High Strain Composite (HSC) Structures are a type of composite material that are specifically designed to perform well in a setting in which they will experience a high deformation, or strain.
High Strain Composite (HSC) Structures are a type of composite material that are specifically designed to perform well in a setting in which they will experience a high deformation, or strain. When external forces are applied to the material, the composite will change from one shape to another to accommodate the deformation. Usually HSCs are formed form fiber-reinforced polymers because they are anisotropic and can be uniquely tailored with unique effects upon deformation for a specific application.
Bi-Stable Composite Structures
An important classification of HSC Structures is a group of structures with multiple stable states, known as bi-stable structures. These types of structures can be something as innocuous as a spring-loaded pen or something as complex as a part on a spacecraft. A system with bistability has two stable equilibrium states. For example, a light switch is a bi-stable system. It is designed to rest in either the “on” or “off” position, but not in any position between the two. In mechanical systems, bistability is described as the ability of a material to be present in two stable phases that both exist within a given temperature range. This is commonly described as “over center,” meaning that work is done on the system to move it just past the peak between stable states, at which point the system will bring itself to equilibrium at the second state.
High Strain Composite Structures Applications
Most commonly, HSC structures are used in applications where low weight, low volume materials are desired. For example, within the aerospace industry, flexible composites are used for deployable mechanisms like antennas or solar arrays. For several decades, metals commonly used in springs (high strength steel, aluminum, and beryllium copper alloys) have been used in such deformable aerospace structures. They are still used today in many of these applications, particularly those where the highest compaction ratios and electrical conductivity are required. However, metals have higher densities, higher coefficients of thermal expansion, and lower strain capacities than composite materials can provide. Therefore, recently, as the need for high performance deployable structures has increased, the use of HSC Structures has increased significantly.
In the future, with the continuing increase in complexity of aerospace applications, it is conceivable that the use of high strain composites will increase as well. As the use of high strain composites increases, it is likely that we will see an increase in research on the subject and an advancement in the properties that high strain composites can provide.