Papers by Keyword: Plate

Abstract: Cracks significantly affect the structural integrity and functionality of mechanical components. While most existing studies focus on identifying straight cracks using dynamic response (DR) data, the characterisation of crack paths, especially curved ones, remains limited. This gap is critical, as the path of crack propagation plays a vital role in determining the severity of structural damage, particularly in critical regions of plate structures. The large number of possible crack paths has made systematic research in this area difficult. Therefore, this study proposes a novel methodology for modelling both straight and curved crack paths in plate structures to analyse their DR using the Finite element method (FEM). Straight cracks are represented by coordinate pairs, while curved cracks are defined using second-order polynomial equations. A combination-based approach is employed to generate feasible curved paths within a bounded region, allowing variation in crack shapes, lengths, and geometries. The results demonstrate that the proposed methodology effectively reduces the total number of crack path configurations from 7140, an impractically large set for detailed analysis, to a manageable subset of 288. This reduction facilitates more efficient implementation in both numerical simulations and experimental investigations without compromising the representational diversity of crack path geometries. They also show that the crack path has a greater influence on the dynamic response than crack length, offering a more comprehensive framework for crack path identification and evaluation.

Abstract: In this century, the development of space technologies has substantially increased. As space launchers improve their performance, space agencies have adopted the use of smaller satellites. Modern space platforms have structural requirements that entail the use of an optimized methodology for automating the creation of satellite designs. Parametrization can play a crucial role in this task. The aim of this paper is to parametrize a structural plate used in a microsatellite preliminary structure and analyze its mechanical behavior under the application of static forces. For such parameterization, a step-by-step procedure was developed using CATIA V5 and a Visual Basic Application was created to assist designers in managing the procedure. Once the preliminary designs were obtained, a parameter structural impact comparison was conducted using ANSYS. Finally, four preliminary designs which met the ASAP 5 launcher requirements were selected, and their structural behaviors were compared.

Abstract: Desiccation is the process of extreme drying that results in cracking in materials such as soils. Cracking is a complex process that has the potential to spread and penetrate deeper into the soil, which could lead to instability in earth structures like embankments. A number of desiccation tests were conducted to observe the crack behaviour of manufactured kaolin clay at laboratory scale. All samples were prepared at variation of initial water content and desiccation tests carried out using aluminium desiccation trays. Their crack behaviour was monitored at different thickness and comparison made to the samples tested on different base materials such as ceramic, steel and wood plates. The drying process, crack propagation and pattern were measured and observed daily. A digital image is captured and the crack intensity factor (CIF) calculated manually using a grid system. It was found that a sample of kaolin clay that was 5 mm thick had the highest CIF with rapid propagation and produced non-orthogonal patterns. It also discovered that the thickness of the samples, type of plates utilised and soil state at the start of the test have an impact on the formation and propagation of cracks.

Abstract: The recovery of a fractured femur using the plate and screw internal fixation. The plate internal fixation is made of metal has good mechanical strength, but causes allergic reactions, secondary surgery, stress shielding and high costs. Evaluation of the lack of metal, now developed biodegradable polymers use Polylactide (PLA) and Poly ɛ-caprolactone (PCL). The advantages of PLA and PCL materi-als can control the rate of degradation and increase mechanical strength. Manufac-turing processes of the plate fixation internal using cold isotactic pressing. Inde-pendent variable on the PLA/PCL blends from 90/10, 80/20, 70/30, and 60/40 wt% and tested for FTIR, XRD, SEM, density and porosity. Result from adding PCL make the degree of crystallinity is decreased significantly. The formation of semi-crystalline the with peak width smaller and the crystal size bigger in the 60PLA sample. PLA/PCL blends largely formed bonding and some immiscibility in the form of small flakes and cavities after the addition of PCL content. Large cavities reduce density and increase porosity which can affect mechanical proper-ties. 90PLA sample has high density and low porosity of 1,186 g/cm3 and 4% porosity, respectively.

Abstract: The stability of rectangular thin plates of Shape Memory Alloys during the forward martensitic phase transition induced by uniform cooling under constant stresses was studied. A model of the constitutive equations of Shape Memory Alloys describing phase structural deformation and taking into account thermomechanical coupling and resistance asymmetry was used. It was shown within the limits of this model that the structural deformation during the loss of stability could not occur. Analytical solutions obtained for different statements of the stability problem were compared. For some statements the curves separating the areas of stability and instability in the plane of stresses had concave parts were obtained. It was shown that increase of the plate thickness brought about rising the influence of the phase deformation on the stability loss process.

Abstract: The modes of hot and cold rolling of plates from an alloy of the Al-Mg system alloy, doped with scandium in the range of 0.10-0.12%, are modeled. At the first stage of work, using the DEFORM-3D software package, we simulated the process of hot sheet rolling at the Quarto 2800 mill, in order to obtain a billet for further cold rolling. Analysis of the simulation data showed that with the adopted compression mode, the metal forming and temperature conditions of rolling make it possible to obtain plates up to 45 mm thick, without defects, with rational power loading of the equipment. Further modeling of the regime of cold rolling of plates with a thickness of up to 31.5 mm showed that cold rolling can be carried out in 4 passes, provided that the stress and rolling force do not exceed the permissible values. At the second stage of work, we conducted an experimental verification of the obtained simulation results both in industrial and in laboratory conditions. It was found that the value of the total compression leading to the destruction of the samples, depending on the rolling conditions, should not exceed 21-30%. At this degree of deformation, the rolled metal from the alloy under study has high strength and plastic properties. Subsequent industrial verification of the research results confirmed that this alloy is quite advanced technologically, while it has high deformability, both during hot and cold rolling, which allows us to recommend it for sheet deformed semi-finished products in the manufacture of structural products for various purposes.

Abstract: Developed on the basis of the pilot and industrial work results, a process flow for the production of mono-block plates with 7600x7600x360 mm dimensions from a 290-ton ingot for subsequent 15H2NMFA steel bottom stamping, was carried out. A practical implementation of the developed procedure for the bottom production from mono-block large-sized plates was made. The basic technology for the mono-block plate production was applied in the conditions of Izhorskiye Zavody, OJSC and Atommash, OJSC, this technology provides for a minimum amount of reconstruction of the existing facilities of these enterprises.

Abstract: Considerable thermal stresses arising in thin-walled metallic materials and structures loaded with tensile stresses can lead either to their complete destruction or to the appearance of discontinuity zones in them.

Abstract: Under industrial conditions, it is common to avoid undesirable costly modernization of the existing equipment and increase the production efficiency. That is why as a basis of the solution to the scientific-applied problem, the authors took the idea of the adjustment of temperature-deformation regimes of metal-roll thick plate rolling for building constructions of the certain assignment in the way to initiate heterogeneous origination of ferrite on the polygonal boundaries of austenite as well as to form, before the finish rolling, as much as possible dispersed grain of hypoeutectoid ferrite. It must guarantee the formation of highly-dispersed final ferrite-perlite structure and the high level of strength and plasticity of the thick plate.

Abstract: To stabilize the geometric parameters of the elastic plates during production, the "aging" method is used, which has low performance, and as an alternative to which the method of ultrasonic stabilization is developed. The essence of ultrasonic stabilization is to create the elastic strain applied via the static load in the central part of the plate by the tool, and to communicate ultrasonic vibrations, which lead to the relaxation of residual stresses and stabilization of the geometric parameters of the plate. Analytical expressions are obtained in order to calculate technological parameters of the ultrasound processing. Computer simulation was held on the basis of the theoretical and analytical models, which has allowed to identify and to visualize the dependence of residual stress and plate deformation on the duration and amplitude of ultrasonic vibrations. On the basis of the obtained dependences it was found that the vibrational amplitude should be reduced to reduce the residual strain, however this increases the processing time. Thus, the greater the amplitude of the ultrasonic vibrations is, the more intense the reduction of residual stresses is. Intensive changes of the residual strain and stresses in the first few seconds are characterized by high efficiency of ultrasonic stabilization, which is recommended as a replacement for the aging method.