A new model is proposed to accurately predict the wrinkling and collapse loads of a membrane inflated beam.In this model,the pressure effects are considered and a modified factor is introduced to obtain an accurate prediction.The former is achieved by modifying the pressure-related structural parameters based on elastic small strain considerations,and the modified factor is determined by our test data.Compared with previous models and our test data,the present model,named as shell-membrane model,can accurately predict the wrinkling and collapse loads of membrane inflated beams.
Wrinkling analysis of a rectangular membrane with a single crease under shearing is performed to understand the wrinkle-crease interaction behaviors.The crease is considered by introducing the residual stresses from creasing and the effective modulus into the baseline configuration with assumed circular cross-sectional crease geometry.The wrinkling analysis of the creased membrane is then performed by using the direct perturb-force(DP) simulation technique which is based on our modified displacement components(MDC) method.Results reveal that the crease may influence the stress transfer path in the membrane and further change the wrinkling direction.The crease appears to improve the bending stiffness of the membrane which has an effective resistance on the wrinkling evolution.The effects of the crease orientation on wrinkle-crease interaction are studied toward the end of this paper.The results show that the wrinkling amplitude,wavelength,and direction increase as the crease orientation increases,and the wrinkling number decreases with the increasing crease orientation.These re-sults will be of great benefit to the analysis and the control of the wrinkles in the membrane structures.
C.-G.Wang.H.-F.Tan.X.-D.He Center for Composite Materials,Harbin Institute of Technology,150080 Harbin,China Post-doctoral Research Center in Material Science and Engineering,Harbin Institute of Technology,150001 Harbin,China
This paper extends Le van's work to the case ofnonlinear problem and the complicated configuration. Thewrinkling stress distribution and the pressure effects are alsoincluded in our analysis. Pseudo-beam method is presentedbased on the inflatable beam theory to model the inflatablestructures as a set of inflatable beam elements with a pre-stressedstate. In this method, the discretized nonlinearequations are given based upon the virtual work principlewith a 3-node Timoshenko's beam model. Finite elementsimulation is performed by using a 3-node BEAM 189 elementincorporating ANS YS nonlinear program. The pressureeffect is equivalent included in our method by modifyingbeam element cross-section parameters related to pressure.A benchmark example, the bending case of an inflatable cantileverbeam, is performed to verify the accuracy of our proposedmethod. The comparisons reveal that the numericalresults obtained with our method are close to open publishedanalytical and membrane finite element results. The methodis then used to evaluate the whole buckling and the load-carryingcharacteristics of an inflatable support frame subjectedto a compression force. The wrinkling stress and regioncharacteristics are also shown in the end. This method givesbetter convergence characteristics, and requires much lesscomputation time. It is very effective to deal with the whole load-carrying ability analytical problems for large scaleinflatable structures with complex configuration.
Changguo Wang Huifeng Tan Xingwen Du Center for Composite Materials,Harbin Institute of Technology, 150001 Harbin, China
