{"title":"Vibration and stability of time-dependent translating media","authors":"W. D. Zhu","doi":"10.1177/058310240003200502","DOIUrl":"https://doi.org/10.1177/058310240003200502","url":null,"abstract":"This article reviews some recent advances in the analysis of vibration and stability of linear, time-dependent translating media. Three problem areas are discussed: translating media transporting payloads, translating media with variable speed, and translating media with variable length. Previous research and basic governing equations are briefly reviewed. New methodologies developed by the author and others are highlighted, followed by a summary of major findings and possible directions for future research. The principal focus is on the intrinsic dynamic characteristics associated with distributed linear models of time-dependent translating media.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131915730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Active-Materials Induced-Strain Actuation for Aeroelastic Vibration Control","authors":"V. Giurgiutiu","doi":"10.1177/058310240003200501","DOIUrl":"https://doi.org/10.1177/058310240003200501","url":null,"abstract":"Recent achievements in the application of active- materials induced-strain actuation to counteract aeroelastic and vibration effects in helicopters and fixed wing aircraft are reviewed. First, the induced-strain actuation principles and capabilities are briefly presented. Next, the attention is focused on the smart rotor blade applications. Induced twist, active blade tip, and active blade flap are presented, with emphasis on experimental results. Then, fixed wing aircraft applications are considered. Experiments of active flutter control, buffet suppression, gust load alleviation, and sonic fatigue reduction are discussed. Conclusions and directions for further work are presented.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115086708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Vibration of flexible rotating disks","authors":"I. Shen","doi":"10.1177/058310240003200401","DOIUrl":"https://doi.org/10.1177/058310240003200401","url":null,"abstract":"Rotating disks are key components of many rotating machines, such as computer hard disk drives, circular saws, and disk brakes for automobiles and aircraft landing gears. Mathematical models of these systems consist of four elements: disks, spindles, bearings, and sliders. Depending on the application, the disks, spindles, and bearings can be modeled as rigid or flexible. The sliders are often modeled as a stationary spring-mass-dashpot system in contact with the rotating disks. This paper reviews recent vibration research on single and multiple flexible rotating disks interacting with spindles, bearings, and sliders. Systems with rigid rotating disks are not included in this review.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122497566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nonlinear Vibration of Cracked Structures: Perspectives and Horizons","authors":"J. Brandon","doi":"10.1177/058310240003200402","DOIUrl":"https://doi.org/10.1177/058310240003200402","url":null,"abstract":"Until recently, research in the modeling of nonlinear structures has either been too simplistic in its approach, for general structures, or too context specific, for particularly vulnerable structures, to devise general guidelines. Increasing the understanding of the effects of flaws in structures and their characteristic behavior patterns enables practical implementation of condition-monitoring techniques. It is only possible for these techniques to be exploited effectively if the most likely position and severity of these defects can be predicted from knowledge about the design and construction of the systems under test.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133142545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stochastic linearization technique : A new interpretation and a selective review","authors":"I. Elishakoff","doi":"10.1177/058310240003200301","DOIUrl":"https://doi.org/10.1177/058310240003200301","url":null,"abstract":"Several developments in stochastic linearization are summarized in this review paper, along with the new, statistical orthogonality-based derivation of the method. A nonlinear oscillator subjected to colored noise is examined, the case of nonlinear damping is discussed, and the true stochastic linearization technique is described. The results of the latter match the exact mean square responses of a nonlinear structure. A combination of stochastic linearization with the Monte Carlo method is outlined. In addition, the accuracy of an energy linearization technique versus the newly interpreted classical scheme is examined for a Duffing oscillator subjected to white or colored noise excitations. The results obtained by the two schemes are compared in terms of percentage-wise error relative to the exact solution or relative to numerical results obtained through Monte Carlo simulation. These applications confirm the superiority of the energy linearization technique over the force linearization technique in several examples considered. In certain circumstances, however, namely for some nonlinear softening oscillators, newly interpreted conventional linearization may yield more accurate results. The method of weighing functions improves the accuracy of both methods.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127554441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A tutorial on design analysis for random vibration","authors":"G. Reese, R. Field, D. Segalman","doi":"10.1177/058310240003200602","DOIUrl":"https://doi.org/10.1177/058310240003200602","url":null,"abstract":"The von Mises stress is often used as the metric for evaluating design margins, particularly for structures made of ductile materials. While computing the von Mises stress distribution in a structural system due to a deterministic load condition may be straightforward, difficulties arise when considering random vibration environments. As a result, alternate methods are used in practice. One such method involves resolving the random vibration environment to an equivalent static load. This technique, however, is only appropriate for a very small class of problems and can easily be used incorrectly. Monte Carlo sampling of numerical realizations that reproduce the second order statistics of the input is another method used to address this problem. This technique proves computationally inefficient and provides no insight as to the character of the distribution of von Mises stress. This tutorial describes a new methodology to investigate the design reliability of structural systems in a random vibration environment. The method provides analytic expressions for root mean square (RMS) von Mises stress and for the probability distributions of von Mises stress which can be evaluated efficiently and with good numerical precision. Further, this new approach has the important advantage of providing the asymptotic properties of the probability distribution. A brief overview of the theoretical development of the methodology is presented, followed by detailed instructions on how to implement the technique on engineering applications. As an example, the method is applied to a complex finite element model of a Global Positioning Satellite (GPS) system. This tutorial presents an efficient and accurate methodology for correctly applying the von Mises stress criterion to complex computational models. The von Mises criterion is the traditional method for determination of structural reliability issues in industry.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126149033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph James Duffy, J. Rooney, B. F. Knight, C. Crane
{"title":"A review of a family of self-deploying tensegrity structures with elastic ties","authors":"Joseph James Duffy, J. Rooney, B. F. Knight, C. Crane","doi":"10.1177/058310240003200202","DOIUrl":"https://doi.org/10.1177/058310240003200202","url":null,"abstract":"A review of a family of tensegrity structures that self-deploy from a stowed or packed configuration is presented. In the packed configuration, the mechanism is of a cylindrical form with the struts lying side by side. Such structures may be applied in the deployment of antennas in space and in the rapid deployment of shelters or tents. This family of structures evolved from a study of in-parallel platforms with compliant legs or connectors. A number of relevant references are cited.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"238 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124602198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An overview of active magnetic bearing technology and applications","authors":"M. Kasarda","doi":"10.1177/058310240003200201","DOIUrl":"https://doi.org/10.1177/058310240003200201","url":null,"abstract":"In this paper, the author presents a short history and general discussion of the operation of an active magnetic bearing, as well as specific applications of active magnetic bearings in both commercial and research scenarios. Although magnetic suspension devices have been used in nonrotating scenarios such as magnetically levitated trains, only applications associated with rotating equipment will be addressed. Commercial applications such as large turbomachinery and small-scale turbomolecular pumps will be discussed. Research applications, such as bearingless motors, flywheels for energy storage, micromachines, and biomedical applications, will be presented. Research topics associated with superconducting magnetic bearings are beyond the scope of this paper.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130056433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kurtosis as a metric in the assessment of gear damage","authors":"V. Rao","doi":"10.1177/058310249903100601","DOIUrl":"https://doi.org/10.1177/058310249903100601","url":null,"abstract":"Gear diagnostics is becoming an important area of research, especially in critical applications such as rotorcraft propulsion where safety is paramount. Many rotorcraft statistics illustrate the need for dedicated monitoring systems to reliably diagnose the faults. A gear system fails when it ceases to efficiently perform the function for which it was designed. This can be the result of a single catastrophic event or an accumulation of initially undetected and rather innocuous events in the gear system. It is well known that evaluation of statistical properties will give reasonable diagnostic indication of gear damage. Although there are a large number of such statistical attributes such as root mean square value, crest factor, skewness, kurtosis, and so on, kurtosis has emerged as a single number metric and one of the good indicators of damage of gears. Kurtosis can be estimated in both the time domain and the frequency domain. This paper discusses various variants of the kurtosis parameter such as FM4, NA4, NA4 * , NB4, and NB4 * , as well as their relative importance. The ability to use kurtosis beta distribution to detect toothwise gear faults is also discussed.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130108204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PC-based analysis of turbomachinery vibration","authors":"R. G. Kirk, K. Raju, K. Ramesh","doi":"10.1177/058310249903100602","DOIUrl":"https://doi.org/10.1177/058310249903100602","url":null,"abstract":"This paper documents the development of a PC-based analysis system that is simple to implement and has an efficient method for presentation of results. The system is composed of several modules that are based on industry-proven capabilities that were originally mainframe programs (in addition to several newly developed programs) and a user-friendly control program that increases the probability of proper data entry and modification. The results of rotor response to unbalance or complex damped eigenvalues can be animated for a never-before-available opportunity to fully understand and observe forward and backward whirl, mixed modes, and the dynamic mode shapes of the turbomachinery.","PeriodicalId":405331,"journal":{"name":"The Shock and Vibration Digest","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124608445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}