The variant aircraft can flexibly change its shape to achieve the best sports performance under different flight environments and flight missions. Changing the shape of the wings is a major form of variant aircraft. In this paper, the kingfisher was selected as the bionic object to design a morphing wing. A three-stage lateral folding morphing wing based on Sarrus linkages was presented and applied to the construction of an underwater–aerial transmedia aircraft. The multi-body dynamics method was used to analyze the kinematic characteristics of the morphing wing and to optimize the design of the folding mechanism for the torque values of the hinges between the bottom links. The results showed that the optimized hinge torque value was reduced to 1.2085 N·m, and the lengths of the bottom two links were calculated to be 140 mm and 142 mm, respectively, based on the optimized results. Finally, a series of wing folding and unfolding motion experiments were conducted to prove that the mechanism enabled the span change smoothly, which verified the rationality of the design of this paper.

A direct ventricular assist device is one of the effective means to treat patients with heart failure; the key point of the problem is the flexible sensor that can measure the drive pressure and shape variable of the heart auxiliary device. This study was based on the high-voltage electric field guidance process and the porous foaming process, and designed an implantable resistance/capacitive composite flexible sensor that can effectively detect the pressure and deformation signal caused by fine surface contact and pneumatic muscle expansion. Experiments showed the performance of composite sensors with special structure design was greatly improved compared with the control group—the strain measurement sensitivity was 22, pressure measurement sensitivity was up to 0.19 Kpa⁻¹. Stable strain measurements were made up to 35 times and pressure measurements over 100 times. In addition, we solved the interference problem of resistance/capacitance flexible sensors through an optimized common substrate process. Finally, we tested a pneumatic muscle direct ventricular assist device with a composite flexible sensor on a model heart; the experiment showed that this resistance/capacitive composite flexible sensor can effectively detect surface contact with pneumatic muscle and the displacement signals.

This paper presents a novel design for a bearingless axial flow blood pump based on the magnetic-hydrodynamic double levitated concept. In the axial direction, the magnetic levitation system consisted of two pairs of permanent magnet rings offsets the force of fluid. The hydrodynamic shell mounted on the impeller rotor is designed for generating dynamic pressure, which can balance the radial force like gravity when the blood pump is working. Because of the unsteady force and torque acting on the rotor and the passive suspension, the position of the rotor is not steady. The suspension force, stiffness, and torque of the rotor are calculated by the theoretical method and finite element method. Then, the dynamics of the rotor are analyzed. Arrangements of Hall-effect sensors with the corresponding data acquisition system which can measure the axial displacement of the rotor are explained. The sensorless drive control system for the blood pump is described too. With a prototype pump, an external circulation experiment system is built and then the axial and radial displacements of the rotor are measured by using Hall-effect sensors and the laser vibrometer under different working conditions.

Aiming at insufficient suspension force on the impeller when the hydraulic suspension axial flow blood pump is start at low speed, the impeller suspension stability is poor, and can’t quickly enter the suspended working state. By establishing the mathematical model of the suspension force on the impeller, then the influence of the circumferential groove depth of the impeller on the suspension force is analyzed, and the annular groove depth on the impeller blade in the direction of fluid inlet and outlet was determined as (0.26, 0.02 mm). When the blood pump starts, there is an eccentricity between the impeller and the pump tube, the relationship between the suspension force and the speed of the impeller under different eccentricities is analyzed. Combined with the prototype experiment, the circumferential annular grooving design of the impeller can make the blood pump rotate at about 3500 rpm into the suspension state, when the impeller is at 8000 rpm, the impeller can basically achieve stable suspension at the eccentricity of 0.1 mm in the gravity direction, indicating that the reasonable circumferential annular grooving design of the impeller can effectively improve the suspension hydraulic force of the impeller and improve the stability of the hydraulic suspension axial flow blood pump.

Background: The hydrodynamic suspension structure design of the axial blood pump impeller can avoid the problems associated with using mechanical bearings. However, the particular impeller structure will impact the hydraulic performance and hemolysis of the blood pump. Method: This article combines computational fluid dynamics (CFD) with the Lagrange particle tracking method, aiming to improve the blood pump’s hydraulic and hemolysis performance. It analyzes the flow characteristics and hemolysis performance inside the pump. It optimizes the taper of the impeller hub, the number of blades, and the inclination angle of the circumferential groove at the top of the blade. Results: Under certain rotational speed conditions, an increase in the taper of the impeller hub or the number of blades can increase the pumping pressure of a blood pump, but an increase in the number of blades will reduce the flow rate. The design of circumferential grooves at the top of the blade can increase the pumping pressure to a certain extent, with little impact on the hemolysis performance. The impeller structure is optimized based on the estimated hemolysis of each impeller model blood pump. It could be seen that when the pump blood pressure and flow rate were reached, the optimized impeller speed was reduced by 11.4%, and the estimated hemolysis value was reduced by 10.5%. Conclusion: In this paper, the rotor impeller structure of the blood pump was optimized to improve the hydraulic and hemolytic performance effectively, which can provide a reference for the related research of the axial flow blood pump using hydraulic suspension.

With the development of various new intelligent materials, pneumatic artificial muscles are becoming widely used as actuators in industry, with their advantages of having a simple and compact structure, smooth action, fast response and movement closer to natural biological muscle movement. This paper introduced the concept of a fiber-constrained flexible actuator for direct ventricular assist devices. The structural parameters of the actuator were initially determined based on the morphology of the human heart; the model of the flexible body with fibers and strain limiting layer was then constructed using SOLIDWORKS; then, the model was imported into the ABAQUS finite element analysis software for simulation in order to determine the feasibility of the structural solution; finally, the structural parameters of the actuator were optimized based on the simulation results. In order to investigate whether the actuator could cause damage to myocardial tissue when squeezing the heart, the actuator was tested for the displacement and the output force. The results showed that fiber-constrained direct ventricular assist devices did not damage the myocardium while assisting the heart to pump blood; moreover, their blood output could meet the requirements of both types of heart failure patients. The annular flexible actuator can provide effective compression of the ventricle and twist at an angle during inflation. This twist adapts to the torsional requirements of the heart, and reduces sliding friction between the device and the heart surface, thereby reducing myocardial damage.