Papers by Keyword: Modal Analysis

Abstract: The vibration characteristics of the tendon-based parallel robot for processing are presented. Firstly, the free vibration equations of the robot on the stable position and orientation were modeled, and secondly the natural frequencies were deduced from the transformation of principal coordinates into modal coordinates. Next, cutting-force model was introduced and the solutions of the forced vibration equations were obtained from the Runge-Kutta method, where the minimum natural frequency was taken as basis of the time step that was important for computation convergence. Lastly, the algorithm was verified by simulations, also including solution transformation of time domain into frequency domain by Fast Fourier Transformation (FFT). The vibration properties could be manifested clearly by the solutions in frequency domain. The results show that the eccentricity and the mass of the moving platform are the important factors to make system instable in certain excitation frequency.

Abstract: Using the basic finite element theory, 3D finite element models of flexible membranous disc coupling with different disc thickness is built by ANSYS ，and then the dynamic characteristics are analyzed in working conditions. In particular, the analysis of static stress and harmonic response to the thickness of 0.85 model is done for getting the stress variation under a rated condition. The date calculated by dynamic characteristics and stress analysis can satisfy the design requirements. Those researches and analysis provide a theoretical consideration for complex vibration situation of flexible membranous disc coupling and for the improvement and optimization of coupling product.

Abstract: The effects of spindles vibrational behavior on the stability lobes and the Chatter behavior of machine tools have been established. The service life has been observed to reducethe system natural frequencies. An analytical model of a multi-segment spinning spindle, based on the Dynamic Stiffness Matrix (DSM) formulation, exact within the limits of the Euler-Bernoulli beam bending theory, is developed. The system exhibits coupled Bending-Bending (B-B) vibration and its natural frequencies are found to decrease with increasing spinning speed. The bearings were included in the model usingboth rigid, simply supported, frictionless pins and flexible linear spring elements. The linear spring element stiffness is then calibrated so that the fundamental frequency of the system matches the nominal value.

Abstract: In order to understand the dynamic characteristics of 16V240 type diesel, established its solid model and finite element model. And conduct the modal analysis of 16V240 diesel with Lanczos method to get the natural frequencies and vibration mode. And then, find the weak points of 16V240 diesel for its structural redesign and improving.

Abstract: To study the vibration characteristics of a ship engine-base system, modal analysis is carried out to get the natural frequency and principal modes of the engine-base system. On that basis, the dynamic stiffness of base is further discussed and the dynamic displacement is calibrated in engineering field by superposition principle. Calculation shows that the base stiffness satisfies the requirement practical use, and likewise, the vibration characteristics of the base meet the design requirements.

Abstract: To reduce the noise and vibration of mobile wastewater treatment plant, this paper presents testing and analysis of 50 measuring points in the working state of mobile wastewater treatment plant based on TST test analysis system. The structure’s natural frequency, damping and modal vibration modes are extracted within the frequency band of 0-1000HZ. By comparing the operating modal and the finite element modal, it is believed that the operating modal can accurately recognize modal parameters of the container.

Abstract: Based on the virtual prototype technology, using the ADAMS vibration analysis module, the displacement response rule of the main mechanism of the cutting system excited by sinusoidal harmonic excitation is obtained. And through the analysis of the results, the fact that 20HZ, 29HZ, 120HZ and 134 HZ are the sensitive frequency of the main mechanism is found out. Using the hammer test modal analysis methods to analysis cutting system of EBZ-75 type boom-roadheader, and compared with simulation results, the sensitive vibration frequency in vertical direction of the cutting system is achieved, which provides a test reference data for the optimize design of the cutting system.

Abstract: Modal frequency distribution of automotive structures or sub-structures is an important factor affecting the NVH performance. During lightweight optimizations of a part, the modal characteristics of the new design is often kept the same as those of the reference design to ensure that the NVH performance is not degraded. However, the effects of the part manufacturing process on the modal parameters are usually ignored in the design stage. In this study, four alternative designs of replacing the original steel hood of a passenger car with lightweight aluminum material are proposed. The stamping process (drawing, trimming and springback) of the inner and outer panels of the hood with both steel and aluminum designs is simulated in DYNAFORM. Once the residual stress, residual strain and thickness change of the panels during the stamping process are identified, a modal analysis is conducted on the four alternative designs. The obtained natural frequency data are compared with the natural frequencies of the body-in-white as well as the common excitation frequencies of the engine. It is shown that, due to parameter changes in the stamping process, the modal frequencies of the final manufactured part drift away from the original design before stamping. It is thus critical to take stamping effects into account when determining the optimal lightweight design of the hood.

Abstract: The characteristics of three-order elliptical gear is analyzed. The parameters of three-order elliptical gear are chosen and calculated. The three-dimensional solid modeling of three-order elliptical gear is achieved. The dynamic model of three-order elliptical gear is established by FEM and modal analysis of three-order elliptical gear is investigated. The natural frequency and major modes of the first six orders are clarified. The method and the result facilitate the dynamic design and dynamic response analysis of high-order elliptical gear.

Abstract: The car body-in-white as the core research objects, NVH performance based on white body in finite element modeling and numerical modal analysis, this paper finds out the natural frequency of vibration may cause the BIW’s resonance. It indicates the direction to improve body-in-white NVH performance, local stiffness and further structural optimization through testing modal, stiffness analysis and NTF / VTF experiments to validate the numerical results of the modal analysis of the credibility and the body-in-white how much frequency or frequency band resonance peak caused by the body.