Topic: vibration Isolation.
it is research report contain with Title Page, Abstract, Introduction, Literature Review, Methodology, Results, Discussion, Conclusion, References.
Passive Vibration Isolation
Literature Review
Vibration Isolation
Vibration isolation is a
type which has its main structure primarily separated from the source. This is done to ensure that the overall vibration produced at the source is not transferred to the main structure of the system. Furthermore, there are different methods of isolation vibration and some of the methods mainly include rubber mounting installation and dampers which are done between the floor and machine or at the mechanical structure respectively. The summary analysis for the two typical sets mainly posed as shown in the diagram below. According to the records of Soong (1997), vibration isolator forms the vibration path by allowing the transmission of the vibrations, more so between the main structure and the vibration source and thus, contributing to the vibration suppression as the process goes on in the system. Thus, the entire analysis for the study represented as shown in the diagram below
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Figure showing the vibration transmission between the source and the receiver
Passive Vibration Isolation
Zhu, (2013) noted that there are various concerns which arises while using the conventional passive isolators and the problems are preferably more and more when mechanical coupling is used to support the load which has a linear stiffness. In this case, there is unavoidable limitation which need to be considered and taken into account as this plays a vital role in the determination of the required stiffness of all the vibration in the isolator system. This study also established that there are two main designs associated with the vibration isolator and they include the effective as well as the load capacity of the vibration isolation.
On the other hand Neils (2010) argues that large stiffness is a fundamental requirement in the isolator when designing systems which require adequate forces to offer maximum load support. This is important as the maximum force will help in reducing all the excessive deflections recorded in the structure. In this case, it is also important to consider the vibration isolation improvements and to achieve this low isolation stiffness is required. The low isolation stiffness will overlay help in reducing also the risks associated with the resonance frequency as well as the vibration transmissibility in the system. Thus, this study establishes that the low isolator stiffness is an important aspect which raises major constraints and concerns in the designing of the vibration isolation for the passive systems.
Linear Dynamic and Vibration Absorber
The study conducted by LIGO (2012) record a major constraint and concern regarding the conventional vibration isolators as far as the designing of the system is concerned. In this study, it is established that conventional isolators do not perform as the set standards when examined in all directions. The performances index is measured in line with the structural energy and mainly conducted for the systems which have more than one degree of freedom. LIGO (2012) also noted that spring-dampers have only the capability of working in attenuate vibration manner and the operations in the spring-dampers are only possible when carried along the damper and the spring. This constraint poses a major challenge when the spring-dampers are used in various advanced designs and systems. Some of the likely advanced applications which are expected suffer from the drawbacks include gravitational as well as the semiconductor manufacturing wave monitoring systems (LIGO, 2012). In the this study, it is established that the major drawbacks are recorded in the stringent multi-DOF which has vibration attenuation attached to the technique but have minimum impacts on the single DOF since they don’t have adequate vibration isolation. Thus, this figure below shows the various isolators which suffer imminently from the vibration attenuation in line with their operations (Sarban et al., 2011).
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Linear Dynamic and Vibration Absorber
Overlay, in the structures which have constant frequency as a result of steady and alternating forces, tends to take into consideration unpleasant vibration more so at the resonance end. Mead (1998) noted that dynamic vibration absorber or (DVA) one of the key examples which takes the unpleasant vibration under the passive vibration control classification. This study therefore establishes that the system has an auxiliary mass-spring and this helps in the neutralization of all the available vibrations attached to the structure. More, the DVA has broader applications worldwide and their application primarily classed under two distinct groups and these include neutralizers and the mass damper systems. According to Ting-Kong (1999), tuned mass DVA systems are those systems which have a tuning technique for handling the troublesome resonance while on the other hand neutralizer systems mainly associated with the excitation of the frequency problems and related issues. Notably, the natural frequency set in the system need to be tuned in a manner that it coincides with the overall unwanted frequency vibration with respect to the original system. Therefore, the system will be able to add more impedance to the existing primary structure and thereby, assisting in the absorption of all the vibration energy coming from the main structure (Le and Ahn, 2011).
Methodology
However, DVA systems have wider application in the engineering designs and structures and these applications are of advantageous in the long run. The DVA advantages are as a result of their ability incorporated and mobility which makes them to be absorbed at the final design stage in the structure. Therefore, dynamic vibration absorber is mainly used as a vibration reduction technique to reduce excessive structural and machine vibration levels. In this case, dynamic vibration absorber will protect the structures which have resonance frequency set at unpleasant level from any excited vibration. For instance, dynamic vibration absorber application can be applied in the designing and overall process of improving the effectiveness of the structure as shown in the diagram. In the application the DVA systems are used to set the optimum vibration levels for the structure so as to protect the structure from being subjected to the excessive vibrations which may in turn have imminent impacts on the its overall performance and stability ( Ito and Schitter, 2018 p.16).
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Figure showing the dynamic vibration absorber application
Methodology
Examining the Sound-absorbent Layers Vibrations
The methodology study mainly examined the acoustic materials as well as the barriers which the design likely to face when handing the aspects of the vibro-acaustics securities in the system. In handling this aspect, various design works, standards and material drawings are appraised in-depth in line with all the regulations of the vibro-acoustics AGH and the mechanical department. Furthermore, all the tests procedures are conducted at the preliminary stage and at the final stage of this research analysis with reference to the acoustic parameters. Also, the method aspect evaluates the absorptions related issues of sound as well as the overall application of the sound-absorbent layers in the design work. In this case, the core sound-absorbents are appraised on the basis of preliminary estimations and the physical sound absorption rates. Thus, the vibration check in line with the methodological aspects precipitated as shown in the diagram below and in accordance with PN-EN ISO 105334-2:2003 (Matichard et al., 2015).
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Figure showing all the steps used in examining the Sound-absorbent Layers Vibrations (Sun and Jing, 2015 p.150).
Analytical Evaluation of Vibration Isolation
In this case, the study is appraised using analytical aspect to attain all the vibration viability and the attenuation of the structural components. Although the methods apply to all the structures, in this scenario, the study mainly conducted for the light material components (Sun and Jing, 2015 p.150).
Therefore, the diagram represented below show the analytical model which can be used to examine vibration attenuation performance of the structures. The model not only has the sliding base plate, damping elements, rational behavior but also a spring elements. The model operates based on the rotational principle and thus, can be move in the three axial directions as the vibrations and the changes in the systems may require. Preferably, the models operations are grounded on the performance index and thus, have a decisive dynamic rotational behavior (Hoshino et al., 2015).
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Figure showing the model used in examining vibration attenuation
Moreover, the analytical method mainly uses the Nomenclature equation of motion is as follows.
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Thus, the computational equations for this analysis, mainly demarcated as shown below
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Results
From the analysis above, a response figures shown below can be obtained. This figure has both the vertical and horizontal waves at the left column as the primary inputs. Also, in the middle, there is horizontal acceleration, displacement as well as velocity. Additionally, there is right column, velocity, rotational acceleration, and displacement as well as vibration attenuation in the rear support. This results show that there is a reduced response of about ½ in line with structural components and this is compared to the existing horizontal maximum acceleration. Thus, the graphs below show the analysis for different structures, when they are subjected to the isolation vibrations ( Liu et al., 2015 p.55).
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Figure showing the wave and Isolation vibration test results (Sun, Gao, and Kaynak, 2015).
Discussion
The analytical method as well as models associated with the methodology is verified as far as the results are concerned. This scenario mainly occurs in situation whereby the UD 12.5kine level and the JMA Kobe 25kine applied as the input wave. In this analysis, values are obtained regarding the damping ratio as well as natural frequency from this experiment. The table below shows the obtained values and, it is from this model that minimum, maximum as well as RMS accelerations and their comparisons are appraised. Thus, this analysis shows that the investigative results and the overall experimental results are verified as far as the examination is concerned. Thus, the two graphs below shows the average comparison between the investigative and the experimental results (Rao and Yap, 2011).
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Conclusion:
In summary, the vibration attenuation regarding the isolation vibration is an important aspect which needs to be considered preferably. Thus, from the both experimental and analytical evaluation, one can conclude that reducing the overall vibration for the light-weight structure helps in increasing the effectiveness of the structural components and low-cost.
Vibration isolation is usually a process in which an object is isolated from the source vibrations, and such objects may include a piece of equipment. Vibration is considered undesirable in a variety of areas that is the livable spaces and built systems. Machinery failures and objectionable noise levels are often brought by high vibration levels, and the most common source of noise is typically the machines which are mounted on floors. The ground floor is generally the best place to install a vibrating machine. However, this has not been made possible, and this is caused by rotating devices which are mounted on the roof. Usually, the source of the vibration is the primary challenge which has hindered the mounting of machines on the ground floor. A critical related problem to vibration isolation is the machines which are vibration sensitive such as lasers, computer disk drivers, surgical microscopes and MRI units (Xiao, Jing. and Cheng, 2013).
References:
Guo, P.F., Lang, Z.Q. and Peng, Z.K., 2012. Analysis and design of the force and displacement transmissibility of nonlinear viscous damper based vibration isolation systems. Nonlinear Dynamics, 67(4), pp.2671-2687.
Hoshino, Y., Kobayashi, Y., Yoshida, D., Maeda, T. and Suzuki, S., 2015, May. Suppression of competitive pressure modes in a redundant actuators for a vibration-isolation table. In Control Conference (ASCC), 2015 10th Asian (pp. 1-6). IEEE.
Ito, S. and Schitter, G., 2018. Atomic force microscopy capable of vibration isolation with low-stiffness Z-axis actuation. Ultramicroscopy, 186, pp.9-17.
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