Compensatory bellows oscillations as a corrugated shell with liquid inside

The paper deals with a relevant problem of shipbuilding, i.e. calculation of free and forced vibrations of pipeline compensatory bellows. These devices are used to reduce the vibration load caused by ship power machines. When analyzing the vibrations of the compensatory bellows, it is necessary to take into account the liquid contained in the bellows. In this work, the design model of the bellows is represented by a corrugated elastic shell as a material surface with five degrees of freedom. A variant of the classical theory of shells, built on the basis of Lagrangian mechanics, is used. The influence of the liquid is taken into account by two models. First, the liquid is considered to be ideal and incompressible and is considered through the attached mass to the shell. The shell is replaced by a cylindrical surface with a radius in the middle line of the corrugation. To account for the influence of the frequency of bellows oscillations on the attached inertia of the liquid in the calculation we also used the acoustic approximation; and derived a formula for a generalized attached mass of the ideal compressible liquid. The equations of the bellows oscillations under the periodic loading are obtained. The problem has been solved by the finite difference method. The values of natural frequencies of free vibrations are obtained for the compensatory bellows from the corrosion-resistant heat-resistant steel. It is shown that by taking account of the liquid, we significantly change the natural frequencies of the bellows. With high-frequency vibrations it is necessary to take into account the compressibility of the liquid. The problem of the forced vibrations of the bellows caused by a displacement of its end face by the harmonic law is solved. The internal forces and moments are determined, as well as occurring stresses by Mises criterion in the bellows. We found the critical value of the end face displacement at a frequency of 50 Hz, at which the bellows goes into a plastic state.

Transformed Shell Structures Determined by Regular Networks as a Complex Material for Roofing

The article presents a comprehensive extension of the proprietary basic method for shaping innovative systems of corrugated shell roof structures by means of a specific complex material that comprises regular transformable shell units limited by spatial quadrangles. The units are made up of nominally plane folded sheets transformed into shell shapes. The similar shell units are regularly and effectively arranged in the three-dimensional space in an orderly manner with a universal regular reference surface, polyhedral network, and polygonal network. The extended method leads to the increase in the variety of the designed complex shell roof forms and plane-walled elevation forms of buildings. For this purpose, the rules governing the creation of the continuous roof shell structures of many shells arranged in different unconventional visually attractive patterns and their discontinuous regular modifications are sought. To obtain several novel groups of similar unconventional parametric roof forms, single division coefficients and double division coefficients are used. The easy and intuitive modifications of the positions of the vertices belonging to the polygonal network on the side edges of the polyhedral network accomplished by means of a parametric algorithm allow one to adjust the geometry of the complete shell units to the geometric and material constraints related to the orthotropic properties of the transformed sheeting by means of these coefficients. The innovative approach to the shaping of the diverse unconventional roof structures requires the solving of many interdisciplinary problems in the field of mathematics, civil engineering, construction, morphology, architecture, mechanics, computer visualization, and programming.

Restoration of the Bearing Capacity of Damaged Transport Constructions Made of Corrugated Metal Structures

The paper deals with damages of transport constructions made of corrugated metal structures in the body of a railway track or a road during their operation. A constructive variant to restore the bearing capacity of structures was developed, which consists of installing an annular stiffening rib into the concave part of the corrugated metal profile. The main advantage of this method compared to the double corrugating method is the possibility of performing the reinforcement works during structure operation without interrupting the movement of transport vesicles. The study has proved that the reinforcement method significantly increases the carrying capacity of corrugated metal structures. A numerical finite element model was developed to determine the stress-strain state of structures made of corrugated metal structures reinforced with round stiffening ribs. The soil pressure on the corrugated shell in the model is taken into account with the application of radial and axial forces on the outer surface of the shell. It was determined that the most appropriate location of the ribs is in the centre of the building, where the reinforcement area corresponds to the width of the road or railway line. The advantage of this approach is the ability to more efficiently distribute the reinforcement material by selecting the ribs in the most loaded sections of corrugated metal structures.

Symmetric Free Form Building Structures Arranged Regularly on Smooth Surfaces with Polyhedral Nets

The article is an original insight into interdisciplinary challenges of shaping innovative unconventional complex free form buildings roofed with multi-segment shell structures arranged with using novel parametric regular networks. The roof structures are made up of nominally plane thin-walled folded steel sheets transformed elastically and rationally into spatial shapes. A method is presented for creating such symmetric structures based on the regular spatial polyhedral networks created as a result of a composition of many complete reference tetrahedrons by their common flat sides and straight side edges arranged regularly and symmetrically in the three-dimensional Euclidean space. The use of the regularity and symmetry in the process of shaping different forms of (a) single tetrahedral meshes and whole consistent polyhedral structures, (b) individual plane walls and complex elevations, (c) single transformed folds, entire corrugated shell roofs, and their structures allow a creative search for attractive rational parametric solutions using a few author’s parametric algorithms and their implementation as built-in commands of the AutoCAD visual editor or applications of the Rhino/Grasshopper program.

Crashworthiness Design for Trapezoid Origami Crash Structure Numerical

Corrugations can be considered to be one of the ways to improve the mechanical properties of thin-walled structure in terms of manipulation of surface area. However, this theory requires further validation through experimentation of different materials. Although many research works have been done towards the corrugated shell structures, the flexibility of corrugated sheets of thermoset composite material remains unknown. This study focused on the effects of surface area manipulation by using trapezoid origami structure which is trapezoidal folded lobe shape on the absorbed energy and mechanical properties of Epoxy reinforced with S-type fibreglass. Then the trapezoidal folded lobe shape design was drawn by using AutoCAD which consist of the design of the corrugated composite sheets and the design of trapezoidal folded lobe shape mould. Moreover, the fabrication of the Aluminum mould was done by using a CNC milling machine according to the drawing. So, a compression moulding machine will be used to fabricate the composite structure. Therefore, the vibration and compression tests were carried out to perform a study on the behaviour of the trapezoidal folded lobe thermoset samples and to investigate their deformation behaviour respectively. Based on those tests, the results are shown that the trapezoidal origami samples have higher virtual stiffness than the flat samples, and the trapezoidal origami crash thin wall absorbs 40 % more energy in Y-axis direction compared to in X-axis direction.

Influence of Composition and Spray-Drying Process Parameters on Carrier-Free DPI Properties and Behaviors in the Lung: A review

Although dry powder inhalers (DPIs) have attracted great interest compared to nebulizers and metered-dose inhalers (MDIs), drug deposition in the deep lung is still insufficient to enhance therapeutic activity. Indeed, it is estimated that only 10–15% of the drug reaches the deep lung while 20% of the drug is lost in the oropharyngeal sphere and 65% is not released from the carrier. The potentiality of the powders to disperse in the air during the patient’s inhalation, the aerosolization, should be optimized. To do so, new strategies, in addition to classical lactose-carrier, have emerged. The lung deposition of carrier-free particles, mainly produced by spray drying, is higher due to non-interparticulate forces between the carrier and drug, as well as better powder uniformity and aerosolization. Moreover, the association of two or three active ingredients within the same powder seems easier. This review is focused on a new type of carrier-free particles which are characterized by a sugar-based core encompassed by a corrugated shell layer produced by spray drying. All excipients used to produce such particles are dissected and their physico-chemical properties (Péclet number, glass transition temperature) are put in relation with the lung deposition ability of powders. The importance of spray-drying parameters on powders’ properties and behaviors is also evaluated. Special attention is given to the relation between the morphology (characterized by a corrugated surface) and lung deposition performance. The understanding of the closed relation between particle material composition and spray-drying process parameters, impacting the final powder properties, could help in the development of promising DPI systems suitable for local or systemic drug delivery.

The Optimal Design of a Functionally Graded Corrugated Cylindrical Shell under Axisymmetric Loading

Optimization of parameters of the corrugated shell aims to achieve its minimum weight while keeping maximum stiffness ability. How an introduction of functionally graded corrugations resulted in improved efficiency of this thin-walled structure is demonstrated. The corrugations are graded varying their pitch. The effect of variation in pitch is studied. Homogenization approach gives explicit expressions to calculate the equivalent shell properties. Then well-elaborate methods of optimal design theory are used. The illustrative examples for hydrostatic load demonstrate a high efficiency of the used method.

Calculation of Cylindrical Corrugated Shells Using a Semi-Analytic Finite Element Method

The method of calculating the shells of revolution for an asymmetric load using a semi-analytic finite element method is considered. An example is given of calculating a corrugated cylindrical tank for wind load. Comparison of meridional and annular forces is performed for a smooth and corrugated shell of identical dimensions.