Study on dry friction vibration model based on energy method

Purpose This study aims to establish the friction vibration model. Design/methodology/approach The friction vibration experiment was carried out on a pin disk friction tester. The causes of friction vibration are discussed, and the friction vibration model is established based on the energy method. Findings The experimental and simulation results show that the main cause of friction vibration is the nonlinear change of friction coefficient; degree of the friction vibration has a positive relationship with the friction relative velocity and normal contact positive pressure; the proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration. Originality/value The proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration.

Basic Principles for Thermoplastic Parts Finishing With Impulse Thermal Energy Method

Impulse thermal energy method (ITEM) as modification of the thermal energy method that is successfully used for finishing is considered for application to thermoplastics. The chapter focuses to highlight the basic principles of the thermoplastics treatment by acting heat fluxes inherent to ITEM providing the time-controlled production of combustion species. The properties of thermoplastics and the requirements for their treatment have the greatest impact on processing settings. Thus, the questions of the choice of the preferred fuel mixture, the type of its ignition, and combustion have been studied. By means of numerical situating, the processes of melting and healing of pores during processing are investigated. A method of defining processing settings has been developed, taking into account the limitations on critical temperatures. The promising possibilities of ITEM in relation to the processing of thermoplastics parts obtained by additive technologies are outlined.

Edge and Notch Detection in a Plate Using Time Reversal Process of Leaky Lamb Waves

Leaky Lamb waves are proven effective to carry out nondestructive testing especially on parallel and immersed plates. To detect and localize defects in such a set, this work associates for the first time the topological energy method and leaky Lamb waves. This methodology is applied in a single immersed plate to validate its application. Firstly, Lamb mode A1 is generated in the plate, and the reflected waves on the defect are measured. A first case is examined where the edge is considered as a defect to be localized. Then, measurements are taken on a plate where a notch is machined. The measurements are time reversed and reinjected in a finite-element simulation. The results are then correlated with the direct problem of the topological energy method that is also simulated. In both cases, the defects are precisely localized on the energy images. This work is the preliminary step to an application of the topological energy method to a set of two parallel and immersed plates where the research defect is located in the second plate.

AGROENERGY EFFICIENCY OF IMPROVED TECHNOLOGIES FOR CREATION AND USE OF ALFALFA-CEREAL HAYMAKING IN THE NON-CHERNOZEM ZONE

On the basis of field experience in the creation of alfalfa-grass stands on sod-podzolic soil of the Non-Chernozem zone, a high agroenergetic efficiency of improved technologies has been established, including two zoned varieties of alfalfa changeable (Lugovaya 67 and Pastbishchnaya 88) in combination with agrotechnical methods (change in the composition of leguminous species in the previous period and pre-sowing inoculation of alfalfa seeds with complementary strains of Sinorhizobium meliloti). As a result of the application of the agro-energy method for assessing the production of exchangeable energy and total anthropogenic costs in uniform indicators according to the international SI system (GJ/ha), their payback was established — 8–11 times. This was achieved due to a high share of natural factors (88–91% of total costs), additional nitrogen input into the production process due to increased symbiotic fixation (141–171 kg/ha per year) and long-term use — for 7 years. The productivity of 1 hectare was 62–64 GJ/ha metabolic energy, the collection of protein was 956–1120 kg/ha, the saving of anthropogenic costs due to the exclusion of the use of nitrogen fertilizers was 17–21 GJ/ha.

Phragmén-Lindelöf Alternative Results for a Class of Thermoelastic Plate

The spatial properties of solutions for a class of thermoelastic plate with biharmonic operator were studied. The energy method was used. We constructed an energy expression. A differential inequality which the energy expression was controlled by a second-order differential inequality is deduced. The Phragme´n-Lindelo¨f alternative results of the solutions were obtained by solving the inequality. These results show that the Saint-Venant principle is also valid for the hyperbolic–hyperbolic coupling equations. Our results can been seen as a version of symmetry in inequality for studying the Phragme´n-Lindelo¨f alternative results.

Well-posedness and general energy decay of solutions for a Petrovsky equation with a nonlinear strong dissipation

We consider a nonlinear Petrovsky equation in a bounded domain with a strong dissipation, and prove the existence and the uniqueness of the solution using the energy method combined with the Faedo-Galerkin procedure under certain assumptions. Furthermore, we study the asymptotic behaviour of the solutions using a perturbed energy method.