著者

滝田 好宏 樫谷 賢士

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.431, 2016 (Released:2017-06-19)

---

This paper investigates a VTOL UAV with tailless wing configuration. In the previous our work for multi-rotor UAV, a trirotor geometry with four rotors was built and experimented flight in the laboratory. VTOL type UAV enables the flight without take-off and landing spaces. So, there many researches for VTOL type UAVs, but the effective configuration of wing and electric propulsion unit is not discovered. This paper proposes a tailless wing configuration combined with the trirotor geometry for VTOL UAV. The Tailless wing airplane has advantage of low friction force, simple structure and lighter than the normal airplane with same wing area. The disadvantage of tailless wing type is that low stability in pitch and yaw motions. In order to overcome these problems, a stable airfoil with low moment coefficient is used and designed the configuration the wing. The experimental model of tailless wing for VTOL UAV is built and experimented flight in the field. Experimental results show the maneuver of designed tailless wing UAV.

著者

岡村 宏 大石 久己 土屋 賢康 長谷川 浩志

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.339, 2016 (Released:2017-06-19)

---

We report the result of test that has given the acoustic excitation to the new guitar in the aging cell with using the Bach's cello suites. The sound quality effect of playing the guitar for five years is the same as one of the four weeks aging test with the high load. However, the too much aging gives the new guitar the adverse effects. In this time, we were able to have the good balance results with the light load aging. But there were few effects in the upper position sounds of the guitar. The sound range of the cello is not enough to the acoustic excitation of high frequency zone. So, we will try soon the aging test with playing the violin pieces.

著者

北林 研人 石原 匡 鞍谷 文保 吉田 達哉 小出 俊雄 水田 泰次 長村 光造

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.340, 2016 (Released:2017-06-19)

---

Cymbals are thin domed plates used as percussion instruments. When cymbals are stuck, they vibrate and radiate sound. Cymbals are made through spin forming, hammering, and lathing. The sound radiated from a cymbal depends on its vibration characteristics that are determined by the shape and dimension. The hammering produces plastic deformation on the cymbal's surface, generating residual stresses throughout it. Although the vibration characteristics are changed by the hammering to adjust cymbal sound, the effect of the hammering on the cymbal sound is not clear. In this paper, we reveal the effect of the hammering on the vibration and the sound radiation characteristics. The stress distribution within the cymbal produced by hammering is reproduced by thermal stress analysis and the change in natural frequency of the modes are calculated by the vibration analysis with the stress distribution. The change (i.e., increase or decrease) in natural frequency for each mode is explained by the stress and modal strain energy distributions.

著者

秋田 涼佑 梶原 逸朗 細矢 直基

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.343, 2016 (Released:2017-06-19)

---

This paper proposes a health monitoring system for detecting a hole opened on a pipe based on laser plasma acoustic excitation and acoustic measurement. In this system, the acoustic excitation is applied to the pipe by the laser-induced plasma in the air, which is generated by a high-power Nd: YAG pulse laser. Non-contact acoustic impulse excitation can be realized by laser-induced plasma. A microphone is used for measuring the time response of acoustic pressure. In this study, the detection of the hole on the pipe is focused. The time response of acoustic pressure changes due to reflection of acoustic wave caused at the hole opened on the pipe. The position of the hole is identified by applying continuous wavelet transform to time response of with/without the hole.

著者

小池 関也 見邨 康平

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2016 (ISSN:24242993)

巻号頁・発行日

pp.506, 2016 (Released:2017-06-19)

---

Previous studies, which calculate dynamic contributions of the whole-body joint torques to the generation of bat head speed by using the equation of motion for whole-body with bat system, showed that the motion-dependent term is the largest contributor to the generation of the bat head speed at the ball impact, and also showed that joint torques of the upper limb joints and the torso joint are the main contributors to the head speed with consideration of the generating factors of the motion-dependent term. These results do not tell us the roles of the lower limb joints in the bat head speed generating mechanism. So in order to quantify the roles of the lower limb joints in the mechanism, we quantify the dynamic contributions of the whole-body joint torques to the generation of forward/backward rotational motion of the lower trunk segment during baseball batting motion. Five collegiate baseball players participated in this experiment. They performed hitting a teed ball as strong as possible. Kinetic data of each hand and each foot were obtained by using an instrumented bat equipped with 28 strain gauges and 3 force platforms, respectively. From the results, the flexion/extension torque of both hip joints showed the largest contribution to the forward angular velocity of the lower trunk segment against the large negative contribution due to the torso joint torque. This result indicates that these hip joint torques play an important role to exert large rotational torque at the torso joint, and these hip joint torques show indirect contributions to the bat head speed.