Papers by Keyword: Vibration Testing

Abstract: In the recent scenario, the focus for the environmental pollution and the piling of products from non-renewable and non-biodegradable resources has forced many researchers to develop new eco-friendly and biodegradable materials. In this work, banana fiber reinforced hybrid polymer matrix composite is fabricated and tested. Banana fiber is treated with various alkali solutions to modify surface properties in order to improve mechanical properties. Hybrid polymer is made from CNSL (Cashew Nut Shell Liquid) and Isotholic Polyester. Dynamic behavior of banana fibre reinforced hybrid polymer matrix composite is investigated by means of experimental and finite element analysis. Simulation of frequency response and dynamic displacement are carried out on banana fibre reinforced hybrid polymer matrix composite by ANSYS and it is compared with experimental results. Optimization of design parameter is carried out using ANOVA technique and design of experiment of Taguchi method is employed for better combination of the parameter.

Abstract: This paper presents a numerical algorithm technique to detect cracks propagated in concrete beams based on the frequency response curve of the beam determined from vibration testing. Impact tests on simply supported reinforced concrete beams were conducted to measure vibration on the beam. The ICATS software was carried out to capture the Frequency Response Functions (FRFs) data at each load step. Utilizing the FRFs data, a numerical algorithm based on finite different methods was performed to compute the different FRFs between undamage and damage beams based on the mode shape curvature square (MSCS) method. The numerical damage location was defined by subtracting the MSCS undamage to damage of beams. Therefore, the accurate damage location was identified by comparing the numerical and observed experimental results.

Abstract: Chiral sculptured thin films (STFs) Glancing-angle deposition (GLAD) thin films are nanoengineered to meet the requirements of a variety of applications such as micro filters, sensors, and waveguides due to their unique frequency characteristics which cannot be achieved by conventional solid materials. For the design, it is necessary to understand the elastic properties of STFs. To facilitate this, we report on our newly developed advanced micro-scale vibration testing process. In the testing, specially designed micro-specimens with surface areas of tens by tens of microns are excited using a piezoelectric (PZT) actuator and the resonance frequencies are detected by a laser device in the vertical or lateral directions successfully. The anisotropy elastic modulus of STFs composed of helical nanosprings are identified on the basis of vibration testing. The thin film shows strong characteristic anisotropy that the solid one hardly can attain. The micro-scale testing technique can be extended to other materials and microstructures.

Abstract: The coal transport trestle as a connection channel is widely used in large and medium-sized coal enterprises, which plays an important role in the whole manufacturing process. The vibration problems in coal transport trestle can not only reduce the occupant comfort, cause people serious harm, but also have pernicious effect on structure. Along with the structure aging and dynamics property change, things go badly, which even causes enormous life and property loss. This paper describes the vibration testing and analysis methods of the steel truss coal trestle though engineering examples. The results show that the belt transport system is the main reason which caused the vibration of the STCT, and trestle must undergo resonance phase with the exciting force changes.

Abstract: The vibration measurement is one of the new application in the optical sensor. This paper studies a new non-contact optical vibration sensor, and implements the Optical fiber vibration sensor based on FPGA. The totally available measurement range arrived over 300um, and the accuracy of 0.1 um can be obtained . This fiber optic vibration sensor has a low cost, good reliability, and high accuracy measurements.

Abstract: It is a common practice in the automotive industry to expose products to accelerated vibration tests, that simulate the load, predicted to occur during the products service time. To avoid long testing times, higher amplitudes are used. Usually such tests come late in the development process, and can result in unexpected costs. A common tool for predicting time-to-failure or expected fatigue-life of the product is the time-domain method, using the rainflow counting algorithm and the Palmgren-Miner summation method. However, if one chooses to apply this method inside a FEM environment on a large amount of nodes with different time histories dependent on the structure excitation, the time-domain method becomes computationally complex. This has led to more effective methods, that estimate the time-to-failure in frequency-domain but are less accurate, compared to the time-domain approach. In this research, a group of such methods is presented and compared using real signals, namely: Tovo-Benasciutti, Wirsching-Light, Petrucci-Zuccarello, empirical α_0.75, Dirlik and Gao-Moan method. Separately, only some of those methods were already compared side by side. Usually the comparison was made on simulated random signals, while this research compares them based on a real signal, collected by measuring different groups of spectra (e.g. typical vibration test profiles, different background noise levels, spectral width, number of modes etc.). In existing studies, Dirlik is usually identified as most accurate but in this research, conclusions show, that the Tovo-Benasciutti and Zhao-Baker methods can be more accurate than the Dirlik method and should therefore also be considered for vibration fatigue analysis.

Abstract: Based on UG and ADAMS software, the virtual prototype of a large wind turbine is established in this paper. Through the dynamic simulation of wind turbine tower, the time domain and frequency domain of vibration acceleration of X and Y direction on tower is obtained and compared to the actual measured data. The analysis results provide a theoretical basis for optimal structure design and further improvement of wind turbine.

Abstract: The study of the thesis is based on advanced vibration testing and pressure testing equipment; we can get accuracy test data including shaft vibration, radial vibration, and the pressure of printing and other parameters. Mackling Rails quantitative is descripted by self-made module, combined with the test data of the mechanical parameters; I establish corresponding relationship between Mackling Rails and dynamic characteristic parameters of printing machinery, which provide a method to get rid of relying solely on experience. It makes Mackling Rails detection more convenient and reliable. Solutions introduced in the thesis also apply to other fault of the press.

Abstract: This paper introduces the omnidirectional vibration sensor based on MEMS three accelerometer, which is used to solve the problem that the tradition vibration sensor cannot acquire multidimensional vibration signal effectively, on the background of underground distributed passive localization.It has MEMS accelerometer as the core detection unit, including three dimensional vibration detection unit, signal conditioning unit and power supply unit. It adopts the spherical shape ,which consists of Aluminum shell、Potting material of Epoxy resin and Multilayer circuit board. By means of finite element analysis and Field test, it shows that this sensor can effectively get omnidirectional vibration signal vector information, and the engineering application value is great.

Abstract: A Control Moment Gyroscopes (CMG) is a torque generator for attitude control of a high resolution and high agility satellite without any increase in power, mass or volume. In this paper, a new support structure of the CMG is proposed. According to the configuration idea of the CMGs, the original design model of the support structure is established. Furthermore, the topology optimization is performed by the FEM software ANSYS and after that came up with a suitable layout of the support structure of the CMG. Based on the optimized design results, the 3D models of the CMG and its support structure are established by the 3D design software Pro/E. Frequency of the assembly is analyzed and calculated. Finally, took the launch dynamics environments into consideration, the vibration testing are carried out to verify the rationality of the new design structure.