Modelling negative linear compressibility in tetragonal beam structures

Most materials compress axially in all directions when loaded hydrostatically. Contrary to this, some materials have been discovered that exhibit negative linear compressibility and, as such, expand along a specific axis or plane. This paper analyses a fundamental mechanism by using a combination of finite element simulations and analytical derivations to show that negative linear compressibility can be found in a body-centred or face-centred tetragonal network of nodes connected by a network of beams. The magnitude and direction of this behaviour depends on the cross geometry in the network.

► Most materials compress axially in all directions when loaded hydrostatically. ► We investigate the possibility of negative linear compressibility in beam structures. ► Structures are 2D rectangular and 3D tetragonal, with various beam geometry. ► We use both analytical model and finite element analysis. ► Diagonal beams generate NLC, which is maximum at aspect ratio close to two.