1 Институт проблем сверхпластичности металлов РАН, ул. Ст. Халтурина, 39, 450001, г.Уфа 2 Уфимский государственный нефтяной технический университет, ул. Космонавтов, 1, 450062, г.Уфа Рассмотрен процесс сверхпластической формовки трехслойной конструкции, состоящей из листа наполнителя, помещенного между двумя листами обшивки, под действием давления инертного газа, подаваемого в технологические зазоры между листами. Основное внимание уделяется учету влияния параметров модели Пэжины на временные характеристики процесса формовки. Предложена математическая модель процесса, основанная на использовании основных гипотез безмоментной теории оболочек. Полученные результаты сопоставлены с результатами решения краевой задачи вязкопластичности, полученными в среде ANSYS. Сделан вывод и применимости предлагаемого упрощенного подхода к анализу основных технологических параметров процесса. Ключевые слова: моделирование; сверхпластическая формовка; трехслойная конструкция; напряженно-деформированное состояние; ANSYS.Superplastic forming of 3-sheet structure consisting of the core sheet placed between two face sheets is considered. Deforming of the 3 sheets structure is effected due to the action of an inertia gas which is supplied between the sheets. Main attention is paid to taking into account the influence of parameters of Perzyna's model on the time characteristics of the process involved. Analytical model of the process under study is based on the main assumptions of the thin shell theory. The results obtained are compared with corresponding finite element solutions of the boundary-value problem in the mechanics of viscoplasticity that are found by means of usage of ANSYS program. The conclusion is made that the analytical approach suggested is suitable in analyzing the time characteristics of the technological process under study.

Superplastic forming of the rectangular edge welded envelope consisting of two rectangular sheets welded along their periphery is considered. The diameter of the cylindrical shell manufactured turns out to be considerably less as compared with the initial width of the rectangular edge welded envelope to be formed superplastically. The deforming of the envelope is effected in a free state, i.e. without fixing the edges of the envelope. Finite element analysis of the stress state is effected by using ANSYS software. Time dependencies of the dome height and width of the envelope are obtained for two cases: plane strain state and plane stress state. The following three stages of the deforming process have been established. Elastic bending of the envelope takes place at the first stage, when the dome height is sharply increasing while the width of the envelope is considerably diminishing. Second stage corresponds to the stationary superplastic flow when the dome height and width of the envelope are changing not so much. The third stage is characterizing by increasing the width of the envelope with the increase in the dome height up to its maximum value. The commercial titanium alloy VT14 (Ti-4,2Al-2,7Mo-1,2V) is used in experiments. The comparison of the analytical predictions with corresponding finite element solutions as well as with experimental data is made.

Venous trophic ulcers take place in the terminal stage of chronic venous insufficiency. The problem of venous trophic disorders is extremely relevant due to the high prevalence among the population. This review considers the comparative characteristics of morbidity data on the example of Germany and the Russian Federation. Particular attention paid to the influence of the course of the disease on patient’s life quality during treatment. The causes of high-cost treatment are reported with approximate calculations for 1 clinical case and total annual costs according to foreign researchers (Australia, Great Britain, USA). The risk factors are discussed in the form of certain concomitant nosologies that significantly aggravate the healing process of ulcers with a brief description of the pathogenesis. The review defines the main goals of the treatment of venous trophic ulcers, as well as separate groups of directions in which it is reasonable to carry out therapeutic measures. Article presents a comparative analysis between the methods of applying compression therapy (elastic bandaging, the use of special stockings) and the influence of the choice on the quality of life of patients. Various methods of topical wound care are described with the obligatory consideration of the stage of the wound process, alternative methods of local treatment are listed (for example, the use of autologous platelet-rich plasma). The efficacy of systemic pharmacotherapy in trophic disorders and the treatment potential of various groups of drugs on the rate of ulcer healing were evaluated. The advantages of using surgical treatment are determined, the main surgical techniques are listed, highlighting the advantages and disadvantages of each. Possible treatment strategies for elderly patients also discussed. The complexity of evaluating the effectiveness of new techniques and an integrated approach to treatment is shown, which in the future will help to correct the direction of finding new ways to solve the problem of venous ulcers in this specific group of patients.