A comprehensive review on modal parameter-based damage identification methods for beam- or plate-type structures is presented, and the damage identification algorithms in terms of signal processing...

Vibration-based Damage Identification Methods: A Review and Comparative Study:

The octopus is a marine animal whose body has no rigid structures. It has eight arms composed of a peculiar muscular structure, named a muscular hydrostat. The octopus arms provide it with both locomotion and grasping capabilities, thanks to the fact that their stiffness can change over a wide range and can be controlled through combined contractions of the muscles. The muscular hydrostat can better be seen as a modifiable skeleton. Furthermore, the morphology the arms and the mechanical characteristics of their tissues are such that the interaction with the environment (i.e., water) is exploited to simplify control. Thanks to this effective mechanism of embodied intelligence, the octopus can control a very high number of degrees of freedom, with relatively limited computing resources. From these considerations, the octopus emerges as a good model for embodied intelligence and for soft robotics. The prototype of a robot arm has been built based on an artificial muscular hydrostat inspired to the muscular ...

Soft Robot Arm Inspired by the Octopus

Brittle failure of components weakened by cracks or sharp and blunt V-notches is a topic of active and continuous research. It is attractive for all researchers who face the problem of fracture of materials under different loading conditions and deals with a large number of applications in different engineering fields, not only with the mechanical one. This topic is significant in all the cases where intrinsic defects of the material or geometrical discontinuities give rise to localized stress concentration which, in brittle materials, may generate a crack leading to catastrophic failure or to a shortening of the assessed structural life. Whereas cracks are viewed as unpleasant entities in most engineering materials, U- and V-notches of different acuities are sometimes deliberately introduced in design and manufacturing of structural components. Dealing with brittle failure of notched components and summarizing some recent experimental results reported in the literature, the main aim of the present contribution is to present a review of some local approaches applicable near stress raisers both sharp and blunt. The reviewed criteria allowed the present authors to develop a new approach based on the volume strain energy density (SED), which has been recently applied to assess the brittle failure of a large number of materials. The main features of the SED approach are outlined in the paper and its peculiarities and advantages accurately underlined. Some examples of applications are reported, as well. The present review is based on the authors’ experience over more than 15 years and the contents of their personal library. It is not a dispassionate literature survey.

Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches

Due to the inherent nonlinear nature of magnetorheological (MR) dampers, one of the challenging aspects for developing and utilizing these devices to achieve high performance is the development of models that can accurately describe their unique characteristics. In this review, the characteristics of MR dampers are summarized according to the measured responses under different conditions. On these bases, the considerations and methods of the parametric dynamic modelling for MR dampers are given and the state-of-the-art parametric dynamic modelling, identification and validation techniques for MR dampers are reviewed. In the past two decades, the models for MR dampers have been focused on how to improve the modelling accuracy. Although the force–displacement behaviour is well represented by most of the proposed dynamic models for MR dampers, no simple parametric models with high accuracy for MR dampers can be found. In addition, the parametric dynamic models for MR dampers with on-line updating ability and the inverse parametric models for MR dampers are scarcely explored. Moreover, whether one dynamic model for MR dampers can portray the force–displacement and force–velocity behaviour is not only determined by the dynamic model itself but also determined by the identification method.

https://iopscience.iop.org/article/10.1088/0964-1726/20/2/023001/pdf

Magnetorheological fluid dampers: a review of parametric modelling

Dean of Undergraduates John Hutchinson, the General Council and President David Leebron assembled the Working Group on University Responses to Federal Initiatives on Sexual Assault in June, according to Associate Vice Provost Matthew Taylor. The group formed in order to address federal measures as well as to continue changes already in progress. The federal government began releasing guidelines on how universities and colleges should address sexual assault beginning in April 2014. The White House task force report, Not Alone, features certain recommendations regarding training, prevention and adjudication of sexual assault. “The working group is looking at Rice’s policies, processes and communications about sexual violence and sexual harassment, in light of what the government is either recommending or requiring to make sure that we have a clear sense of the areas in which,” Taylor said. “We either exceed the recommendations or there are things that we need to do to meet the recommendations.” The working group consists of both undergraduate and graduate representatives, as well as leadership from the Student Wellbeing Office, Student Judicial Programs, the Rice University Police Department, the Rice Counseling Center, Athletics and Graduate and Post-Doctoral Studies, among others. There are approximately an equal number of males and females in the group. “I wouldn’t say [we have had] findings yet,” Taylor said. “We have tried to educate ourselves on the government’s recommendations.” According to Taylor, the working group focused on immediate shortterm issues for the summer. Many of the federal recommendations were already being met by Rice, and several aspects were already undergoing changes before the formation of the working group. Before the working group was formed, Associate Dean of Undergraduates Donald Ostdiek had already decided to hire a Title IX Resource Navigator, who will help students navigate the investigation if they choose to come forward and report a sexual assault. The main efforts of the working group are directed towards meeting federal guidelines that state that universities should designate employees to whom students can report sexual assault in confidence. Taylor said although Rice already has designated individuals, the policy’s language did not clearly outline whether those individuals are Title IX officers, responsible employees or non-disclosing employees. He said the new language encourages individuals to report cases. “The Title IX officers, in most cases, don’t have to report a student’s name, but we make it equally fair that, in some cases, the university would have to take action based on the law,” Taylor said. “Some of the people that we know students are most likely to go to for advice after a sexual assault are college masters, resident [associates] and college coordinators. We make it clear that they are responsible employees [who are] required to notify one of the Title IX coordinators if they are alerted by a student to a case of sexual assault or sexual violence.” Director of the Center for Student Wellbeing Kate Noonan and Wellbeing Advisor Saralyn Hernandez also contributed to the working group. Hernandez and Noonan said the Wellbeing Advisors are committed to providing trauma-informed support to students who have experienced sexual misconduct. “For survivors who prefer offcampus resources, Rice contracts with the Houston Area Women’s Center, [which] can provide support to Rice students outside the hedges,” Noonan and Hernandez said. Currently, new students undergo training during Orientation Week through Project Sexual Assault-Free Environment, presented by the Houston Area Women’s Resource Center and the Student Wellbeing Office. Although the working group did not have any influence on this year’s presentation of Project SAFE, the presentation already met federal recommendations by focusing on bystander prevention. The presentation discussed non-disclosing and responsible employees, although it did not talk about consequences for potential perpetrators. Colin Losey, a Martel College sophomore who transferred from the University of Chicago, said although he thought the presentation itself was satisfactory, he did not feel that all of the options for victims of sexual assault were covered, especially the option to report to police outside the university. “I’m a transfer student from a university that was recently hit with a major Title IX investigation, and a lot of what has come out from that is that the university’s adjudication process was used in a way to keep things internal,” Losey said. “Given what has happened at other college campuses across the country, students should be clear that this is criminal behavior, and they can press criminal charges.You don’t need to contact Rice first, and Rice need not be involved.” However, Taylor said offering Project SAFE only during O-Week is unsatisfactory and that there must Honor Council removes undergraduates from graduate cases, violates constitution

A new generation.

Crack detection in simply supported beams without baseline modal parameters by stationary wavelet transform

Design, modelling and testing of magnetorheological (MR) dampers using analytical flow solutions

This paper describes initial investigations into the behavior of a mechanical system for a proposed novel energy harvesting device. The device comprises a clamped–clamped beam piezoelectric fiber composite generator with side mounted cantilevers. These side mounted cantilevers are tuned by added masses to be resonant at different frequencies. A Rayleigh–Ritz model has been developed to predict the vibration response of the device and results from this model and from the real system are compared. The mechanical aspects of the device show a wide band energy harvesting characteristic in comparison to a single cantilever piezoelectric harvester.

https://iopscience.iop.org/article/10.1088/0964-1726/19/9/094009/pdf

S. Olutunde Oyadiji

Papers

Crack detection in simply supported beams without baseline modal parameters by stationary wavelet transform

Design, modelling and testing of magnetorheological (MR) dampers using analytical flow solutions

Design of a multiresonant beam for broadband piezoelectric energy harvesting

Application of MR damper in structural control using ANFIS method

Detection of cracks in simply-supported beams by continuous wavelet transform of reconstructed modal data