Micro-macro Study On Detailed Model Of Composite Laminated Plates&Shells By Using Variational Asympototic Method

With the rapid development of space technology, the investigations on macroscopicproperties’ characterization and broken-down mechanism of composite materialstructures under elasticity condition are extremely desired.Anelastic model foranalyzing laminated composite plates under mechanical loadings is constructed by thevariational asymptotic method. The original3D nonlinear elasticity problem isformulated based on a set of intrinsic variables defined on the reference plane and forarbitrary deformation of the normal line. Then the variational asymptotic method is usedto rigorously split the3D problem into two problems: a nonlinear,2D, plate analysisover the reference plane to obtain the global deformation and a linear analysis throughthe thickness to provide the2D generalized constitutive law and the recovering relationsapproximate the original3D results. The uniqueness of asymptotic theory is to correctup to a certain order is used to cast the obtained asymptotically correct second-orderfree energy into a Reissner-Mindlin type model to account for transverse sheardeformation. Results from this theory for several cases have been compared with theexact elasticity solutions, classical lamination theory and first-order shear-deformationtheory to demonstrate the accuracy and power of the proposed theory.When we study the overall stress and strain of composite laminated plates, wewould need the virtual material properties of every layer board with relatively simplepopular method. When can build a virtual microscopic mechanics model from originalmaterials to obtain the equivalent homogeneous material properties, then we can furtherstudy the load response for the entire components of the composite materials under themechanical efforts. Multi-scale modeling and calculation can make more accuratecharacterization and prediction in material properties under certain load conditions, andit provides a strong support for material performance optimization.Multi-scale modeling and computation can characterize the performance ofcomposite materials and forecast certain conditions more accurately the response ofcomposite materials and structures; And it provides strong supports on the materialproperties of the micro-structure optimization, which can be used on multi-scalecalculations, preparation of materials before processing and microstructure design.Among the many cross-scales computing methods, variational asymptotic analysismulti-scale method is more genetic, efficient and accurate, which is applied to the periodic structure of composite materials characterization and structural analysis. Thebasic idea is the calculation and prediction of material properties along the microscopicto the macroscopic process, using the two-scale homogenization method, micro-scalesfrom a single package to calculate the performance parameters of homogenizedmacroscopic materials, while structural physics, mechanics calculation and prediction ofthe behavior of the mean field equations are calculated from the macro view. The use oftwo-scale variational asymptotic analysis method for the effective performance andresponse of composite laminates are characterized with dual-scale computing. Designand damage analysis method not only be able to consider the impact of themicrostructure on the macroscopic properties, but also be able to obtain macroscopicstress and the strain field in structural analysis, and we also can obtain microscopicstress and strain fields, which provide sufficient basis for the damage and fractureanalysis of composite structures. The method can be applied to engineering practice andpossesses great importance in theory.