Nomex

The aim of this thesis is to design and analyse an optimal lightweight chassis for the GUtech Shell Eco Marathon Team (GSET) prototype vehicle 2016. Considering the fact that increased weight has a detrimental effect on fuel economy, this thesis aims to aid the weight reduction objective set by GSET through designing a chassis that is lighter and stiffer than the previous year’s chassis. The overall proportions of the vehicle are also reduced by packaging the rear end in a more compact manner. Chassis design concepts are introduced and different composite materials are analysed. The newly designed composite chassis is modelled in Solidworks and then simulated in ANSYS Workbench Mechanical coupled with ANSYS Composite PrepPost using finite element analysis (FEA). Several possible loading scenarios are taken into consideration and then simulated in order to achieve the optimum compromise between low weight and adequate stiffness.

A sandwich panel structure utilising nomex and carbon fibre reinforced polymers (CFRP) is researched instead of a solely carbon fibre approach. The effect of increasing the sandwich core thickness is analysed using FEA. Furthermore an attempt to implement the engine as a chassis member is looked at with the final composite chassis design weighing in at less than half as much as the previous year’s aluminium chassis. A 55% weight reduction is achieved without compromising on stiffness and in the final chapter fabrication recommendations are provided that would be helpful for the next generation of GSET to fabricate the composite chassis in the University workshop.

Nomex honeycomb cores have been widely used in composite sandwich panels. To accomplish meso-scale finite element modeling of these cores, cell wall mechanical properties are required, for which limited data are available. In this work, tensile testing was performed on Nomex paper, phenolic resin, and Nomex paper coated with phenolic resin. Flatwise tension and compression tests were also performed on two types of Nomex honeycomb cores. Test results were calibrated in finite element modeling to account for strain gage local stiffening effects and thickness normalization. Identified cell wall material properties were implemented in a honeycomb core finite element model and further calibrated by matching simulation results to manufacturer test data. The cells’ double-wall thickness was also adjusted. These calibrations and adjustments led to an exact simulation match with test data. Numerically matching cell wall material properties depends on modeling sophistication and is subject to core test result variability and core construction differences among manufacturers.

A menudo, el fieltro punzonado presenta un tratamiento que le proporciona ciertas propiedades de permeabilidad, resistencia al desgarro, antiácido o antiadherencia, entre otras. Esta última es la más relevante para el fieltro punzonado utilizado en filtración industrial.

The aim of this thesis is to design and analyse an optimal lightweight chassis for the GUtech Shell Eco Marathon Team (GSET) prototype vehicle 2016. Considering the fact that increased weight has a detrimental effect on fuel economy, this thesis aims to aid the weight reduction objective set by GSET through designing a chassis that is lighter and stiffer than the previous year’s chassis. The overall proportions of the vehicle are also reduced by packaging the rear end in a more compact manner. Chassis design concepts are introduced and different composite materials are analysed. The newly designed composite chassis is modelled in Solidworks and then simulated in ANSYS Workbench Mechanical coupled with ANSYS Composite PrepPost using finite element analysis (FEA). Several possible loading scenarios are taken into consideration and then simulated in order to achieve the optimum compromise between low weight and adequate stiffness.

A sandwich panel structure utilising nomex and carbon fibre reinforced polymers (CFRP) is researched instead of a solely carbon fibre approach. The effect of increasing the sandwich core thickness is analysed using FEA. Furthermore an attempt to implement the engine as a chassis member is looked at with the final composite chassis design weighing in at less than half as much as the previous year’s aluminium chassis. A 55% weight reduction is achieved without compromising on stiffness and in the final chapter fabrication recommendations are provided that would be helpful for the next generation of GSET to fabricate the composite chassis in the University workshop.

This work is concerned with the finite element modeling of Nomex® honeycomb core and carbon/epoxy composite laminate face sandwich panel structures. One objective is the identification of a material model for the honeycomb's constituent material by model comparison with experimental test results. A detailed model of the panel structure, including the geometry of the honeycomb, was constructed. This model was loaded in the same fashion as corresponding 3-point flexion, 4-point flexion and compression experimental load tests. Linear isotropic and orthotropic Nomex® material models were evaluated by comparing simulation results with test results. Both the isotropic and orthotropic models can make the model agree reasonably well with 3-point flexion test results alone. When those 3-point flexion test identified material model parameters are used in the 4-point flexion and compression test models, they yield about 60% and 90% stiffer results than experiment, respectively. The modeling strategy used along with the material models evaluated thus provides unsatisfactory precision. The orthotropic material model nonetheless gave the best fit to experiments from the parameter sets evaluated.

Nomex™ honeycomb core composite sandwich panels are widely used in aircraft structures. Detailed meso-scale finite element modeling of the honeycomb geometry can be used to analyze sandwich inserts, vibration response, and complex combined loading cases. The accuracy of a meso-scale honeycomb modeling technique for static load cases was evaluated. A rectangular honeycomb core was modeled with perfect hexagon honeycomb cells. Compression and shear tests simulations with linear and non-linear solutions were performed for four core densities. The simulated moduli and buckling strengths were recorded. These results were compared to property data published by honeycomb manufacturers. The simulated maximum honeycomb wall stresses at the manufacturer predicted core strengths were also recorded. The honeycomb walls’ first compression deformation mode shape was observed. Sinusoidal small imperfections were then introduced in the honeycomb geometry based on that deformation mode shape. These imperfections provided a better match to manufacturer compressive modulus data while having a limited impact on the shear moduli. The simulated properties did not exactly match manufacturers’ shear and compression data together for all the core densities. Modeling the honeycomb cells with rounded corners and with increased thickness at the cell junctions are potential strategies to improve the accuracy.