This contribution deals with the nonlinear analysis of shape memory alloy (SMA) adaptive trusses employing the finite element method. Geometrical nonlinearities are incorporated into the formulation together with a constitutive model that describes different thermomechanical behaviors of SMA. It has four macroscopic phases (three variants of martensite and an austenitic phase), and considers different material properties for austenitic and martensitic phases together with thermal expansion. An iterative numerical procedure based on the operator split technique is proposed in order to deal with the nonlinearities in the constitutive formulation. This procedure is introduced into ABAQUS as a user material routine. Numerical simulations are carried out illustrating the ability of the developed model to capture the general behavior of shape memory bars. After that, it is analyzed the behavior of some adaptive trusses built with SMA actuators subjected to different thermomechanical loadings.

The dynamic collapse of submerged cylindrical shells subjected to lateral impulsive pressure loads caused by underwater explosions is studied via coupled experimental and numerical work. Two sets of experiments were performed. Initially, 50.8 mm outside diameter aluminum tubes with diameter-to-thickness ratio of 32.3 were tested inside a pressure vessel. Hydrostatic pressure was applied quasi-statically up to the onset of collapse in order to obtain the collapse pressure of the tubes tested. Subsequently, similar tubes were tested in a 5 m × 5 m × 1.6 m deep water tank under various explosive charges placed at different distances. Explosive charges and standoff distances were combined so as to eventually cause collapse of the specimens. Dynamic pressures were recorded using a fit-for-purpose data acquisition system with sampling rates of up to 1 mega samples/s/channel. In parallel, finite element models were developed using commercially available software to simulate underwater explosion, pressure wave propagation, its interaction with a cylindrical shell, and the subsequent onset of dynamic collapse. The surrounding fluid was modeled as an acoustic medium, the shells as J2 flow theory based materials with isotropic hardening, and proper fluid–structure interaction elements accounting for relatively small displacements of the boundary between fluid and structure were used. Subsequently, the physical explosion experiments were numerically reproduced with good correlation between results. Finally, a parametric study was carried out to examine the effect on the pipe under different impulsive pressure loads.

The use of shape memory alloys (SMA) in smart sensors and actuators is already well established in many areas such as biomedical and aerospace engineering. Likewise, SMA’s have an enormous potential for offshore oil and gas applications. They can be used, for example, in active vibration control devices or in deep water valves as actuators. In this work, two different prototypes of SMA actuation valves are developed — a linear and rotate sliding sleeve. Several tests were performed to determine the maximum force, maximum displacement of the devices. In parallel, numerical simulations using constitutive model of shape memory alloy are carried out to capture the behaviour of SMA actuators under different thermo-mechanical loadings.