Search

This paper describes the role, fundamental classification, and functionality of processing aids. The recent technical trends and future views of processing aids are also described in detail.

The manufacturing processes of the rubber products are complicated, and the importance of processing aids improving the processability is increased. The function of the processing aids, fatty acid derivatives, is mainly based on lubricity. It would be affected by a kind of rubber and/or ingredients. This text explains the function and the usage of the processing aids in the order of the rubber processes. In addition, it introduces new processing aids that bring about other function than lubrication.

Durability and damage tolerance of subcomponent and full-scale wing box structure fabricated by VaRTM are evaluated. Fatigue spectrum with load enhancement factor was applied to the test articles for 1 DSO of 40,000 flights. The Mini-TWIST fatigue spectrum is used for both tests. Then, impact damages are given to the skin stiffened by co-cured stringer and typical skin part by drop-weight to create the delamination. After that, impact damage growth is evaluated during 1 DSO fatigue spectrum and optimal inspection interval is examined. Finally, residual strength of structures is verified by ultimate load test with 150% design limit load. Applied strain level for Subcomponents are intentionally higher than original one in order to evaluate the structural performance in more critical condition. Non-destructive inspection is carried out by 3D ultrasonic scan system with multiple-array sensors to evaluate delamination growth. In Subcomponent test, stringer run-out shows local out-of-plane deformation and that causes disbonding of stringer termination. The disbonding area gradually increases during 1 DSO fatigue test. However, the structure did not show any degradation of structural performance. The damage tolerance tests verify that impact-induced delaminations have not grown throughout the 1 DSO. In the final ultimate load test, the load bearing-capabilities of present VaRTM wing structure have been verified and the structure could survive for 4 seconds without any detrimental deformation and damage growth.

A scanning beam collimation (SBC) method is developed for measuring dynamic angle variations in which an acousto-optic deflector is used as a diffractive scanner to compensate the angle variation in real time, and a position sensor is used to detect the position of the beam that is reflected from the reflector (i.e., object) to be measured. The angle variation can be measured at high speed due to the very high scanning speed available in the acousto-optic deflector. There was good agreement between the angle variation measured using the SBC method and that using a conventional electronic autocollimator. The repeatability, resolution, and linearity of the scanning beam collimation method were determined using a piezo translator to generate tilt angle; the results showing that high accuracy also can be achieved in dynamic angle variation measurement. The SBC method was applied to measure the tilt angle variation caused by the beating force of a dragonfly attached to one end of a gauge block. The results confirmed the effectiveness of this new method.

A new method has been developed to simultaneously measure the thickness and shape of a thin film, such as a dragonfly wing. The innovation in the method is the combining of a heterodyne interferometer and a laser triangulation displacement sensor into one optical system. We confirmed the accuracy of the method by measuring the displacement of a glass plate and the thickness variation generated by a rotated glass plate. The system has a relative accuracy of 1% in the shape measurement and 1.3% in the thickness variation measurement. The method was then applied to a dragonfly wing. The results indicated that the method is very effective in biomechanics studies, such as evaluating the flight performance of dragonflies. In such evaluations, it is essential to measure the high accuracy the variations in both shape and thickness of the wing simultaneously.

A new method for measuring vibrations using a quadrant position sensor has been developed. It allows non-contact measurement of natural frequencies of objects which are small or light and transparent. The natural frequencies in two dimensions can be received at the same time. The system consists of a laser light source, a quadrant position sensor and spectrum analyzer. The object is illuminated by divergence laser rays coming from a microscope objective. The vibration amplitudes are magnified and detected by the position sensor. By adjusting the distance between object and microscope objective or detector, the sensitivity and linearity of the system can be changed. The natural frequencies of a plastic plate were measured by this method. The experimental results agreed well with the calculation results according to the theory of material mechanics. This method is very useful in the research field of millibioflight. The natural frequencies of the dragonfly wing, which is lighter than 0.1 mg, has been measured by this method. We can determine the natural frequencies of bending and torsional deformation by using the information of two dimensions.

The flight mechanism of insects has not yet been understood. Their wings produce more lift than predicted by steady‐ or quasisteady theory. The importance of unsteady aerodynamic mechanisms is now recognized but, except for the specialized ‘‘flying’’ mechanism, the origin of the extra lift is unclear. An attempt is made to explain the unsteady aerodynamic forces by aeroacoustics approach. Sound generated by a moving surface can be physically understood as composition of wing thickness noise, loading noise, and other elements, such as vortex noise. In insect flight, the velocity of the wing tip is much smaller than the velocity of sound, and the compressibility of the air can be neglected. In this case, it becomes easy to calculate the fluttering noise from a given aerodynamic load on the wing surfaces. A new approach to understanding the lift generation mechanism is proposed.

A new method for measuring vibrations using a quadrant position sensor has been developed. It allows noncontact measurement of natural frequencies of objects that are transparent and small or lightweight, such as dragonfly wings. It simultaneously measures natural frequencies in two dimensions without any reflective mark having to be placed on the object. The system consists of a laser light source, a quadrant position sensor, and a spectrum analyzer. The object is illuminated by divergent laser rays coming from a microscope objective lens. The vibration amplitudes of the object are magnified and detected by the position sensor. By adjusting the distance between the object and either the lens or the sensor, the sensitivity and linearity of the system can be changed to measure objects of different size. We measured the natural frequencies of a dragonfly wing along the chord and the span, using a vein as a mark to measure displacement during vibration. This allowed us to determine the natural frequencies of bending and torsional deformation. Our results show that this two-dimensional, noncontact method can be effectively applied to the field of millibioflight.