We interviewed PhD student Karl Arvidsson about his work as part of sub-project 9 entitled “Multifunctional optimisation for electrically insulating composites”. The project aims to develop an experimental methodology for evaluating new combinations of composite materials on a laboratory scale, taking into account both mechanical and electrical properties.

What experimental methods do you think you will work with to evaluate the mechanical and electrical properties of composite materials? 
Initially, we will focus on the electrical properties of composites as these are not as well-studied as the mechanical properties. Our group has purchased a new testing machine that can test the dielectric strength of various materials, that is, the voltage a material can withstand before electrical breakdown occurs and it becomes conductive.

Can you give examples of new material combinations you plan to evaluate? 

Today, glass fiber-epoxy composites are a common material in high-voltage insulators. We will use this as our reference material to gain an understanding of what affects the properties of insulators. Based on these results, we hope it will then be easier to evaluate other types of materials, such as different types of biocomposites.

Why is this work important from a green transition perspective? 

With the green transition and the electrification wave we are now seeing, the need for high-voltage components such as insulators has increased significantly. It is therefore very important that there is a sufficient supply of these types of products so that the transition is not slowed down, but also that the products are developed and become more sustainable in themselves. A deep understanding of the critical mechanisms for composite insulators is a prerequisite for being able to reduce material usage and to be able to use new, more sustainable materials.

What are the biggest challenges you foresee when it comes to optimizing electrically insulating composites for stable power transmission? 

Since not much research has been done on composite materials in insulators, there is no clear consensus on how electrical and mechanical strength interact. There are extensive theories and testing methods for mechanical properties but considerably fewer studies on insulation ability. We will therefore need to develop robust testing methods for electrical strength that give us reliable results and where we understand what happens in these materials.

How do you plan to handle the balance between improving both the mechanical and electrical properties of the composite materials? 

Unfortunately, there are certain parameters where improved mechanical properties mean worsened electrical properties (for example, the direction of the fibers in the composite). In these cases, we hope to be able to show how and to what extent these parameters affect the properties, which we believe can contribute to a more optimized design overall. But we also hope to be able to change the material so that both the electrical and mechanical properties are improved simultaneously.

Do you have any companies attached to this subproject? 

Hitachi Energy Composites in Öjebyn, which manufactures high-voltage insulators from composite materials, is involved in the project. They have shared test materials that we have been able to use in the startup and testing of our new testing machine. But above all, we have been able to share experiences and bounce ideas as they have extensive experience with composite insulators. It feels very good to have Hitachi in the project and thus get inputs from the industry and their challenges.