%0 Journal Article 
%A López Garrido, José Antonio
%T Análisis de material compuesto de matriz metálica mediante el método de elementos finitos

%D 2019
%U http://hdl.handle.net/10317/7708
%X The need for structural components with excellent specific stiffness and strength also at elevated temperatures results in high efforts in the development of advanced particle and fibre reinforced composites [Gadow, 2003]. With the focus on metallic matrices the highest potential to increase the specific mechanical properties are provided by fibre reinforcements. Misfits in thermal expansion coefficients lead to high normal and shear stresses at the interface, so that the mechanical properties of the composite can be reduced. During melt infiltration processes, in fibre reinforced performs, also the wettability plays a decisive role for optimized fibre incorporation [Whalen, 1975; Ebert, 1974]. Optimization of the interface means to provide sufficient fibre matrix bonding without damaging the fibres chemically or mechanically. The “solid-phase” techniques avoid fibre damage by chemical reactions, but the design of the component is strongly limited to extruded or rolled geometries [Ibe, 1994]. More complex geometries can be realized with liquid metal infiltrations but the preform positioning problems in the die and the need for high pressure resistance of the preform still limit the possible geometries. The main disadvantage of these “liquid–phase” techniques is the relatively long contact of the fibre with the melt resulting in significant fibre damage by chemical reaction at the interface. The use of laminates, consisting of metal sheets and woven fibre layers, in combination with thixoforging can solve this problem. The semi-solid state of the metal and the short forming times prevent chemical interaction with the fibres. The required globular microstructure of the metal phase for thixoforming can also be realized with thermal sprayed metal coatings on fibre fabrics [Siegert, 2004].
The thixoforging of continuous fibre reinforced components can be divided in 3 phases: Prepreg fabrication, prepreg heating and solidification of prepregs by thixoforging. In the first phase, thermally sprayed coatings on fibre fabrics are used to built-up the metal matrix. During thermal spraying a suitable microstructure for thixoforging is formed, similar to the procedure of spray forming [Moreno, 2006]. After laminating prepregs are reheated at temperature of thixoforging. After heating up, prepregs are placed in the heated die. To minimize the thermal shock effects due temperature difference between the heated prepreg and the die, the die temperatures ranges up to 450 ºC. Short time of production of thixoforging and the semisolid state of the metal matrix make sure the reduction of fibre damage at the interface between fibre and matrix metal. The high punch speed ensures the appropriate thixotropic behaviour of matrix material by preventing a precocious solidification due the heat transfer between the punch and the prepreg. The modellized process is a cooling in two phases of a thixoforged piece (figure 1) of 319 aluminium alloy reinforced with carbon fibre from near 600ºC until ambient temperature, 20 º C. In the first phase the ambient temperature is 450 ºC. Also, we compare the result with an alternative chilling process with a constant environment temperature of 20 ºC. The MMC analysis starts with a review of available literature, which provides a basic scheme to develop the methodology to prepare the models. These models will be run in order to obtain the stress field inside the material. These results allow us to evaluate different designs. The results will be compared with experimental tests in order to check the FEM models
%K Ingeniería Mecánica
%K Materiales
%K Materials
%K Ingeniería mecánica
%K Mechanical engineering
%K 3312 Tecnología de Materiales
%~ GOEDOC, SUB GOETTINGEN