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Experimental and numerical investigation of a multi-step thermoplastic pultrusion process.
The objective of this thesis is to compare a multi-stage pultrusion set up against a single stage and investigate its potentials on an experimental and numerical level from manufacturing and material property perspectives
Thermoplastic pultrusion is one of the most promising manufacturing techniques for high quality, high perfor-mance composites at a competitive cost. In this joint re-search project with the Swiss industry, a novel pultrusion concept has been developed at CMASLab, which is cur-rently able to manufacture rods up to up to Ø20mm. As the current process consists of melting polymer fibres mixed with reinforcing fibres in a circular die to impregnate the material and then cool the composite rod from outside until solidification, large residual stresses are expected to occur in the material for larger rod diameters up to Ø 100mm. This could lead to cracks or other defects in the material. To overcome those challenges, new manufacturing concepts need to be developed to reduce the cooling time and the effects related to thermal gradients. One concept consists of a multistage pultrusion process, where layers of additional material are deposited onto an already consolidated rod, to reduce cooling time, but also decrease the residual stresses inside the material (see Fig. 3) A first prototype die for this process has been developed in a bachelor thesis by Jonas Keller. Although the idea was proven to work, the temperatures inside the rod after the first stage reached the melting point when entering the second stage and therefore missed the goal to reduce the cooling effort for the pultruded profile. The goal of this thesis is to optimize the existing multistage set up and compare it with the single stage process to effectively highlight its advantages and shortcomings.
Thermoplastic pultrusion is one of the most promising manufacturing techniques for high quality, high perfor-mance composites at a competitive cost. In this joint re-search project with the Swiss industry, a novel pultrusion concept has been developed at CMASLab, which is cur-rently able to manufacture rods up to up to Ø20mm. As the current process consists of melting polymer fibres mixed with reinforcing fibres in a circular die to impregnate the material and then cool the composite rod from outside until solidification, large residual stresses are expected to occur in the material for larger rod diameters up to Ø 100mm. This could lead to cracks or other defects in the material. To overcome those challenges, new manufacturing concepts need to be developed to reduce the cooling time and the effects related to thermal gradients. One concept consists of a multistage pultrusion process, where layers of additional material are deposited onto an already consolidated rod, to reduce cooling time, but also decrease the residual stresses inside the material (see Fig. 3) A first prototype die for this process has been developed in a bachelor thesis by Jonas Keller. Although the idea was proven to work, the temperatures inside the rod after the first stage reached the melting point when entering the second stage and therefore missed the goal to reduce the cooling effort for the pultruded profile. The goal of this thesis is to optimize the existing multistage set up and compare it with the single stage process to effectively highlight its advantages and shortcomings.
The objective of this thesis is to investigate the potential of the multistage pultrusion process through an experimental and numerical approach. The first part will consist of the study of different processing parameters (e.g. pulling speed) and material properties (e.g. void content). The second part will consist of a simulation study to confirm the results of the first part and provide a general conclusion about different diameter combinations.
Tasks:
-Experimental study of processing parameters
-Investigation of material parameters
-Development and build of Ø5 mm pultrusion diameter die
-Modification of FEM-models to validate the experi-mental studies
The content as well as starting dates can be discussed to suit a Masters, Semester or Bachelor thesis as well as the personal interests of the student.
The objective of this thesis is to investigate the potential of the multistage pultrusion process through an experimental and numerical approach. The first part will consist of the study of different processing parameters (e.g. pulling speed) and material properties (e.g. void content). The second part will consist of a simulation study to confirm the results of the first part and provide a general conclusion about different diameter combinations.
Tasks:
-Experimental study of processing parameters
-Investigation of material parameters
-Development and build of Ø5 mm pultrusion diameter die
-Modification of FEM-models to validate the experi-mental studies
The content as well as starting dates can be discussed to suit a Masters, Semester or Bachelor thesis as well as the personal interests of the student.
Maximilian Volk
CMASLab ETZ Zürich
LEE O 225
+41446326548
mvolk@ethz.ch