FUNDAMENTALS OF THE DESIGN OF FUNDAL MANDRELS FOR THE INSTALLATION OF THIN-WALLED WORKPIECES. PART 1

There are a number of problems in mechanical engineering technology. One of them is related to the installation on the machine and the previous processing of thin-walled rings, which are widely used in mechanical engineering. Due to the low bending stiffness of thin-walled rings after processing there are a large magnitude of rigidity of the form (deviation from roundness). As production experience has shown, in the conditions of mass production, it is advisable to use fungal mandrels and adjustments to reduce shape errors. They allow for a small radial gap between the holes of the ring and the fungal cam to have extended contact rings with cams along the angular coordinate. However, there are no methods for calculating the parameters of contact interaction with cams, considering a number of factors, primarily the radial clearance. Hence, it is impossible to calculate more accurately the error of the form after processing. In this paper (it is supposed to be continued), based on methods for calculating flat rings of construction mechanics of machines, a method for determining the stress-strain state of a thin-walled state is proposed, considering the contact pressure. In this case, the semiangle of contact of the ring with the fungal cam and the shape of the contact pressure plot are determined. This allows you to calculate the stress state of the thin-walled ring and the shape error when processing more accurately in a fungal mandrel, as well as reasonably assign the dimensions of the mandrel parts. Due to the exceptionally large number of calculations in the calculations according to the proposed method, it can only be implemented using a computer program, which creates great difficulties in analyzing different source data. Therefore, it is planned to rework the completed developments into an engineering calculation method with graphs in dimensionless form.

Active Approaches to Vibration Absorption through Antiresonance Assignment: A Comparative Study

Vibration absorption is a core research topic in structural dynamics and the mechanics of machines, and antiresonance assignment is an effective solution to such a problem in the presence of harmonic excitation forces. Due to recent developments in the theory of feedback control systems, the use of active control approaches to antiresonance assignment has been recently gaining more attention in the literature. Therefore, several methods exploiting state feedback or output feedback have been proposed in recent years. These techniques that just rely on servo-controlled actuators are becoming an interesting alternative to active approaches that emulate the well-known Tuned Mass Damper in an active (or semi-active) framework. This paper reviews and compares the most important approaches, with a greater focus on the methods exploiting the concept of control theory without adding new degrees of freedom in the system. The theoretical results, with the underlying theory, are discussed to highlight the key features of each assignment techniques. Several numerical examples where different techniques are applied and compared, also providing some analysis usually neglected in the literature, enrich the paper and demonstrate the key concepts.

Mechanical and mathematical research of local deformations of a steel roller shell with a variable geometry of contact surface

The article is devoted to solving the fundamental and applied problem of nonlinear structural mechanics of machines by introducing into the drum two additional stop cylinders with supporting rollers at the end and adjustable length, providing a given elliptical or circular shape of a flexible shell with a smoothly variable geometry in the area of its contact with compacted pavement material. Compaction of soil, gravel and asphalt concrete in the sphere of road is not only an integral part of the technological process of the roadbed, road foundation and surface construction, but it is actually the main operation to ensure their strength, stability and durability. The quality, cost and speed of road construction, the possibility of using fundamentally new technologies, structures and materials is largely determined by the availability of modern road machinery.

Application of Problem Based Learning in Mechanics of Machines Course

The predominant educational methods in engineering education follow traditional classroom teaching, with some elements of tutorials and lab work. Although, there has been a growing tendency in recent years to introduce elements of active learning, and in particular problem-based (PBL) and project-based learning (PjBL). The paper reports on an attempt to use PBL in a topic on kinematics analysis of planar linkages, in a 3-credit course on Mechanics of Machines, offered in Year 3 of a 5-year BEng Mechanical Engineering programme. The aim of this study was to investigate the students’ response and perception to such a learning environment. A survey was administered to investigate students’ views on the application of problem-based learning in the course. The survey proves that the students responded well to the new approach en-joying activity (72%), trying hard (94%) feeling positive (68%), considering time spent to be beneficial (90%) and believing in instructor having best interest of the students in mind (74%). The response was also positive to interest generation and motivation towards the topic; 82% and 78% positive responses, respectively. The students were convinced about the learning new knowledge aspect of PBL. The majority declared learning more by gathering information themselves (66%) and especially more details on the topic in comparison to the traditional lecture/tutorial approach (72%).

USAGE OF «GIM» SOFTWARE WHILE TEACHING "TECHNICAL MECHANICS" DISCIPLINE

Technical Mechanics being a complex of fundamental general technical disciplines is the theoretical and scientific basis for the study and development of modern engineering. Using its laws and principles buildings, constructions, machines and equipment can be developed and researched. However, Technical Mechanics is the most difficult discipline to learn. The main difficulties of this course are based not only on the application of the principles of theoretical mechanics to complex mechanisms of different types but also the course stands out with its specific and particular features and also based on previously unknown terminology for students as well as is an introduction to the Mechanics of Machines in general. Difficulties in the acquisition of learning content are also caused by time constraints devoted to the study of this subject in higher technical educational institutions. Consequently, teaching Mechanical Engineering in today's context requires a widespread involvement of computer technologies into educational processes that meets the requirements of intensification of students’ individual study and diversifies forms and means of learning, motivates students and optimizes their learning process. The problem of the research is to identify the possibilities of intensifying the process of teaching Technical Mechanics which is a fundamental discipline for other special courses in Technical Institutes using computer training software GIM. The article justifies the feasibility of using GIM software during Technical Mechanics course by students of engineering and technical higher education institutions. GIM software is used during practical classes to support and supplement theoretical lectures; GIM functions as an educational supplementary tool to enhance students' knowledge. Training of first and second year students of general engineering disciplines based on GIM computer training program enhances the professional culture of the future specialist, stimulating his need for continuous self-improvement. New educational technologies are an effective method of teaching students and help better understanding of the subject, promotion and spreading of scientific knowledge

LA MECCANICA DELLE MACCHINE NELL’INNOVAZIONE DEI PRODOTTI E DEI PROCESSI

The present report highlights the current and future role of techniques and methodologies of the Mechanics of Machines, both in the design of devices and systems, and in the university training courses. The underlying theme of the presentation lays in the interpretation of the physical phenomenon which oversees the operation of the machines. This is the foundation allowing to define an input-output interaction between the physical quantities operating on the machine. The cause-effect relation offers the possibility to determine a set of analytical relations for the prediction of the operation of the machine and to simulate theoretical and / or numerical trends in time or frequency domain of the significant mechanical quantities. It is evident the magnitude of the physical phenomena that arise in the operation of a machine, resulting in a broad variety of related Mechanics of Machines topics: from the contact between bodies analysis to tribological aspects, from body geometry to kinematics, from the rigid to deformable body dynamics, from the interaction between mechanical bodies to manmachine interaction, from the kinematic and dynamic behavior of a mechanical system to its interface with the actuators, sensing and control, just to name some of them. It should also be considered that the interpretation of the physical phenomenon of organs of machines has to be supported by significant experimental campaigns, specifically reproduced in laboratory, or related to data from real applications in the different application domains. The evolution of Mechanics of Machines proved in the years to be able to respond to these two interacting and converging questions: on the one hand the need to identify analytical relations, possibly not based on sole mappings of data, but rather on representative analytical relations of physical quantities, and on the other hand, the need, even at the university level, to conduct appropriate laboratory test campaigns related to the real field operation of the machine. With reference to the first objective, the need to determine algorithms, typically non-linear, and the consequent simulations setups, has resulted in the passage of the Machine Mechanics from a theoretical subject, to a subject with strong computational valences creating tools for the prediction of the behavior of devices and systems, in relation to their diagnosis and health state. The second objective has required the achievement of competence also in the field of the test rigs, of sensing and measuring / data acquisition systems. The paper deals with the identification and the presentation of the different areas related to Machine Mechanics, exposing in a matrix the enabling technologies on the one hand and the application domains to which they apply in the other hand. The enabling technologies traditionally belong to the topics of kinematics, statics, dynamics (linear and nonlinear), to the interactions with the environment (force fields, interactions with fluids) and between surfaces (lubrication), control, automation and system identification, as well as to the study and identification of vibratory phenomena, vibro-acoustic and tribological ones, mechatronics, fluid-structure interactions, monitoring, diagnostics and prognostics of mechanical systems, fluid automation and robotics, fluidics and microfluidics, to the implementation of pneumatic, hydraulic, electric and non-conventional technologies, to environmentally friendly and renewable energy systems. The application domains relate to the mechanical systems, such as driving and operating machinery, mechanical devices, mechanisms, transmissions and drives, automatic and robotic, vehicles on road, rail, fixed wing and rotorcrafts, transportation and lifting systems, systems for the production of energy, the biomechanical systems. A summary of the ongoing activities in the different research groups of the Italian Universities is then presented, from which you can also highlight the methodology of the studies addressed, strongly aimed at a unifying approach through the use of fundamental methods of theoretical applied and experimental mechanics, with attention to environmental and energy sustainability, and significantly connected on one side with the state of international research, and on the other with the industrial and manufacturing reality of the country. At the end of the paper sectors of Machine Mechanics that in the opinion of the writer need to be investigated further are discussed. Some technological challenges, such as prognostic models applied to servo systems in primary flight controls for aircraft applications, are outlined. The state of the art in that domain highlights the contribution to the innovation of processes and products, challenge that need to go back to the inputoutput interactions at the base-mechanics layer. Without those aspects it is impossible to be able to predict the evolution of degradation in the actuation systems, and to determine the remaining life of a mechanical device.

Using Blended Learning Approach to Deliver Courses in an Engineering Programme

The paper discusses how the use of blended learning approach was adopted to deliver a 3rd year Mechanics of Machines course for Mechanical Engineering students at the University of Botswana. The course delivery involved a mix of both face-to-face and Blackboard technology to create an efficient and effective learning environment. A survey of 101 students was conducted over a period of 3 years for the respondents to evaluate their teaching and learning preferences. The results show that students accepted the blended learning approach because of its benefits. More lecturers are encouraged to use blended learning and teaching approaches to promote active, independent and lifelong learning.

Using Blended Learning Approach to Deliver Courses in An Engineering Programme

The paper discusses how the use of blended learning approach was adopted to deliver a 3rd year Mechanics of Machines course for Mechanical Engineering students at the University of Botswana. The course delivery involved a mix of both face-to-face and Blackboard technology to create an efficient and effective learning environment. A survey of 101 students was conducted over a period of 3 years for the respondents to evaluate their teaching and learning preferences. The results show that students accepted the blended learning approach because of its benefits. More lecturers are encouraged to use blended learning and teaching approaches to promote active, independent and lifelong learning.