Frantisek Sedlacek

Additive Manufacturing of PA6 with Short Carbon Fibre Reinforcement Using Fused Deposition Modelling

The aim of this research was to determine the influence of the short carbon fibres in nylon PA6 polymer used for fused deposition modelling (additive manufacturing) technology. Specimens from pure PA6 and PA6 with short carbon fibres were fabricated, with both main directions of the material with respect to the build orientation in a 3D printer. Experimental tensile tests of the specimens were carried out at several temperatures according to ISO standards. The strength, tensile modulus and ductility in relation to the temperature were compared. A significant influence of the short carbon fibres on the strength and heat deflection temperature of the part was found in PA6 and also for the orientation of the build in the 3D printer.

Optimization of Additive Manufactured Components Using Topology Optimization

Additive manufacturing (AM) is today one of the fastest growing industries. Previously, this technology was called Rapid Prototyping. The term ‘rapid prototyping’ (RP) was used in a variety of industries to describe a process for rapidly production of parts before final release or commercialization [1]. Today, this term is not current, because now 3D printing is not used only for fabricating prototypes, but it is increasingly used for small-series production of final parts. This leads to higher requirements on sufficient strength and stiffness of these parts. This problem can be solved using advanced numerical simulations, which also allows to found appropriate solution in combination with structural optimizations. There are many types of structural optimizations (such as geometry, topography, topometry, shape or topology optimization). Topology optimization is one of the best optimizations for this purpose because it can find the best use of material within a given design space [2]. Its use is often overlooked because the final optimized shape of the part is often too complicated for conventional manufacturing technologies, but it is not for AM technologies.

Dimension Stability of Thin-Walled Parts from 3D Printed Composite Materials

3D print of composite materials is one of the rapidly developing areas of additive manufacturing technology. This technology is using (instead of advanced FDM or SLA technologies) materials reinforced by short or micro fibres (mainly carbon or glass fibres). These fibres are oriented mainly in direction of filament extrusion. This is causing transverse- isotropic mechanical properties of final part. Composite materials with short fibres has higher modulus of elasticity, higher strength in bending, better thermal stability and higher impact resistance. These properties can be defined by change of volume rate between matrix and reinforcement. It is noticed nowadays, that these materials are more used in automotive and aerospace industry.

STRENGTH ANALYSIS OF PIN CONNECTIONS USING COMPUTER AIDED SYSTEMS

emphasis is given to accurate prediction of their properties, especially strength. There are several options for predicting pin connections, such as analytical calculations, Special-Purpose Programs (SPPs), or Finite Element Analysis (FEA). Nowadays companies do not usually have all these prediction methods available. The main reason is price and the maintenance of the software. In particular, smaller companies are usually equipped with SPPs [MITCalc 2003-2013, KISSsoft AG 1998-2014, BSPOJ 1992] based on spreadsheets or databases, because FEA is less affordable and is a time consuming process. Consequently, they have no other choice but to accept the information and values obtained from these SPPs, even without understanding their principles. This scientific work describes the comparison of the prediction methods of the pin connections so that the results should be usable for designers in the evaluation of similar connections. One section of this paper is devoted to comparing the programs with respect to material parameters, types of loading, evaluation criterions and results. A detailed comparison was undertaken for a specific connection using securing pins between two steel boards. This work is a continuation of the scientific work [Lasova 2015], where the capabilities of FE method and SPPs in evaluation of gears were compared.

Optimal design of a composite bellows coupling using a structural optimization

This paper deals with a flexible bellows coupling from composite materials that may be used as a replacement for some conventional rigid steel couplings. A geometry optimization was done in connection with structural analysis to find the optimal geometry and layout of the individual plies of the laminate of the composite bellows coupling. These numerical simulations were created with NX Nastran solver in Siemens Simcenter 11. An advanced FE model was used to verify the model according to the geometry optimization. A maximum stress strength criterion was carried out to evaluate the strength of the composite structure.

Design and optimization of composite parts using numerical simulations

The article deals with the use of numerical simulations for the design and optimization of parts with complicated shapes made from composite materials. An airbox designed for a light single-seat racing car was chosen as a representative example. The numerical analysis is primarily focused on the maximum reduction of the mass of the component while retaining adequate stiffness and strength and also taking into account the manufacturing technology of the component. Carbon composite fabrics in combination with high performance epoxy resin were used to ensure the maximum stiifness of the part. In order to ünd the best option, an advanced CAE simulation based on the Finite Element Method was used with a special module designated directly for creating models from alternative materials. Zone-based and ply-based FE models were created to find the optimal layout of the individual plies of the laminate. Maximum stress failure criterion was used to evaluate the strength of the part. A 3D model for the numerical simulation follows all the layers of the composite materials, including cuts, notches, resin drops and precise calculation of the main directions of the fibres and their distortion or overlap caused by more complex shaped surfaces.

Strength Determination of Composite Flexible Joint

This thesis deals with the design of a joint for composite flexible elements using an integrated connection. For the verification of the selected layout, a wrapping loop was chosen as a simplified member, which was created on a special form designed for these samples. The material used was unidirectional fibreglass and epoxy resin. These samples were then compared using quasi-static tensile and compression tests. The tests were carried out with the Zwick-Roell Z050 machine. The resulting data of the experiment were then compared with the data obtained from numerical simulations using the finite element system Siemens NX 10 and SIMULIA Abaqus 6.13. 3D strength criteria Maximum stress and direct-mode strength criterion LaRC04 were used for evaluation.