Considering the fibre-orientation of reinforced polymers in structural simulations

Significance 

Desirable attributes, such as: corrosion resistance, high specific strength and geometrical freedom make injection moulded glass fibre reinforced plastics popular among designers. These outstanding properties help minimize the environmental impact, cost and weight of load bearing components. The primary drawback they suffer is that they tend to show both non-linear and strong anisotropic material behaviour, which render their in-use behaviour unpredictable. Injection moulding simulations are able to provide second order orientation tensors which describe the local fibre orientation, however they are not commonly combined with structural simulations. In addition, due to the complex mechanisms behind the mechanical behaviour of fibre reinforced polymers, material parameters governing plasticity and damage need to be determined by optimizing the simulation response towards experimental stress-strain curves for known geometries and fibre orientations.

Recently, Jönköping University researchers in Sweden: Johan Jansson (PhD candidate), Engineer Tim Gustafsson, Dr. Kent Salomonsson, Dr. Jakob Olofsson, Dr. Joel Johansson in collaboration with Engineer Peter Appelsved at Kongsberg Automotive and Mikeal Palm at Husqvarna Group developed a new method that would enable accurate prediction of the anisotropic and non-linear behaviour of glass fibre reinforced plastics using finite element methods. They developed and implemented a material model so as to remedy the need of multiple material definitions, and to control the local plastic behaviour as a function of the fibre orientation. Their work is currently published in the research journal, Composite Structures.

In brief, the research method employed entailed giving analytically the elastic behaviour of each element, by an orientation averaged and extended Mori-Tanaka homogenization scheme, applicable to materials of higher fibre volume fractions by considering the fibre-fibre interactions. Additionally, the researchers described the plastic behaviour phenomenologically by a hardening functional, given in terms of hardening polynomials which were defined by experimental stress-strain data and parameter optimization using simulations. All in all, fourth order tensors were used in combination with traditional methods to provide more accurate material properties.

The authors observed that it was possible to capture the stress-strain behaviour of the tensile tests with good accuracy by optimizing the material model. More so, they noted that the developed calibration process resulted in material specific hardening polynomials, which could be used to model other geometries using the same material. The elastic and plastic material behaviour were also seen to vary locally as a function of the fibre orientation.

In summary, Swedish scientists successfully presented a methodology that uses different material properties in every material point with one material definition. They emphasize that by using more advanced material models, potential weight reductions in industrial components is made possible. Altogether, the presented material model can support design engineers in making more informed decisions, allowing them to create smarter products without the need of excessive safety factors, leading to reduced component weight and environmental impact.

“By developing tools which make it easier for design engineers to consider the influence of the manufacturing process in subsequent structural simulations, we hope to increase the potential for weight reduction and performance optimization in industrially manufactured components. The general methodology does not only apply to injection moulded components, but really to any process which yields local property variations in the manufactured component, such as casting, forging, etc.” Said Johan Jansson in a statement to Advances in Engineering.

Considering the fibre-orientation of reinforced polymers in structural simulations - Advances in Engineering Considering the fibre-orientation of reinforced polymers in structural simulations - Advances in Engineering

About the author

Johan Jansson is a PhD student at the department of Materials and Manufacturing at Jönköping University, Jönköping, Sweden within the Simulation Technology research group. He has a Bachelor of Science in Mechanical Engineering from 2014, and a Master of Science in Product Development and Materials Engineering from 2016. Prior to joining Jönköping University as a graduate student, he worked as an R&D Engineer at Saab Avionics Systems, Jönköping, Sweden.

His research interests include material modelling in various forms such as constitutive modelling, multiscale modelling and homogenization methods.

About the author

Tim Gustafsson is an Engineer working at Volvo Cars Body Components in Olofström, Sweden. He has a Bachelor of Science in Mechanical Engineering from Linnaeus University 2014, and a Master of Science in Product Development and Materials Engineering from Jönköping University 2016.

About the author

Dr. Kent Salomonsson is an Associate Professor in Computational Mechanics at the Department of Materials and Manufacturing at the School of Engineering, Jönköping University, Jönköping, Sweden. He received his Master of Engineering Physics and PhD in Applied Mechanics from Chalmers University of Technology, Gothenburg, Sweden. He was then postdoctoral research fellow at University of Michigan, Ann Arbor, MI, USA, at the Department of Mechanical Engineering and the Department of Aerospace and Space Engineering. Prior to joining Jönköping University, he has worked at the University of Skövde, Skövde, Sweden, doing research on structural adhesives for the automotive and airplane industry. He has also worked at R&D departments in industry mainly as Lead Analysis Engineer.

His research interest includes biomechanics, characterization of advanced materials, tribology, solid mechanics, multiscale mechanics and computational mechanics.

About the author

Jakob Olofsson received a Master of Science degree at Linköping University in January 2005. The studies were within Mechanical Engineering with specialisations in Solid Mechanics and Materials Science. He then worked for five years in the industry, first as mechanical design engineer and design responsible of power turbine parts for gas turbines, and then as design engineer and CAE engineer within the automotive industry. In September 2009 he started his Ph.D. studies at the department of Mechanical Engineering and the research environment Materials and Manufacturing — Casting at the School of Engineering, Jönköping University. In 2012 he presented his licentiate thesis, and in 2014 he successfully defended his PhD-thesis entitled “Simulation of Microstructure-based Mechanical behaviour of Cast Components”. Since June 2014 he serves as an acting assistant professor at Jönköping University.

About the author

Joel Johansson holds a Doctor of Philosophy in Product and Process Development from Chalmers University of Technology, and a Master of Science in Mechanical Engineering with a focus on Product Development and Design from School of Engineering, Jönköping University and got a position as Associate Professor in Product Development 2018.

His research has considered the flexibility of design automation systems, knowledge based containing conflicting rules, the automation of the finite element analysis process as well as complexity management in design automation.

About the author

Peter Appelsved is a Design Engineer at Kongsberg Automotive working with gear shifter system for the automotive industry. Field of expertise is structural analysis and injection molding analysis. He has a Masters degree in solid mechanics from KTH, Royal Institute of Technology (Stockholm, Sweden).

About the author

Mikeal Palm is a structural analysis specialist working for Husqvarna Group. He has a Master of Science degree from Chalmers University and has previously worked with crash simulations in the automotive industry. His current role at Husqvarna consists of developing methods for different kinds of impact and drop simulations. Other fields of expertise include simulation of production processes such as injection moulding and cold forming of metals.

Reference

J. Jansson, T. Gustafsson, K. Salomonsson, J. Olofsson, J. Johansson, P. Appelsved, M. Palm. An anisotropic non-linear material model for glass fibre reinforced plastics. Composite Structures, volume 195 (2018) page 93–98.

Go To Composite Structures

Check Also

Aging resistant TiO2/silicone rubber composites - Advances in Engineering

Aging resistant TiO2/silicone rubber composites