Finite element analysis panels

Load and support conditions for individual components depend on the complete structure (or system) analysis, and are unknown to be determined in that analysis. For example, if a plastic panel is mounted into a much more rigid structure, then its support conditions can be specified with acceptable accuracy. However, if the surrounding structure has comparable flexibility to the panel, then the interface conditions will depend on the flexural analysis of the complete structure. In a more localized context, structural stiffness may be achieved by ribbing and relevant analyses may be carried out using available design formulae (usually for elastic behavior) or finite element analysis, but necessary anisotropy or viscoelasticity complicate the analysis, often beyond the ability of the design analyst. 

The edge effect can be evaluated, as a function of the panel size, the laminate structure and the aluminium thickness, by numerical methods, such as the Finite Element Analysis (FEA). 

A simple theoretical model based on composite beam theory associated with the traditional strength of the materials was developed to describe the behaviour of the panels in the elastic range. A three-dimensional finite elements analysis on the whole panel was also performed to simulate its flexural behaviour. 

A finite element analysis was performed for the overall behaviour in bending under actual conditions of support of the panel and for the compression test on the central longitudinal stiffener. Shell 63 elements (4 nodes, 6 dof s per node) were used to model the panel, and Beam 4 elements (2 nodes, 6 dof s per node) were used to model the brackets at the corners. The material properties used were those computed from the theory, taking into account the orthotropic features of the panel. The load applied for the simulation of the bending test was a pressure distributed on elements corresponding to the area in contact with the spreaders during the experiments. 

ERF are in the process of evaluating stress variations of panels under given loading conditions using finite element analysis techniques. 

This chapter presents the linear and non-linear dynamic finite element analysis intended to be used for nuclear facilities. Plasticity and cracking models are included. Solid isoparametric elements, panel and line elements are included which represent various materials. Solution procedures are recommended. Programs ISOPAR, F-BANG and other computer packages are recommend for the dynamic non-linear analysis of structures for nuclear facilities with and without cracking. 

There are many versions of software programs available for the analysis and design of composite laminates and laminated structural elements. ESAComp is one such version, initiated by the European Space Agency, covering fiber/matrix mechanics, plies, laminates, plates and stiffened panels, beams and columns, bonded joints and mechanical joints. The software can interface with the widely nsed finite element software packages. 

For finite element modeling of reinforced concrete wall segments subjected to nonlinear shear actions (e.g., squat walls, wall piers, wall spandrels), although a number of cyclic constitutive models have been proposed for simulating the nonlinear responses of constitutive panel elements of the finite element model, most of these model formulations are not included in commonly-used structural analysis platforms due to complexities in their implementation. A new constitutive... 

The methods discussed earlier are applied to the seat-occupant-restraint system of an aircraft. A description of a computer-aided analysis environment, including a multibody model of the occupant and a nonlinear finite element model of the seat, is provided, which can be used to re-construct variety of crash scenarios. These detailed models are useful in studies of the potential human injuries in a crash environment, injuries to the head, the upper spinal column, and the lumbar area, and also structural behavior of the seat. The problem of reducing head injuries to an occupant in case of a head contact with the surroundings (bulkhead, interior walls, or instrument panels), is then considered. The head impact scenario is re-constructed using a nonlinear visco-elastic type contact force model. A measure of the optimal values for the bulkhead compliance and displacement requirements is obtained in order to keep the possibility of a head injury as little as possible. This information could in turn be used in the selection of suitable materials for the bulkhead, instrument panels, or interior walls of an aircraft. The developed analysis tool also allows aircraft designers/engineers to simulate a variety of crash events in order to obtain information on mechanisms of crash protection, designs of seats and safety features, and biodynamic responses of the occupants as related to possible injuries. 

Use of impact sled tests is the most common technique for determining the postcrash dynamic behavior of an aircraft occupant. The impact sled and target tracking facilities available at National Institute for Aviation Research (NIAR) were used to conduct a study on occupant responses in a crash environment. Parallel analysis capabilities, including a multibody dynamic model of the occupant and a finite element model of seat structures, have been developed. The analysis has been used to reasonably predict the Head Injury Criteria (HIC) as compart with the experimental impact sled tests for an occupant head impacting a panel. A nonlinear viscoelastic contact force model was shown to better predict the experimental data on the contact forces than the Hertzian models. Suitable values of the coefficients in the contact force model were obtained and the correlations between the coefficients, HIC, and maximum deformation of the front panel were determined. A non-sled test method of pendulum-type has been designed to determine the head injuries as well as the performance of each particular impact absorber. 

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