Mechanism and experiments of asymmetrical pitch system for MAV
In view of problem for miniaturizing Micro Air Vehicles (MAV), a novel asymmetrical pitch system faced to rotary wing MAV is introduced. The pitch mechanism and control characteristics are studied and analyzed. Because the deformation of elasticity link is key to generate the blade pitch, it is analyzed and calculated by elasticity finite element method. And the results illustrate the linear relationship between blade pitch angles and the output torque of the motor. Based on control system of asymmetrical pitch, mechanism experiments based on strain gauge are done, and the factors that affect the deformation of the elastic linkage is analyzed. Results indicate that mechanism of asymmetrical pitch is effective.
A Novel Asymmetrical Pitch System and Elasticity Mechanics Analysis
A novel asymmertrical pitch system faced to rotary wing MAV is introduced.The pitch mechanism and control characteristics are studied and analyzed.Because the deformation of elasticity link is key to generate the blade pitch,it is analyzed and caculated by elasticity finite element method.And the results illustrate the linear relationship between blade pitch angles and the output torque of the motor.The phase of rotary wing can be measured by the photoelectric encoder.So the flight to all directions can be carried out when the motor is accelerated at expectant phase.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.