Mechanical Analysis of Shape Memory Alloy Beams under Asymmetric Bending

Based on the bending theory of beams, combining with the constitutive relationship of shape memory alloy materials, the asymmetric bending of shape memory alloy beams under concentrated load was studied. Considering tension-compression asymmetry on both sides of the tension and compression in the process of bending, tension-compression asymmetry coefficient was introduced, by using the step-by-step method. The stress distribution, neutral axis displacement, curvature and phase boundary of the beam sections of the I-shaped cross-section shape memory alloy beam were analyzed. The results show that under the same load, the maximum offset of the neutral axis displacement increases with the increase of tension-compression asymmetry coefficient. Under the same tension-compression asymmetry coefficient, the displacement and curvature of the neutral axis increased with the increase of load; as tension-compression asymmetry coefficient increased, the proportion of mixed phase increased gradually, the proportion of martensite phase decreased, and the asymmetry of phase boundary became more obvious. Under the same conditions, the rectangular section is more suitable. The cross section of I shaped cross section was prone to occur phase transformation.

Programmable deformation of patterned bimorph actuator swarm

Graphene-based actuators featuring fast and reversible deformation under various external stimuli are promising for soft robotics. However, these bimorph actuators are incapable of complex and programmable 3D deformation, which limits their practical application. Here, inspired from the collective coupling and coordination of living cells, we fabricated a moisture-responsive graphene actuator swarm that has programmable shape-changing capability by programming the SU-8 patterns underneath. To get better control over the deformation, we fabricated SU-8 micropattern arrays with specific geometries and orientations on a continuous graphene oxide film, forming a swarm of bimorph actuators. In this way, predictable and complex deformations, including bending, twisting, coiling, asymmetric bending, 3D folding, and combinations of these, have been achieved due to the collective coupling and coordination of the actuator swarm. This work proposes a new way to program the deformation of bilayer actuators, expanding the capabilities of existing bimorph actuators for applications in various smart devices.

FEM Analysis for Asymmetric Bending Roll of Roll Process in Four-High Mill

Accurate prediction for the deformation of the roll system is a key to improve the accuracy of the preset model and on-line control model of strip cold rolling processes. A non-linear finite element contact model to simulate the roll system deformation has been developed for4h cold strip rolling mill. Roll process of 4-high cold strip mill is simulated and analyzed by 3D elastic-plastic FEM on the bases of software ANSYS. In the model, the elastic deformation of work roll and backup roll, the plastic deformation of the strip and the pressure of strip and the work and the backup roll were taken into account. Results show that the work roll HYPERLINK "javascript:showjdsw ('showjd_0','j_0')" asymmetric bending is the most effective mean in these strip shape controlling means. The calculated roll gap profile is close to the measured values. This model can improve the accuracy of final products through a correct preset model and on-line control model of strip.

Structural Efficiency Measures for Sections Under Asymmetric Bending

Shape factors evaluate the efficiency of material usage in a structure. Previously, they have been developed for simple bending but, in practice, beams often have a more complicated bending response. Therefore, shape factors that account for asymmetric bending are introduced. The shape factors are applied to six example beam sections to demonstrate the effect of shape and load on structural efficiency. The shape factors are also enhanced for inclusion in a more general measure of structural efficiency, the performance index, comprising elements of both geometry and material. Next, a study is performed to show how the asymmetry of a beam section affects structural efficiency. The shape factors can quantitatively evaluate the structural efficiency of beam sections, demonstrating the effect of asymmetric bending on the structural response. Therefore, these shape factors can be used for concept selection and to provide insight into optimal structural design.