Cellular vibro pneumatic compacted corundum. Part 2. Features of physical and mechanical processes of vibration treatment of alumina-foam polystyrene mixtures

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Local Vibration Reduces Muscle Damage after Prolonged Exercise in Men

Prolonged exercise can lead to muscle damage, with soreness, swelling, and ultimately reduced strength as a consequence. It has been shown that whole-body vibration (WBV) improves recovery by reducing the levels of stress hormones and the activities of creatine kinase (CK) and lactate dehydrogenase (LDH). The aim of the study was to demonstrate the effect of local vibration treatment applied after exercise on the level of selected markers of muscle fiber damage. The study involved 12 untrained men, aged 21.7 ± 1.05 years, with a VO2peak of 46.12 ± 3.67 mL·kg−1·min−1. A maximal intensity test to volitional exhaustion was performed to determine VO2peak and individual exercise loads for prolonged exercise. The subjects were to perform 180 min of physical effort with an intensity of 50 ± 2% VO2peak. After exercise, they underwent a 60 min vibration treatment or placebo therapy using a mattress. Blood samples were taken before, immediately after the recovery procedure, and 24 h after the end of the exercise test. Myoglobin (Mb) levels as well as the activities of CK and LDH were recorded. Immediately after the hour-long recovery procedure (vibration or placebo), the mean concentrations of the determined indices were significantly different from baseline values. In the vibration group, significantly lower values of Mb (p = 0.005), CK (p = 0.030), and LDH (p = 0.005) were seen. Differences were also present 24 h after the end of the exercise test. The results of the vibration group compared to the control group differed in respect to Mb (p = 0.002), CK (p = 0.029), and LDH (p = 0.014). After prolonged physical effort, topical vibration improved post-workout recovery manifested by lower CK and LDH activity and lower Mb concentration compared to a control group.

Properties of Vibro-Abrasive Treatment by Combination the Kinds and Granulometric Characteristics of the Medium

The article presents the features of vibration processing of parts of electronic equipment in granular media. The method of combined processing by mixing granules with cutting and activating properties is considered as one of the ways to increase the intensity of vibration treatment. The increase in intensity is experimentally confirmed on the basis of a multivariate experiment with the construction of a regression model of the process.

INTERACTION OF THE ABRASIVE MEDIUM WITH THE TREATED SURFACE AND THE PROCESS OF METAL REMOVAL DURING VIBRATION TREATMENT IN THE PRESENCE OF A CHEMICALLY ACTIVE SOLUTION

Interaction of working medium granules with the processed surface of the part is considered. It is noted that the processing methods are characterized by the dynamic interaction of the abrasive medium with the processed surface. It is indicated that during vibration treatment there is an impact contact of the abrasive granule with the surface of the part, which leads to the formation of characteristic traces during the formation of the surface relief. The types of impact of abrasive grains of working medium granules on the surface of the processed part are identified. It is indicated that the effect of abrasive grains depends on the geometric parameters of the tops of the grains and the working contour of the granule as a whole. The alternation of the operation of abrasive grains in the connection with the nature of the motion of the granule over the surface of the part is shown. The interaction of surfaces of bodies during vibration treatment is considered. The distinctive features of the vibration treatment method from other analogs are indicated. The conditions for the formation of the surface layer of the part during vibration processing are given. The analysis of the mechanical-physicochemical model of the micro-cutting process in the presence of a chemically active solution is carried out and a comparison of the intensity of technologies for vibration treatment of steel parts is given.

Effect of vibration treatment on increasing the durability of tillage equipment working bodies

This paper reports a study into the durability of tillage equipment working bodies. It has been established that the quality of surface layers during plastic deformation depends on a series of factors. These factors include the degree of hardening, the thickness of the hardened layer, the size and nature of the distribution of residual stresses. The study has shown that the technology to restore working bodies that involves vibration oscillations provides for higher durability. Investigation of deformed samples demonstrates that when exposed to vibration treatment, the microstructure is more fine-grained and even; the hardness of the treated surface of a ploughshare blade increases by 22‒35 %. This contributes to hardening the machined surface. It has been established that the tillage equipment working body wear is a random process, which is predetermined by changes in the structural dimensions and shape of cutting elements. An analysis of the wear distribution density of cutting elements has revealed its compliance with the law of normal distribution. It should be noted that the most influential geometric parameter of a working body affecting the part’s resource is the wear depth. This parameter determines the residual thickness of the ploughshare wall. Data from surface-layer studies at hardening make it possible to note a decrease in the limiting state of the examined parameters. In particular, the wear of a ploughshare tip was 17 % less than the limiting state. The study of durability has shown that the amount of tillage equipment working body wear is 1.28 times less when using vibrational plastic deformation. Accordingly, when restoring ploughshares, in order to increase the working bodies’ resource, it is more expedient to use a method that implies the welding of tires made from steel 45 involving sormite surfacing and vibration treatment