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In the lightweight design of aircraft, spacecraft and marine vessels, often advanced materials are utilised. Advanced materials such as laminated composites made of fibre‐reinforced plastics show transverse shear deformations if they are considered “thick” or possess little transverse shear stiffness. In most cases, the effect of the shear deformations is neglected, and few computational models exist...
The local stability of unsymmetric laminated structures is significantly affected by bending‐extension coupling and the comparatively low transverse shear stiffnesses, which have to be included in the structural analysis. If such structures have flat surfaces in segments, they can be investigated with the discrete plate analysis. In this analysis, the individual segments are considered as plates with...
The development of efficient computational models for the accurate prediction of the state variables in general composite laminated shells undergoing uniform edge loadings is a major challenge, especially when stress concentration phenomena such as the free‐edge effect have to be considered. This paper addresses this issue by introducing a higher‐order semi‐analytical approach for the assessment of...
The local stability of thin‐walled fibre‐reinforced plastic composite beams can be reduced to individual laminates using discrete plate theory. These individual plates receive a supporting effect from their surrounding structure, which is modelled with rotational restraints. In the present investigation, this buckling problem is described by a closed‐form solution. The energy‐based method works with...
Typical thin‐walled structures are found in applications like aircraft, spacecraft and marine vessels. For this type of structure, stability behaviour is crucial. The better this behaviour is understood, the better the full lightweight potential can be exploited. For composite structures especially, new fast analysis tools for preliminary design are required to address this issue. Therefore, the local...
The design freedom provided by additive manufacturing offers new opportunities to fabricate novel structures with a high lightweight potential, such as strut‐based lattice structures. These lattice structures consist of periodically repeated unit cells and can be used in several applications due to their outstanding mechanical performance. One of the possible applications are cores of sandwich panels...
Currently, the application of composites in aerospace parts exposed to higher temperatures and in aggressive media is still severely limited. To replace metal alloys, alternative resins systems with suitable long‐term heat resistance are needed. In this study, the effect of the aviation hydraulic fluid Skydrol on the thermal and mechanical properties of a high‐Tg, anhydride‐cured epoxy resin in the...
In this paper a semi‐analytical approach is developed which enables the computation of the stress field in the vicinity of a transverse crack in symmetric cross‐ply laminated plates subjected to an in‐plane tensile load. Due to the assumption of a plane state of strain, the analytical model can be reduced to a two‐dimensional plate strip. After a discretization of the considered laminate into mathematical...
The stability behavior is critical for thin‐walled composite structures. This type of structures is for example employed in aircraft, spacecraft and marine vessels, where weight is an important factor in the design. For stiffened panels of, e.g. a fuselage structure, shear is a relevant load case. A new approximate computational model for the local buckling behavior of omega‐stringer‐stiffened panels...
The present work deals with the semi‐analytical assessment of the three‐dimensional stress fields in circular cylindrical symmetrically and unsymmetrically laminated cross‐ply shells undergoing different transverse loads. Starting from a closed‐form plane‐strain analysis in the innermost regions of the laminated shell, the elasticity solution is upgraded by a higher‐order displacement‐based approach...
Buckling of shear‐deformable laminated plates is investigated in the present study. A closed‐form method to determine the buckling load is developed within the framework of Reddy's Third Order Shear Deformation Theory (TSDT). The considered orthotropic plates are under uniaxial compression and simply supported at all edges with rotational restraints at the unloaded edges. This allows the modelling...
Due to their high mechanical performance, sandwich panels are widely utilized in many applications. Among the most frequently used cores in sandwich panels are honeycomb structures. Since the invention of additive manufacturing, new core structures like strut‐based lattices which are not possible by conventional manufacturing processes are also being considered as cores for sandwich panels. Depending...
Technical elastomers are usually quasi‐incompressible. For simulations they are, therefore, often modeled as ideal incompressible hyperelastic materials, or a linear relation between the hydrostatic pressure and the (volumetric) dilation is assumed, i.e., a linear compression model with constant bulk modulus is used. However, for strongly compressed structural components, like sealings or damper elements,...
The present work deals with the semi‐analytical assessment of the three‐dimensional stress fields in cylindrically curved symmetrically and unsymmetrically cross‐ply laminated shells subjected to bending load. The developed approach incorporates a layerwise plane‐strain analysis in the innermost regions of the shell. The closed‐form ‘inner solution’, further on, is upgraded by a displacement‐based...
The reduced bending stiffness method is used in the framework of computational models for stringer stiffened panels. Here, the stringer foot is often stacked on top of the skin of the panel and leads to a stacked laminate with extensional bending stiffness coupling. The validity of the reduced bending stiffness method for the mentioned laminate type is investigated and assessed, as only unsymmetrical...
Technical elastomers are usually quasi‐incompressible. For simulations they are, therefore, often modeled as ideal incompressible or a linear relation between the hydrostatic pressure and the (volumetric) dilation is assumed, i.e., a constant bulk modulus. However, for strongly compressed structural components, like sealings or damper elements, a nonlinear material model for the compression behavior...
This paper considers the buckling of transverse shear‐deformable orthotropic laminated plates under uniaxial compression, which is modeled with the third‐order shear deformation theory (TSDT). The consideration of transverse shear deformation is relevant for plates with small transverse shear stiffness or small length to thickness ratio. The supporting effect of the surrounding structure is represented...
This paper presents a semi‐analytical method for the mixed‐mode buckling problem of composite beams, i.e. the interaction between the local buckling modes of the segments of shear deformable symmetrically laminated composite I‐beams. The buckling analysis employs Reddy's third‐order shear deformation theory and the Ritz‐method in conjunction with adequate series expansions for the buckling degrees...
A semi‐analytical analysis method for displacements, strains and stresses in laminated composite plates with local reinforcement by patches/doublers is presented. The analysis approach is based on a “global” solution provided by the Classical Laminate Plate Theory (CLPT). Further, a “local” model is introduced which discretizes each laminate ply into several mathematical layers. For each of these...
The present work deals with the local buckling of thin‐walled composite‐beams with I, Z, C, L and T‐cross‐sections under axial load. In this study the analysis of the buckling load of the complete composite‐beam is performed using the Ritz‐method. The individual webs and flanges of the beam are assembled by suitable continuity conditions in one system. In order to achieve that, new displacement shape...
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