of Angle Ply On The Mechanical Performance of Jute Fibre Woven Mat /Epoxy Composites With Varying Ageing Conditions

10.21203/rs.3.rs-919614/v1 ◽

2021 ◽

Author(s):

Satheeshkumar S. ◽

Sathishkumar T. P ◽

Rajini Nagarajan ◽

Navaneethakrishnan P. ◽

Sikiru O. Ismail ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Plate Theory ◽

Laminated Composites ◽

Low Cost ◽

Laminated Plate ◽

Maximum Activation ◽

Mechanical Strengths ◽

Strength Retention ◽

Composite Samples

Abstract The present work investigates the mechanical strengths retention and prediction of maximum service life of sets of laminated composites by analyzing their diffusion coefficients and activation energies, using Fick’s law and Arrhenius principle. Jute fiber woven mat reinforced epoxy laminated composites (JFMRLCs) were prepared by simple hand lay-up and compression molding methods. The layering patterns of 0º balanced laminate of [0º/0º/0º/0º/0º], 30º angle-ply laminate of [0º/+30º/0º/-30º/0º] and 45° angle-ply laminate of [0°/+45°/0°/-45°/0°] were used to prepare the composite samples, according to classical laminated plate theory (CLPT). The composites were immersed in water at different periods of 10, 20, 30 and 40 days aging. The effects of the various periods of aging on their mechanical properties were studied. The results showed that the weights of the composite samples increased by increasing the aging periods. The mechanical properties of aged (wet) composites were compared with the unaged (dry) counterparts to predict their strengths retention. The composite with 45° layering pattern exhibited the maximum strength retention. Also, the same composite sample with layering pattern of 45° produced the maximum activation energy, based on Arrhenius principle. The tensile fractured surfaces were analyzed to investigate into their fiber-matrix interfacial bonds through images obtained from scanning electron microscopy (SEM). Summarily, it was evident that optimum JFMRLCs with layering pattern of 45° exhibited best mechanical properties. Hence, they can act as suitable, sustainable, low cost and environmentally friendly composite materials for structural marine and other related engineering applications.

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Topology optimization of compliant mechanisms with curvilinear fiber path laminated composites

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406215604878 ◽

2016 ◽

Vol 230 (17) ◽

pp. 3101-3110 ◽

Cited By ~ 4

Author(s):

Xinxing Tong ◽

Wenjie Ge ◽

Yonghong Zhang

Keyword(s):

Topology Optimization ◽

Strain Energy ◽

Compliant Mechanisms ◽

Plate Theory ◽

Laminated Composites ◽

Optimality Criteria ◽

Constitutive Relationship ◽

Laminated Plate ◽

Topology Optimization Problem ◽

Fiber Path

An approach for designing compliant mechanisms with curvilinear fiber path laminated composites is presented to obtain the optimum topology structure in this paper. A laminated plate with curvilinear fiber path is built by using the shifted fiber path method. Meanwhile, an equivalent constitutive relationship of the laminated plate has been obtained based on the laminated plate theory. Taking the element relative density as design variable, minimizing the weighted linear combination of the mutual strain energy and the strain energy is considered as an objective function to achieve the desired deformation and enough load-carrying capacity of compliant mechanisms with the volume constraint. The topology optimization problem is solved via the optimality criteria and the sensitivity filtering technology. The numerical examples of designing compliant inverters are investigated to demonstrate the effectiveness of the proposed method. And furthermore, the displacements and the stress levels are also discussed for the compliant inverters with different curvilinear fiber laminated sequences.

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