Executive Summary : | Finite element software is essential during the design and analysis of complex systems. All the commercial FE software in India are externally sourced with high commercial and educational license fees, increasing with the number of users. The availability of the software is also subject to embargos. Hence, this led to development of indigenous software like FEASTSMT (STR TOOLS) by VSSC, ISRO. The objective of this proposal is to further enhance the functional capabilities of FEASTSMT by incorporating advanced modules deemed necessary for futuristic space technology applications. In particular, investigators propose following modules as per the immediate requirements of VSSC, ISRO: Contact module with isogeometric analysis (IGA) for numerical analysis of large deformation contact between two bodies both in two-and three-dimensions within the framework of nonlinear finite element method. A novel mortar variable-order (VO) non-uniform rational b-spline (NURBS) based discretization method, which encompasses both the traditional Lagrangian and the NURBS based IGA methods, will be employed. The accuracy and efficiency of the proposed VO method will be demonstrated through validation of a number of benchmarks problems and comparing obtained results with those from the literature. Acoustics Module for harmonic analysis of acoustic radiation and scattering. Investigators include problems both in interior and exterior domains. Our formulation will be capable of solving axi-symmetric problems using axi-symmetric elements besides general three dimensional problems with 3D elements. In exterior domain acoustic wave propagation, only outgoing acoustic waves are present. In outward wave favouring (OWF) strategy, they will use a special form of acoustic pressure which favours outgoing waves, but the final matrix will be of the same size, resulting in a marginal cost increase. Hyperelasticity for the general purpose finite element analysis (FEA) software – STR TOOLS, which lacks the module for simulating such hyperelastic materials. Various classes of material models – phenomenological, mechanistic and hybrid - will be used to model the mechanical behaviour of hyperelastic materials within both the updated and the total Lagrangian framework under varieties of loading scenarios. The addition of hyperelastic material modelling module will make the general purpose finite element analysis (FEA) software – STR TOOLS comprehensive and fit for usage by industry and academia. Operational modal analysis (OMA) for identifying the natural frequencies, damping and the mode-shapes of vibrating structures using both input-output and output-only multivariate data. OMA caters to the dynamic modelling and analysis of aerospace structures, in particular for FE-model updating. Eigensystem realization algorithm for input-output and blind source separation for output-only OMA are proposed. |