Kohei Furuya

An Application of Shape Optimization to Brake Squeal Phenomena

The present paper describes an application of non-parametric shape optimization to disc brake squeal phenomena. The disk brake squeal is known as self-excited vibration; the real and imaginary parts of the complex eigenvalue indicate the damping coefficient and natural angular frequency, respectively. The modes that have a negative damping coefficient cause disk brake squeal. Therefore, a main problem is defined as complex eigen value problem and a real part of the complex eigenvalue causing the brake squeal is chosen as an objective cost function for the shape optimization problem. For the solution to main problem which has a large number of DOF, component mode synthesis method adapting residual stiffness (CMS-R) is used in order to improve the accuracy of eigenpairs by conventional component mode synthesis method (CMS). The Fre ́chet derivative of the objective cost function with respect to the domain variation, which we call the shape derivative of the objective cost function, is evaluated using the solution of the main problem and the adjoint problem. A scheme to solve the shape optimization problem is presented using an iterative algorithm based on the H 1 gradient method for reshaping. For an application of the shape optimization method, a numerical example by using a practical disc brake model is presented. From the numerical result, the real part of the target complex eigenvalue monotonously decreases until it reach zero and effectiveness of CMS-R with regard to the shape optimization problem is presented.

Prediction of Static and Dynamic Mechanical Properties of GFRTP Product through Injection Molding

This paper aims at evaluating the prediction accuracy of macroscopic static and dynamic mechanical properties, including damping properties, of glass fiber reinforced thermo plastics (GFRTP) obtained via computer simulations. The prediction procedure is based on the Eshelby-Mori-Tanaka approach using fiber orientation tensor. The prediction accuracy of mechanical properties depends on the fiber orientation tensor. In this paper, we compare that prediction accuracies obtained using measured fiber orientation tensor and using simulated fiber orientation tensor by resin flow analysis. Additionally, we propose a linearized damping model based on the Eshelby-Mori-Tanaka approach and modal strain energy method to predict damping property, as well as a method for evaluating the contribution of the elastic modulus in order to quantitatively comprehend the anisotropic characteristics of GFRTP.

Vibration Reduction of Brush Cutter

Brush cutter powered by engine has been widely used on a daily basis for mowing of road shoulders and gardens. People who regularly operate brush cutter are at risk of developing Raynaoud’s disease due to large vibration. Such vibration disorder can be prevented by reducing the handle vibration by good use of structural modification. In this study we focused on rubber bushes which support the drive shaft in pipe to transmit the engine power to the cutting blade. First the dynamic characteristics of the brush cutter such as Operational Deflection Shape are grasped and then the hardness and the placement of rubber bushes are optimized to reduce the handle vibration effectively.

Biomechanical analysis for the epidural needle insertion

In order to test the hypothesis about reduction in the deformation of the ligamentum flavum due to tension inside the ligamentum flavum, nonlinear finite element (FE) analysis was employed. As a preliminary analysis of natural tissue, nonlinear FE analysis was applied to a rubber plate. Assuming that the rubber is third-order Mooney-Rivlin model, the analysis and the experimental curves overlap with each other until pierced point. The maximum major strain calculated by FE analysis was feasible to predict pierced point. To apply nonlinear FE analysis for the porcine ligamentum flavum, the Mooney-Rivlin coefficient of the porcine ligamentum flavum was identified from the tensile test data. Assuming that the sharp bar pierced the ligamentum flavum when the maximum major strain reached a constant value, the required displacement became shorter by 1.0mm by applying the initial tension.

Experimental Transfer Force Identification by Dynamic Stiffness Method and Reduction of Engine-Frame Coupled Vibration Based on Identified Force

In this paper, focusing on the coupled vibration of light weight vehicle engine and frame, the efficient method to reduce the vibration is discussed. First, target coupling vibration is explained by experimental data. And transfer force identification which transmits from the engine to the frame through the engine mount is carried out using dynamic stiffness method. In order to explain how the engine and the frame are coupling, the coupling index is introduced. The index is defined by inner products of the identified force and the frame FRF. Finally, the method to reduce the coupling index by adjusting the engine mount angle is proposed. The optimal adjustment angle is predicted and modifying the angle in experiment, it is shown that the adjustment method can reduce the coupling index and coupled vibration.

Experimental Realization of System-Level Vibration by Use of Single Component Based on Virtual Boundary Condition Concept

In order to meet the requirement of less vibration and less noise of complex machine, such as automobile, the system-level vibration test is carried out in spite of huge cost and time, which is conducted only when all components are able to be assembled. Although the vibration of individual component alone is different from the system-level, but a sophisticated component test is aimed to realize the system-level vibration at early development stage.

CAE Based Approach to Understand a Behavior of Vibro-Acoustic System

In this paper, a CAE based approach to understand a behavior of vibro-acoustic system is introduced. The sound pressure at an evaluation point in an enclosure can be described by inner product of (i)an acoustic transfer function from coupling surface to the evaluation point, and (ii)a structural vibration on the coupling surface. By addition of (iii)the correlation angle between above (i) and (ii), the sound pressure can be exactly estimated. In this paper, the correlation (iii) is called Vibro- Acousitc Coupling Factor (VAC). Using VAC, it is possible to understand not only the radiation efficiency, but also the interference of sound at the evaluation point. The proposing method explains the behavior of vibro-acoustic system using the frequency response of (i), (ii) and (iii). As an example, the proposing method is applied to FE model for improving the vibroacoustic characteristic.