As the human culture has developed, it has undergone advancements from the Stone Age, through the Iron Age, to the 21st century, in which composite materials are in use. Koyanagi Laboratory mainly deals with high-specific-strength polymeric composite materials for the aerospace field and conducts mechanics-based studies and development of novel functional materials. Thermal and mechanical properties of composite materials and structures are evaluated experimentally and analytically for aircraft and spacecraft designs. We aim to improve material properties through the production of new composites.
The carbon-reinforced polymeric composite (CFRP) is the most familiar composite that is mainly intended for aerospace applications. 50% of the weight of Boeing 787 aircraft corresponds to CFRP. The aircraft is designed such that initial damage of CFRP laminates does not occur. However, the occurrence of initial damage is time and cyclic-load dependent; the damage initiation mechanism is still under investigation. The initial damage is highly dependent on the microscopic damage attributed to the elasto-viscoplastic property of the polymer material. Koyanagi Laboratory performs multiscale digital image correlation (DIC), a method for full-field strain measurement, and multiscale modeling to investigate the occurrence of initial damage..
A spacecraft departing from the Earth has to reduce its kinetic energy when it returns to or reaches its destination planet; otherwise, it may pass over without orbiting the planet or it may collide with the planet. This is because a certain amount of kinetic energy is necessary to leave the gravisphere of the earth. On planets with an atmosphere, thermal energy is generated by friction between the atmosphere and the spacecraft; in other words, kinetic energy is converted into thermal energy and the spacecraft slows down allowing it to arrive safely at its destination. Of course, the spacecraft may also burn up when leaving or reentering the atmosphere, a basic principle in the field of aerospace. Koyanagi Laboratory performs studies on protection from heat generated when spacecraft enter the atmosphere of Mars and Earth. We design the heat shield for re-entering spacecraft, the evaluation of its heat resistance, its thermal analysis, and the evaluation of the insulation material. We perform collaborative investigations with Japan Aerospace Exploration Agency (JAXA), so that the student in charge of this theme in a doctoral or master's thesis will continue to work on such research as a trainee of JAXA.
A study using graphene has been widely spreading from 21th century.. In the Koyanagi laboratory, we develop the new composite material using graphene. It can be conductive high strength composite film development, the semiconductor of the polymeric film and the high efficiency of the use as photocatalyst and the electric catalyst, a lithium-ion battery and the fuel cell, a super condenser put various application such as the use in the field of vision for the use, an ultrathin electrode and the heavy metal ion removal as the use as the solar battery, an application to biotechnology such as the drug delivery, an electrochemistry sensor, an optics sensor and so on. We are trying to develop such kinds of the functional graphene composite material. The final aim is preparing the super high strength graphene composite material, and the target strength is 50GPa. It can be expected the use as the cable of future space elevator when it can meet this strength. We are convinced that the construction of the space elevator brings dramatic acceleration for space advance of human being.