Study On Experimental Device Oriented To The Mechanical Properties Of Long-eared Owl Flight Feathers Barbs

In order to research the mechanism of owl class animal flight with little noise, our group has studied on the mechanical properties of Long-cared owl’s fly plume multistage barbs. In addition to the rachis, the feature sizes of multi-level flight feathers barbs are in micron dimension. So the test of barbs is belonging to the category of microscale mechanical testing. On the basis of summing up the work of predecessors, an off-chip micro tensile test device was designed and built. This tensile testing system droved by a piezoelectric ceramics micro-actuator; the displacement and load cell detect resolution with nanoscale and microscale respectively; and equipped with an image acquisition unit to guide sample installation and monitor testing process by real-time. In this paper, according to the needs of long-eared owl flight feathers barbs testing, design and improvement has performed to the testing system. The main job are following:Software system of the test platform was programmed in LabVIEW graphical programming environment, mainly includes data acquisition unit, image capture unit, video capture, image calibration, image application unit and data processing unit. It can achieve calling non-NI data acquisition card and image acquisition card in LabVIEW by use of VISA and ActiveX controls. Using this software could realize data display, save, processing and real-time monitoring during the experiment when tensile test loaded manually or automatically.Based on the inherent viscoelastic characteristic and big tensile elongation of long-eared owl barbs, the output characteristics of the piezoelectric ceramic micro-driver has been improved:Firstly, because of the piezoelectric ceramic’s output has undesirable characteristics of hysteresis, creep and nonlinear. PID closed-loop control program was used to control it. The piezoelectric ceramic micro-driver realize ideal linear output and of the response speed increased nearly10times compared to open-loop after controlled. It meet the uniform load and fast response requirements of the flight feather barbs tensile test. Besides, according to the piezoelectric ceramic micro-driver’s output is limited, a two-level symmetrical flexible hinge micro-displacement amplification mechanism based on the principle of leverage was designed and simulated. The piezoelectric micro-driver output achieved to230μm after amplified. Due to the irregular morphology of owl flight feathers barbs sample, it is difficult to clamp. To solve this problem a mechanical micro fixture was designed. Then the overall stiffness of the test system was calibration when use this fixture, finally, long-eared owl flight feathers barbs’tensile test was carried out by use of the micro fixture and get it’s Young’s modulus was3.13GPa to3.66GPa. The test system could meet the test requirements of the fiber materials like biological hair by use of this fixture.