Experimental investigation on dry or impregnated tow mechanical behaviour under multiaxial loads
Topic(s) : Material science
Co-authors :
Alexandre GUILLOUX (FRANCE), Julien VALETTE (FRANCE), Arnaud GILLET (FRANCE), Jules BAILLY (FRANCE)Abstract :
Filament Winding and Pultrusion are industrial processes for manufacturing composite with a very good repeatability. With a high level of automation, they allow short processing time while achieving high level of fibre volume fraction.
The main difficulty is to tune their operative parameters such as tow tension, delivery speed of those tows, temperature…in order to achieve the desired quality of the composite.
The use of numerical simulation is then mandatory to forecast the progress of such process in terms of its physical phenomenon: thermal, chemical and mechanical. Those tools allow to follow the state of the component, fibre and matrix, at the various stage of the process. Thus they are a useful help to optimize the final composite structure both in terms of mechanical behaviour: ultimate, fatigue… and in terms of economical criterion: production rate, material consumption… However they require to have access to the proper mechanical behaviour of fibres and tows at all process conditions stages.
The majority of the experimental work is based on uniaxial, longitudinal tensile [1] or transversally compressive [2] tests, and, most often on reinforcements, i.e. structured tows in a textile frame, with some post processing [3]. Very few studies have been devoted to the behaviour of fibre tow under multiaxial loading induced by manufacturing processes [4]. Indeed, the tows are simultaneously under tension while being compressed by tooling (pultrusion process) or by other tow (filament winding).
To observe those various behaviour, the authors have designed and manufactured a multiaxial test bench, allowing to properly load a fibre tow while measuring its transversal deformations.
Fig. 1. Experimental bench schematic.
The device allows to measure deformations in the plane orthogonal to the tow axe (fig 1). It has been used to investigate the influences of tow tension and saturation level on the tow transversal behaviour (fig2). Different types of tow, defined by their transversal geometry and filament count, have been analysed. The variability of the tow dimensions among a given type has also been quantified. Various load factors have been applied with and without impregnated tow with different fluids.
Fig. 2. Thickness (a) and width (b) of dry tow, function of compaction for different tension.
The influences of the combinations of the tested variables are quantified using different methods and provide the basis for a set of key parameters for behavioural modelling, to be applied to the simulation of the processes mentioned above.
The main difficulty is to tune their operative parameters such as tow tension, delivery speed of those tows, temperature…in order to achieve the desired quality of the composite.
The use of numerical simulation is then mandatory to forecast the progress of such process in terms of its physical phenomenon: thermal, chemical and mechanical. Those tools allow to follow the state of the component, fibre and matrix, at the various stage of the process. Thus they are a useful help to optimize the final composite structure both in terms of mechanical behaviour: ultimate, fatigue… and in terms of economical criterion: production rate, material consumption… However they require to have access to the proper mechanical behaviour of fibres and tows at all process conditions stages.
The majority of the experimental work is based on uniaxial, longitudinal tensile [1] or transversally compressive [2] tests, and, most often on reinforcements, i.e. structured tows in a textile frame, with some post processing [3]. Very few studies have been devoted to the behaviour of fibre tow under multiaxial loading induced by manufacturing processes [4]. Indeed, the tows are simultaneously under tension while being compressed by tooling (pultrusion process) or by other tow (filament winding).
To observe those various behaviour, the authors have designed and manufactured a multiaxial test bench, allowing to properly load a fibre tow while measuring its transversal deformations.
Fig. 1. Experimental bench schematic.
The device allows to measure deformations in the plane orthogonal to the tow axe (fig 1). It has been used to investigate the influences of tow tension and saturation level on the tow transversal behaviour (fig2). Different types of tow, defined by their transversal geometry and filament count, have been analysed. The variability of the tow dimensions among a given type has also been quantified. Various load factors have been applied with and without impregnated tow with different fluids.
Fig. 2. Thickness (a) and width (b) of dry tow, function of compaction for different tension.
The influences of the combinations of the tested variables are quantified using different methods and provide the basis for a set of key parameters for behavioural modelling, to be applied to the simulation of the processes mentioned above.