Experimental and Numerical Development on Multi-Material Joining Technology for Sandwich-Structured Composite Materials

Creating connection points for sandwich-structured composites without losing technical performance is key to realising optimal lightweight structures. The patented LiteWWeight® technology presents cost-effective connections on sandwich panels in a fraction of a few seconds without predrilling. Ultrasonic equipment is used to insert a thermoplastic fastener into the substrate material and partially melt it into the porous internal structure. This creates a highly interlocked connection (connection strength is above 500 N) suitable for semi-structural applications. This study focused on the simulation and experimental validation of this process, mainly on the interaction between the pin and the substrate material during the joining process. The dynamic thermo-mechanical model showed reasonable agreement with experimental methods such as process data, high-speed camera monitoring or computed tomography and allowed the prediction of the connection quality by evaluation of the degree of interlock. The connection strength prediction by the developed model was validated within several various process setups, resulting in a prediction accuracy between 94–99% depending on the setup.

Effect of Ultrasonic Techniques on Welding Technologies

The article discusses selected physical properties of industrial ultrasonic equipment utilising the magnetostrictive or electrostrictive effect. Particular attention was paid to equipment enabling the ultrasonic welding of various metals and thermoplastics. The research involved the comparison of various designs and operation of technological equipment, taking into account selected energy, control and environmental aspects. Based on reference publications it was possible to determine and categorise general features concerning the application of ultrasonic technologies as well as to indicate factors responsible for the formation of imperfections during the ultrasonic welding process.

Effect of Ultrasonic Frequency on Thickener Performance

Gravity thickening is an important aspect to solve numerous environmental and safety problems that were created by tailings discharging at low solid concentrations. Furthermore, in order to efficiently facilitate the separation of released water and solid sediments, a continuous thickening system with ultrasonic equipment has been used to investigate the thickening performance of copper-mine tailings under different ultrasonic frequencies (16 kHz, 20 kHz, 22 kHz, 25 kHz, and 28 kHz). After freeze-drying treatment, the underflow samples are imaged using the scanning electron microscope (SEM); then, the structure of floc or aggregates in the SEM images is quantifiably analyzed using the software of Image J. Results show that the underflow concentration increases as the ultrasonic frequency increases and decreases afterwards. A linear logarithmic function can explain the relationship between underflow concentration and run time at a certain ultrasonic. The underflow concentration is maximized at 64.47 wt. % when the ultrasonic frequency is 22 kHz. Based on the analysis on the microstructure of underflow samples, the minimum pore average size and pore average fraction are obtained when the ultrasonic frequency is 22 kHz, implying that 22 kHz is the optimum ultrasonic frequency combining the results of the underflow concentration.

EQUIPMENT TO PREVENT THE SPREAD OF CORONAVIRUS SARS-COV-2. RESEARC OF SEPARATION ELEMENTS

The aim of the work is to develop separation elements for photocatalytic and ultrasonic equipment for air purification for infectious safety of buildings from coronavirus SARS-COV-2. The equipment is designed for air volume G = 50… 150 m3 / hour, should reduce the degree of microbial contamination of the air to the required level (capture particles of 0.1 μm) and help reduce the risk of airborne diseases. Project considers solving an important scientific and technical problem of creating and development of photocatalytic and ultrasonic heat and mass transfer separation equipment for air clean from dust and viruses (coronavirus SARS-COV-2). The separation technologies and the devices employing them are able to perform purification from particles with the size exceeding 0.10 μm with the efficiency up to 99 %. Combination of this methods will help to develop photocatalytic and ultrasonic heat and mass transfer separation equipment for air clean from dust, viruses and to prevent coronavirus SARS-COV-2 spread.

Wave intensity, an index of ventriculo-arterial interaction, increases in hypertensive subjects but decreases in normotensive subjects during the cold pressor test

Purpose Cardiovascular reactivity to the cold pressor test (CPT) is considered to be a marker for apparent and potential hypertension. We aimed to elucidate the association between the changes in wave intensity (WI) during CPT and hypertension. Methods We recruited 85 volunteers, 33 of whom were hypertensive and 52 normotensive. Using ultrasonic equipment during CPT, we measured carotid arterial WI, which is defined in terms of blood pressure and velocity in the carotid artery. Results The peak WI (W1) increased during CPT in 70.6% of hypertensive individuals, but decreased in 72.6% of normotensive individuals. The chi-square (χ2) test showed that the association between the direction of change in W1 (increase or decrease) and the blood pressure (hypertensive or normotensive) was very strong (P < 0.0001). Conclusion Direction of change in W1 during CPT is a clear marker to discriminate cardiovascular reactivity that does not vary depending on each investigator’s subjective point of view.

Results of research on the intensification of the process of cleaning potato tubers by ultrasonic action and their subsequent storage

The data on the gross harvest of tubers in the Russian Federation are given: approximately 71% of potatoes are produced by the population, 17.4% by agricultural enterprises and 11.5% by farms. It is noted that in the industrial production of potatoes, negative impacts on the soil are associated with crushing and removal of the fertile soil layer, which arise in the process of extracting root crops by the digging and separating working bodies of the harvesting machines. It is proposed to use ultrasonic action on root crops for cleaning them from soil impurities. It was determined that in order to intensify the process of cleaning tubers by ultrasonic action during harvesting, it is necessary to provide operating and technological parameters (frequency of ultrasound oscillations f1 = 48 kHz, vibration intensity S = 42 W/cm², exposure time t = 90 s) of ultrasonic equipment, which will ensure the completeness purification is not less than 84.7%.The results of comparative studies on the intensification of the cleaning of potato tubers allow us to conclude that, regardless of the mass and type of pollution, the greatest positive effect of ultrasonic exposure is observed when processing tubers, the completeness of cleaning of which is on average 13-20% higher.