Thermal Buckling Behaviour of Thin and Thick Variable-Stiffness Panels

Abstract

The possibility of designing composite panels with non-uniform stiffness properties offers a chance for achieving highly-efficient configurations. This is particularly true for buckling-prone structures, whose response can be shaped through a proper distribution of the membrane and bending stiffnesses. The thermal buckling behaviour of composite panels is among the aspects that could largely benefit from the adoption of a variable-stiffness design, but, in spite of that, it has rarely been addressed. The paper illustrates a semi-analytical approach for evaluating the thermal buckling response of variable-stiffness plates (VSP) by considering different boundary conditions. The formulation relies upon the method of Ritz and a variable-kinematic approach, leading to a computationally efficient implementation, which is particularly useful for exploring the larger design spaces, typical of variable-stiffness configurations. Due to the possibility of choosing the underlying kinematic approach as an input of the analysis, the formulation is not restricted to thin plates, but is suitable for analyzing the response of thick plates as well. Novel results are derived, which can be useful for benchmarking purposes and for gathering insight into the mechanical behaviour of variable-stiffness plates. Furthermore, the importance of transverse shear flexibility is illustrated with respect to the boundary conditions as well as the degree of steering of the fibers.

Application of Rayleigh-Ritz formulation to thermomechanical buckling of variable angle tow composite plates with general in-plane boundary constraint

“…From Table. 4, it is clear that the results of critical buckling temperature predicted by using the present Rayleigh-Ritz model are very close to those obtained by Vescovini and Dozio[48] and Zhao et al[54] and FE solutions for all the composite materials studied. The ability of the proposed Rayleigh-Ritz model to accurately predict the thermal buckling response of VAT composite plates is thus demonstrated.…”

“…Recently, Haldar et al [47] extended the Rayleigh-Ritz minimization technique proposed by Dano and Hyer [22] to study thermally induced mul-tistable behavior of unsymmetric laminates with curvilinear fibre paths. Vescovini and Dozio [48] studied the thermal buckling of VAT composite plates in the framework of a variable-kinematics approach based on Carrera's Unified Formulation (CUF). In their work, closed-form solutions of prebuckling results are presented four different sets of inplane boundary constraints.…”

“…The results of critical buckling temperature obtained by the present Rayleigh-Ritz method for VAT composite plates made of different composite materials are listed in Table.4. The results published by Duran et al[50], Vescovini and Dozio[48] and Zhao et al[54] and FE solutions are also included for comparison purposes.…”

A semi-analytical approach for the analysis of variable-stiffness panels with curvilinear stiffeners

“…The advantages offered by VS laminates are well-known, and have been extensively studied with respect to their behavior in terms of mechanical buckling [1][2][3][4][5][6][7][8][9][10], thermal buckling [11][12][13], fundamental frequencies [14][15][16] and failure loads [5,17]. One side-effect of variable-stiffness configurations is the exponentially growing number of degrees of freedom, which requires special consideration.…”

Pre-buckling and Buckling Analysis of Variable-Stiffness, Curvilinearly Stiffened Panels

“…Potential gains offered by tow-steered panels are well-documented in the literature [1][2][3][4][5], and several studies clearly illustrated the possibility of improving buckling and postbuckling responses with respect to corresponding quasi-isotropic configurations. Recent works addressed also the effects of different kinematic theories when applied to the analysis of tow-steered panels [3,6,7]. In the past years, it was demonstrated that curvilinear stringers can be successfully used to further improve stiffness tailoring opportunities and, to a more general extent, the structural efficiency of stiffened panels.…”