Mircea Bogdan Tătaru

This paper begins by analyzing several studies discussing the use of Chladni patterns in various contexts. Specifically, Chladni patterns are used to identify the arrangement of nodes associated with the mechanical vibrations of thin plates. Consequently, the utility of these patterns is linked to the spatial distribution of vibration nodes—relevant to applications such as mounting configurations and the accumulation of granular material on separation systems. The ability to rapidly identify node arrangements based on frequency is highly valuable. This paper aims to analyze the correlation between a Finite Element Method (FEM) simulation model and images obtained through the experimental generation of Chladni patterns in order to improve the parameter identification approach of vibrational devices. To this end, a system based on neural networks is proposed for the identification and correlation of these images. The goal of automated identification by use of neural networks is set in order to eliminate subjective identification by the human eye. A correspondence function is derived to relate the experimental Chladni patterns to the numerical FEM model of the thin plates’ natural vibrations. The present research addresses a subject that is not fully studied in the papers cited, namely, that of matching the parameters of numerical modeling with the experimental analysis and expressing them with a mathematical relation.

In the current context, where sustainability, energy efficiency, and reduction of environmental impact are omnipresent themes, the need and interest for conservation, restoration, and reuse of heritage buildings is a topic of real interest. The city of Oradea, engaged in the last decades on the path of a sustainable urban regeneration, has managed to bring back to life part of the valuable Art Nouveau architectural treasure it inherited from previous generations. This paper presents a part of a much wider research and studies on Art Nouveau buildings in Oradea, in the context of the needs arising from the many problems identified with the start of conservation and restoration works. After an introduction on the link between heritage buildings and sustainability and a review of the current context in Oradea related to this topic, one of the emblematic buildings under renovation, the Ullmann Palace, is presented, as well as the results of some physical-mechanical tests carried out. This is followed by some discussions on the innovative and sustainable character of Art Nouveau buildings and the importance of carrying out high-quality conservation and restoration works that are environmentally friendly, safe, and sustainable.

Vibratory machines are widely used for the separation of granular materials of various densities and characteristics. Vibrations are used in this case to increase the technological speed of separation of these materials. Vibratory machines are limited in functioning to fixed oscillation patterns. Control of the oscillation can offer the possibility of changing the oscillation pattern, adapting it to the type of granular material. This paper proposes a vibratory machine with controllable elastic characteristics and pneumatic actuation. From the perspective of functional generalization of these machines, a parallel mechanism with 3 degrees of mobility, starting from the study of the Stewart platform, was designed. The proposed system has been studied both in terms of structure and kinematics, using instruments of simulation tools available in MATLAB and Simulink 2021. The developed model was validated and optimized using multi-body dynamic software ADAMS 2014, obtaining optimal parameters for one type of granular material.

This paper exposes the initial part of a larger research on the impact of the automotive on human health and the quality of life and environment. After a brief introduction on the need for responsible and sustainable approaches and few questions on the subject, some considerations and statistical data are presented, based on a study of the literature on the impact of road traffic and vehicles noise and vibration on people's comfort and health and their quality of life. The research results show, based on official statistics, the significant harmful impact of noise and vibration from motor vehicles and road transport on people's health and quality of life, especially in urban areas during the day. Also, the significant increase in the number of electric and hybrid vehicles from one year to another, a reality and a necessity nowadays, and the awareness that electric vehicles are not perfectly quiet and comfortable, open new research opportunities and require the development of new standards, materials, tools, equipment and test methods in the field of NVH, in a sustained synergistic approach from all stakeholders, to meet the needs and demands of today's consumers, and to comply with existing regulations and standards on environmental protection and sustainable development.

The paper presents a numerical method of kinematical analysis of the articulated quadrilateral mechanism. Starting from Euler’s relation concerning the distribution of speeds written in projections on the fixed reference system axes, a system of differential equations describing the movement of the mechanism was obtained. This system of differential equations was then solved using numerical integration methods and the variation with respect to time of the position kinematical parameters, of the velocities (the first order kinematical parameters), and of the accelerations (the second order kinematical parameters), was obtained. Matrix writing of the differential equations was used in order to make the differential equations set out in the paper easier to solve using the electronic computer.

The paper presents a numerical method of dynamic analysis of a wheel that moves along an inclined plane under the action of a motor torque. The wheel is regarded as a rigid solid body in plane motion that rolls and in the same time slides along a surface which is inclined relative to the horizontal with a certain angle of known value. Therefore, the wheel may be considered as a solid rigid body having two degrees of freedom. The movement of the wheel takes place under the action of a motor torque, active forces and link forces that are unknown. For this reason, link forces must be removed from the differential equations describing the movement of the wheel. The paper also presents a method of removing the link forces from the differential equations of motion.

The paper presents a numerical method of kinematical analysis of the articulated quadrilateral mechanism, using the principle of virtual mechanical work for establishing the relations of connection between the kinematical parameters describing the movement of its elements.

When the dynamic study of a solid rigid body subjected to links is wanted to be performed, the main difficulty is that the differential equations of motion contain in their structure the constraint forces which are unknown. Therefore it is necessary to remove them from the differential equations that describe the motion of the rigid body. The case of a wheel climbing on an inclined plane has been presented in this paper. It is considered that the wheel is rolling without sliding on an inclined plane.

The kinematical study of mechanisms is a very important matter and therefore it must be done very properly. The slidercrank mechanism is very common in engineering applications. The present paper presents an incremental numerical method used for kinematical study of the aforementioned mechanism. The kinematics of the same mechanism is performed using an analytical method. In order to validate the incremental numerical method, the results obtained by using the two methods are then compared.

The wheel is a very important machine part. It is very often found in the construction of the vehicles. Therefore its dynamics must be studied properly. In the paper is presented the dynamical survey of a wheel which climbs on an inclined plane under the action of an active moment produced by an engine. The case of rolling without sliding was taken under consideration in the paper. The approach of the problem is a numerical one. The differential equations describing the movement of the motor wheel were written in matrix form. The paper also presents a method of removing of the constraint forces from the differential equations of motion.