Vibration analysis of non-uniform shaft-rotor system

Rotor dynamics is the study of the behaviour of the machines resulting from excitations originating from its rotating elements, and has a very important role to play throughout the fast-growing mechanical and industrial world. Shafts or circular cross-section beams are important parts of rotating systems and their geometries play important role in rotor dynamics. Therefore, there is a need to consider the dynamic characteristics of special shaft-rotor systems with disks and shafts whose radii are functions of their length. The procedures for the determination of the deflection slope, shear force and bending moment at the extremities of the shaft are used and the dynamics of shaft-rotor system are considered. Conventional frequency response method is used for the computation of resonance, critical speed or whirling frequency. For particular lengths and rotational speeds, the response of the system is determined for the establishment of the dynamic characteristics. Several types of such shaft-rotors are analysed as examples. Hollow tapered shaft-rotors with uniform thickness and uniform bore are also considered

Vibration Analysis of Convergent-Divergent Shaft-Rotor System

Abstrac

The influence of online resources on student–lecturer relationship in higher education: a comparison study

The internet has become a key resource for students’ higher education studies due to both its availability and currency. Previously within higher education, lectures, books and course materials were the only sources of information. This change, to more open access to information and more online materials being accessed outside of those provided by lecturers, and indeed institutions, is likely to accelerate and change the way students are learning. This study aims to help institutions understand better the impact of these changes on the student–lecturer relationship by exploring students’ perceptions of their studies in terms of power and students’ academic engagement in the classroom. The importance of the internet (online learning resources) to students’ achievements, the importance of lecturers and the student–lecturer relationship have all been widely investigated. However, limited research has been undertaken examining the impact of students’ use of the internet on the student–lecturer relationship, or comparing this across different countries and cultures. To address this, data were collected via semi- structured questionnaires distributed to undergraduate students from three countries: United Kingdom, Saudi Arabia and Kenya. Quantitative data were analysed using a simple statistical analysis approach and qualitative data were analysed using a thematic analysis approach. The results showed that students’ use of the internet has improved students’ academic self-confidence, academic self-reliance and student– lecturer connectedness, but students’ use of the internet has increased the gap in the student–lecturer expert relationship and referent relationship. The impact and rea- sons for this differed between the countries involved in this study

Finite Element Analysis of Fastener Joints in Metallic and Orthotropic Structures

Joints are essential to connect different components of a structure or sub-assemblies and they are inevitable in any large scale engineering structure. Among various methods of joining, fastener (pin) joints are common in cases where periodic assembly and dis-assembly are required. To understand the mechanism of load transfer in these joints, extensive studies have been made in the past. In the present work, NISA code for finite element analysis is made use to understand the mechanics of load transfer in such joints. The basic configuration considered is actually a pin in a plate for both metallic as well as orthotropic plates. Both the pin loading and plate loading cases have been studied. The effect of load parameter, stresses and type of fit namely push, clearance or interference on contact/separation angle have been studied and presented. The results obtained could be of immediate value to practical problems

Vibration Analysis of Hollow Tapered Shaft Rotor

Shafts or circular cross-section beams are important parts of rotating systems and their geometries play important role in rotor dynamics. Hollow tapered shaft rotors with uniform thickness and uniform bore are considered. Critical speeds or whirling frequency conditions are computed using transfer matrix method and then the results were compared using finite element method. For particular shaft lengths and rotating speeds, response of the hollow tapered shaft-rotor system is determined for the establishment of dynamic characteristics. Nonrotating conditions are also considered and results obtained are plotted