Tailie Jin

Use of a digital image correlation technique for measuring the material properties of beetle wing

Beetle wings are very specialized flight organs consisting of the veins and membranes. Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally. In the present study, we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane. Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm). We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane. The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator. We used an ARAMIS™ system based on the digital image correlation technique to measure the corresponding displacement of a specimen. The thickness of the beetle wing varied at different points of the membrane. The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy; the elastic modulus in the chordwise direction is approximately 2.65 GPa, which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa. As a result, the digital image correlation-based ARAMIS system was successfully used to measure the elastic modulus of a beetle wing. In addition to membrane’s elastic modulus, we considered the Poisson’s ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine. The result reveals the Poisson’s ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.

Anisotropy and non-homogeneity of an Allomyrina Dichotoma beetle hind wing membrane

Biomimetics is one of the most important paradigms as researchers seek to invent better engineering designs over human history. However, the observation of insect flight is a relatively recent work. Several researchers have tried to address the aerodynamic performance of flapping creatures and other natural properties of insects, although there are still many unsolved questions. In this study, we try to answer the questions related to the mechanical properties of a beetles hind wing, which consists of a stiff vein structure and a flexible membrane. The membrane of a beetles hind wing is small and flexible to the point that conventional methods cannot adequately quantify the material properties. The digital image correlation method, a non-contact displacement measurement method, is used along with a specially designed mini-tensile testing system. To reduce the end effects, we developed an experimental method that can deal with specimens with as high an aspect ratio as possible. Youngs modulus varies over the area in the wing and ranges from 2.97 to 4.5 GPa in the chordwise direction and from 1.63 to 2.24 GPa in the spanwise direction. Furthermore, Poissons ratio in the chordwise direction is 0.63-0.73 and approximately twice as large as that in the spanwise direction (0.33-0.39). From these results, we can conclude that the membrane of a beetles hind wing is an anisotropic and non-homogeneous material. Our results will provide a better understanding of the flapping mechanism through the formulation of a fluid-structure interaction analysis or aero-elasticity analysis and meritorious data for biomaterial properties database as well as a creative design concept for a micro aerial flapper that mimics an insect.

Finite Element Modeling of a Beetle Wing

Numerical simulation is a very important method for understanding the behaviors of insect flight. In this study, a method of building a finite element model is proposed on the basis of a real beetle wing, which is 50 mm long in the spanwise direction and 20 mm long in the chordwise direction. We scanned a real beetle wing using a scanner to get the 2D image. The scanned 2D image was used to produce CAD data of the outer lines of the membranes and veins. Then the lines were used to build the finite element model. The model was divided into 48 regions so that the variation in the thickness of the membranes and veins could be taken into account. The effect of the cross section of the veins on the exactness of the finite element model was investigated. The finite element model was used to simulate the bending test of a real beetle wing, and the analysis results are in agreement with the experimental results.

Performance of piezo-stacks for a piezoelectric hybrid actuator by experiments

Piezoelectric-hydraulic actuator is a hybrid device that consists of a hydraulic pump driven by piezoelectric stacks coupled with a conventional hydraulic cylinder and a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, operation principle and performance testing of the hybrid actuator were introduced. Two types of piezo-stacks are selected for experimental performance testing to identify the factors of piezo-stack which affect the performance of the hybrid actuator. The performance of piezo-stacks due to electrical power supply and self-heating was considered. Output no-load velocities and blocked force were measured on performance testing. The results showed that the maximum blocked force was 346 N and no-load velocity was 101 mm/s, resulting in maximum output power of 8.74 W at 1000 V applied voltage and 250 Hz pumping frequency.

Dynamic Characteristic of an Artificial Wing Mimicking a Beetle Hind Wing

Biomimetics is one of the most important paradigms as researchers seek to invent better engineering designs over human history. However, the observation of insect flight is a relatively recent work. Several researchers have tried to address the aerodynamic performance of flapping creatures and other natural properties of insects, although there are still many unsolved questions. In this study, we have attempted to investigate the structural dynamic characteristic of an artificial wing that mimicked the wing shape and main venation structure of a beetle hind wing using a non contact measurement method. The structural dynamic characteristic of the artificial wing was measured and compared to the real beetle hind wing by determining the natural frequencies and damping factor. The artificial wing was glued with the cyanoacrylate adhesive at the wing base onto the acrylic stand which was attached to the base of a shaker. The shaker produces the translation motion in the lateral direction of the wing plane. A non-contact laser sensor was used to measure the displacement history of the painted spots on the hind wing. A Bruel & Kjaer FFT analyzer was adopted to calculate the frequency response functions where the natural frequencies of the wing structure can be extracted. The fundamental natural frequency of artificial wing is 51.3 Hz while the natural frequency of the beetle hind wing is 48.8 Hz. In addition, the wing structures were lightly damped with damping factor around 3.1% that is close to the one of beetle hind wing. We found that, in terms of the wing elasticity, the plastic wing frame of artificial wing was suitable for beetle-like flight.Copyright

Performance Testing of an Integrated Hybrid Actuator

The piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, operation principle and performance testing of the hybrid actuator were introduced. Output velocities have been measured in both loaded case and not loaded case and the blocking force also has been measured in external loaded case. The maximum velocity of the actuator is 53.3 mm/s, blocking force is 240.7 N and corresponding power output is 3.2 W.

Thermal strain measurement of a double ring structure using digital image correlation method

Thermal output is a source of large error in the thermal deformation measurement of specimens under temperature change when a strain gauge is used. In this study, the digital image correlation (DIC) method is employed to measure the full-field thermal deformation and strain of a double ring structure consisting of an inner aluminum ring and an outer titanium ring. The thermal deformation of the ring was measured up to 200 degrees C and the heating condition of the double ring structure was analyzed by finite element simulation. The results confirm that the deformation and strain fields obtained from the DIC method were in good agreement with the analysis result.

Measurement of Thermal Deformation of a Double Ring Structure using Digital Image Correlation Technique

In this paper, thermal deformation of a double ring structure using digital image correlation technique (DIC) was measured. The double ring structure consisted of two parts; the inner ring was aluminium which had a large thermal expansion coefficient and the outer ring was titanium which had a small thermal expansion coefficient. We heated the double ring structure from to in a chamber and at the same time, two cameras captured surface images of the double ring structure. Initially, there was a 21 gap between the inner ring and outer ring. The gap was closed at around and after that, two rings expanded together. In order to compare the experimental results with analysis results, a finite element analysis was performed using ANSYS. The results of DIC measurement and ANSYS analysis were compared and agreed well.

THERMAL STRAIN MEASUREMENT OF A DOUBLE RING STRUCTURE USING DIGITAL IMAGE CORRELATION METHOD

Thermal output is a large error source in the thermal deformation measurement of specimens under temperature change when a strain gage is used. Although several methods have been developed and used to compensate thermal output, the range of measuring temperature is limited to several hundred degrees C. In this study, we used a digital image correlation (DIC) method to measure the full-field thermal deformation and strain of a double ring structure consisting of an inner aluminum ring and an outer titanium ring. Thermal deformation of the ring was measured up to 200 degrees C, and a finite element simulation for the heating condition of the double ring structure was performed. The deformation and strain results from the DIC method and simulation were in good agreement.

Material property measurement of bio-structures using digital image correlation technique

In the present study, a digital image correlation method has been applied to measure the elastic modulus of a beetle wing membrane. Specimens were prepared by cutting beetle wing carefully with a size of 3.0 mm in width and 5.0 mm in length. We used a scanning electron microscope for exactly measuring the membrane thickness of a beetle wing membrane. The specimen was attached to a designed fixture to induce a uniform displacement using a micromanipulator. We measured the applied load and the corresponding displacement by a load cell with a maximum capacity of 5 N and by an ARAMIS system based on the digital image correlation method respectively. The measured thickness of a beetle wing varied from point to point of the wing part and the elastic modulus was different according to the loading direction. In conclusion, we successfully measured the elastic modulus of a beetle wing with an ARAMIS system based on the digital image correlation method.