Francesco Cosco

Concept Modelling of Vehicle Joints and Beam-Like Structures through Dynamic FE-Based Methods

This paper presents dynamic methodologies able to obtain concept models of automotive beams and joints, which compare favourably with the existing literature methods, in terms of accuracy, easiness of implementation, and computational loads. For the concept beams, the proposed method is based on a dynamic finite element (FE) approach, which estimates the stiffness characteristics of equivalent 1D beam elements using the natural frequencies, computed by a modal analysis of the detailed 3D FE model of the structure. Concept beams are then connected to each other by a concept joint, which is obtained through a dynamic reduction technique that makes use of its vibration normal modes. The joint reduction is improved through the application of a new interface beam-to-joint element, able to interpolate accurately the nodal displacements of the outer contour of the section, to obtain displacements and rotations of the central connection node. The proposed approach is validated through an application case that is typical in vehicle body engineering: the analysis of a structure formed by three spot-welded thin-walled beams, connected by a joint.

Improved human-computer interaction for mechanical systems design through augmented strain/stress visualisation

Strain/stress evaluation is a crucial operation performed during severa l stages in the typical mechanical product development/life cycle. Howeve r it is often difficult to obtain an appropriate estimation of the strain and stress distribution due to the difficult to model operational conditions, unknown inp ut forces and/or parameters. This makes it particularly difficult for a des ign r to evaluate whether the final product under testing meets all the operationa l design specifications. This work presents an extended Kalman filtering ap proach to obtain accurate strain and stress estimates of a structure under operatio nal loading. This information is exploited in an augmented reality application to visualize strains and corresponding stresses on a real component. Th is provides a very efficient human-computer interface to evaluate strains and stres ses on a physical prototype. This approach is therefore very suitable to improv e the design of components due to the good overview of the performance. In order to obtain an efficient formulation, the developed approach is based on the exploitation of reduced order mechanical models based on high fidelity fin eelement design models. By including a parameterization in the reduced mod el, the approach can be made robust with respect to unknown operational pa rameters, like boundary conditions. The obtained paradigm is validated on a flexible beam with unknown input forces and length. The proposed approach permits a m ore natural visualization and interpretation of operational conditions. Our results enco urage the adoption of the proposed approach not only for design validation but also on-line monitoring of structural components, opening new possibility in the fi eld of Augmented Reality for Maintenance. Copyright

An extended Kalman filter approach for augmented strain/stress visualization in mechanical systems

This work presents an extended Kalman filtering approach to obtain accurate strain and stress estimates of a structure under operational loading. This information is exploited in an augmented reality application to visualize strains and corresponding stresses on a real component. A parametrized reduced physical model allows an efficient computation of the stresses in the Kalman filter. The model is parametrized in order to give good robustness to uncertain parameters, by estimating the parameters concurrently with the states. In order to allow unknown loading conditions, also the unknown input forces are estimated. This approach offers a very efficient and robust estimation approach. On the other side, using augmented reality as the visualization paradigm, offers two major benefits: visualizing operational strains and stresses field instead of discrete quantities; collocating the results on top of the real component under investigation. The obtained paradigm, validated with a demonstration case through an experimental validation on a beam, permits a more natural visualization and interpretation of operational conditions. Our results encourage the adoption of the proposed approach for on-line monitoring of structural components, opening new possibility in the field of Augmented Reality for Maintenance.