Self-Heating Mould for Composite Manufacturing

The shipbuilding industry, engine manufacturing, aviation, rocket and space technology are promising fields of application for polymeric composite materials. Shape-generating moulding tools with internal heating are used for the creation of a more economically viable method of moulding of internally heated composite structures. The use of a fine-fibered resistive structure in the heated tools allows implementation of effective heating of the composite and elimination of the need for expensive and energy-intensive heating equipment. The aim of this paper was the reduction of energy consumption for internally heated moulding tools by choosing the optimal parameters for their resistive layer. A method for determination of the parameters of the moulding tool resistive layer was developed. This method allows calculation of the heating layer parameters and implementation of the specified time–temperature regime for moulding of the composite structure. It was shown that energy saving for the heated fiberglass shape-generating moulding tools was from 40 to 60%. It was found that the increase in the thickness of the moulded package of the polymeric composite material resulted not only in a higher supplied power for the heating system, but also in a complication of the method for system control, because of the growing exothermic effect of the binder curing reaction. For composite products based on Hysol EA 9396 binder, thicknesses more than 4 mm are critical, because it is not possible to cope with the self-heating effect only by cooling with ambient air already utilized at the twentieth minute of the moulding process. The influence of the physical and mechanical characteristics of the moulding tool material and stiffening ribs was analysed in terms of energy consumption and controllability of the heating system. Fiberglass shows the lowest energy consumption. Heating of the aluminium and steel moulding tools for the same purpose will require 20% and 45% more power, respectively. An increase in the number of stiffening ribs has a strong effect on the heat removal of the heating system. With a small number of aluminium ribs it is not possible to maintain the specified temperature–time regime for a fiberglass moulded package of 5 mm thick with the use of the equipment. However, when the number of stiffeners is increased to 10, the exothermic effect of the reaction becomes smoother and then the heating equipment can cope with the task. An experimental prototype of heating equipment of moulding tools for the manufacturing of structures of polymeric composite materials, as well as a flexible thermal blanket for repair of non-separable structures, were developed. The results can be the basis for a new method of optimal design of parameters of moulding tool structure at minimal heat removal to the environment.

Extrusion of stiffening ribs on body parts with local heating

A scheme is proposed and analytical expressions are obtained for calculating the kinematics, pressure and damageability of the material during hot extrusion of ribs on body parts. The equations of states during creep, energy equilibrium, kinetics of material discontinuity are used. The calculation results are presented. Keywords: extrusion, local heating, stiffening rib, viscosity, plasticity, stress relaxation, pressure, velocity field [email protected], [email protected]

Production method analysis of stiffening ribs in body components of machines made of polymer composite materials

Analysis of two methods of stiffening rib production as well as two basic materials for their producing in machine components made of polymer composite materials has been carried out. The features, advantage and disadvantages of each of these materials and methods are discussed.

Use of Fine-Grained Heat-Strengthened Steels to Increase the Operation Qualities of Bunker Capacities from Thin-Walled Galvanized Profiles

Purpose. The work is aimed to study the use efficiency of fine-grained heat-strengthened steels (mainly 10G2FB) for steel bunker capacities. At the same time, the structural scheme of such a structure using corrugated steel sheets is considered as the main variant. Methodology. To achieve this purpose, a series of numerical calculations was carried out for a steel bunker capacity of a pyramidal-prismatic type with overall dimensions in plan view of 6×5.2 m and a total height of 4.5 m. The capacity was designed for complicated working conditions, in particular, increased loads, including long-term dynamic ones. The potential possibility of operating the container under conditions of high or low temperatures was also taken into account. At the same time, both the traditional structural scheme of a bunker capacity with horizontal stiffening ribs and the developed structural scheme based on corrugated steel sheets were analyzed. The calculations were carried out by the finite element method based on the SCAD for Windows project complex. Findings. Based on the results of the analysis and comparison of the data obtained in numerical calculations, it was found that the use of fine-grained heat-strengthened high-strength steels (for example, steel 10G2FB) for bunker capacities, both the traditional structural scheme with stiffening ribs and the developed structural scheme based on corrugated sheets, allows reducing material consumption by about 30% in both cases. At the same time, due to the good performance of fine-grained heat-strengthened steel 10G2FB, both at high and at low temperatures, it can be effectively used for steel bunker capacities that work in difficult conditions. Originality. The possibility and efficiency of the use of fine-grained, heat-strengthened high-strength steels for the construction of a steel bunker capacity is estimated. At the same time, such an estimation was given not only for structures of the traditional structural scheme with horizontal stiffening ribs, but also for bunkers with a developed structural scheme based on corrugated sheets. Practical value. From a practical point of view, quantitative parameters of the stress-strain state were obtained during investigations of various design variants for a steel bunker capacity. The data are presented in a compact form that is easy to evaluate and compare. They allow us to state about the improvement of the operation characteristics of capacities and the potential reduction of the risks of their failures and accidents during operation.

Elastic riveted perforated plate with foreign inclusions

The paper focuses on the problem of the elasticity theory for an infinite isotropic elastic plate weakened by circular perforation. The perforated holes are filled with inclusions made of elastic material and sealed along the edges. Transverse stiffening ribs made of another elastic material are riveted to the panel symmetrically to the surface. The elastic perforated plate is subjected to uniform tensile stress (tension at infinity). The action of riveted reinforcing strengthening ribs is modeled by unknown concentrated forces applied to anchor points.

PERFORMANCE STUDY OF SC WALL BASED ON EXPERIMENT AND PARAMETRIC ANALYSIS

Reverse cyclic lateral testing was undertaken to investigate the seismic behavior of 1/4 scale steel-plate concrete (SC) composite walls. The experimental program involved seven SC wall pier specimens. A new chamber structure is proposed, using steel diaphragms to connect the two steel faceplates to each other and to divide the SC wall pier into two parts. Conventional wall specimens failed mainly by tensile fracture of the concrete at the junction of the wall side and wall base, crushing of the concrete at the toe of the wall, or buckling of the steel faceplate. Tearing of the welded joints at the steel faceplates and steel diaphragm, buckling of steel, steel diaphragms being pulled out, tensile fracture and crushing of the concrete were the main failure modes of the chamber structure walls. A parametric numerical analysis in ABAQUS was developed to investigate the effects of the stiffening rib, steel web amount, material strength, shear-span ratio, and axial compression ratio on the seismic response of SC walls. The chamber structure of the SC wall piers can improve the peak load, ductility, and energy-dissipating capacity. The steel faceplate thickness and stiffening ribs can improve the behavior of SC wall piers.