![Table 1 Adopted material parameters for simulation of the NiTi actuator [1].](/figures/table-1-adopted-material-parameters-for-simulation-of-the-2122c6wt.webp)
Q2. What is the effect of the thickness of the actuator on the stroke?
It should be remarked that, when the membrane thickness increases, stiffness increases inducing a higher stress, the maximum transformation strain becomes significant, and consequently the deflection of the actuator is increased.
Q3. What is the effect of increasing the spacer length?
The increase of the spacer length induces a high stress leading to a high martensite self-accommodation and low martensite orientation in the membrane.
Q4. What are the constitutive equations of this model?
The constitutive equations of this model were derived from an assumed expressions of the Gibbs free-energy and the dissipation function.
Q5. What is the method for heating the SMA membranes?
In the present work, the heating of SMA membranes was obtained by applying an electrical current, and the electrical resistivity of the SMA thin film is suitable for Joule heating.
Q6. What are the three parameters that were considered in the study?
For geometrical parameters, thermal loading and the martensite orientation start yield stress, three different values were considered in order to carry out their influence on the actuator behavior.
Q7. What is the purpose of the parametric analysis?
The parametric analysis allowed on the one hand, to study the thermomechanical behavior of the NiTi actuators, on the other hand to define an optimal design able to provide a large stroke for a minimal size actuator geometry.
Q8. What is the explanation for the low frequency of the NiTi actuator?
It is well known that the SMA actuator is able to provide high stroke with low frequency due to the slow response time during the air-cooling of the NiTi membrane.
Q9. What is the criterion for a really predictive model?
To tend towards a really predictive model, a huge experimental work is necessary in order to improve the identification of all the physical parameters introduced in the model.
Q10. What are the possible actuation methods for the SMA actuator?
There are several possible actuation methods for such SMA actuator:(1) Heating and cooling of the SMA membranes [47]: there are two types to heat up SMA.
Q11. What can be done to improve the performance of the actuator?
the developed model can be broadened by adding of diverse physics, such as the interactions between the fluid/structure and microvalve effect in order to assess durability and long-term performance of actuator.
Q12. Why is the diameter of the actuator difficult to measure?
due to difficulties in fabrication of such actuator with a spacer between two NiTi membranes, a diameter of 0.5 mm corresponds to a good compromise.
Q13. What are the driving forces of the FE model?
The driving forces corresponding to internal and control variables were derived and compared to the corresponding yield forces in order to determine active mechanisms.