Stressed State in the Vicinity of a Hole in Mechanical Joint of Composite Parts

Dveirin, Oleksandr; Андреев, О. В.; Kondrat’ev, A. V.; Haidachuk, V. Ye.

doi:10.1007/s10778-021-01076-4

Cited by 32 publications

(16 citation statements)

References 13 publications

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“…The main sources of residual stress for PCM structures in the process of moulding are the differences in the thermophysical and elastic properties of the components of the material. Based on the principle of maintaining the integrity of the PCM structure during the process of deformation when moulding on the contact surfaces the layers for displacements (u x , u y , u z ) and tangential stresses (τ xz , τ yz ), the following relations should be fulfilled (Figure 1) [37,38]:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Effect of Heating Conditions during Moulding on Residual Stress–Strain Behaviour of a Composite Panel

et al. 2022

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Currently, we observe extensive use of products made of polymeric composite materials in various industries. These materials are being increasingly used to manufacture large-sized structural parts that bear significant loads. However, increase in the volume of composites used in critical structures is impeded by the instability of properties of the resulting products. In most cases, the reason for this is the residual thermal stress–strain behaviour of the composite structure. This paper deals with the development of a method to predict the residual stress–strain behaviour depending on the heating conditions and distribution of the temperature field over the thickness of the moulded composite package. The method establishes the relationship between moulding process parameters and the effect of the auxiliary and basic equipment on the distribution of the temperature field, stresses, and strains in the moulded product. It is shown that the rate of temperature change at the stage of heating has its effect on the amount of residual deformation of the structure. Experimental studies have been carried out to determine the influence of several factors (rates of heating and cooling) on the residual deflection of the composite panel. Experimental data proves that specimens moulded under conditions of an increased heating rate get a greater deflection than those moulded at a lower heating rate. The error of results during the full-scale experiment did not exceed 6.8%. Our results provide an opportunity to determine the residual thermal stress–strain behaviour of the moulded structure with the required degree of accuracy without a series of experiments. It allows us to significantly simplify the practical implementation of the developed method and avoid any additional production costs.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Effect of Heating Conditions during Moulding on Residual Stress–Strain Behaviour of a Composite Panel

et al. 2022

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“…It allowed us to reduce the number of finite elements in the computational model of the translucent element, i.e., to reduce the time and to increase the accuracy of calculations with the same size of the finite-element grid as in the model as a whole. Since the error of the finite-element method in determination of components of the stress-strain behaviour of structures is of order 1/n 2 [40,41] (n-order of division into elements on one coordinate), with a full-size translucent-element thickness of 48 mm, the grid size was taken equal to 5 mm. For the conical supporting surface, a half-sized grid was used; it allowed us to more accurately model the translucent element's interaction with the metal (titanium) body of the porthole.…”

Section: Numerical Implementationmentioning

confidence: 99%

Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

et al. 2022

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Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress–strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress–strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress–strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress–strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.

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“…That is, the binder is not removed from the moulded material, but it only fills the voids in the PCM. In most cases, this nature of the flow leads to the uneven distribution of the binder in the moulded material, with the observed increase in the binder content in the edge zone [43,44].…”

Section: Introductionmentioning

confidence: 99%

Determination of the Composite Panel Moulding Pressure Value

et al. 2022

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Currently, prefabricated panel structures are typical products made of polymeric composite materials. The integrity of the composite panels, their structure and accuracy of making a contour are largely associated with the manifestation of residual technological stresses. The above phenomena and associated stress-strain behaviour inevitably occur in the process of moulding of the composite products. However, their value, nature, time of occurrence and dynamics of growth can be fully controlled and regulated. The paper deals with the study of the effect of moulding pressure on the quality of a composite product. A dependence is presented that allows us to determine the time for the degassing of the polymeric composite material package at the given temperature and pressure to obtain a monolithic and nonporous structure. It is shown that the peak of the maximum volatile-matter yield for the considered binder types lies in the temperature range where the degree of curing does not exceed 10%; that is, the viscosity values do not prevent the removal of volatile fractions. The effect of moulding pressure on the values of the volume content of the reinforcing material has been studied, and the dependence of the required thickness of the absorbent layer on the parameters of the package of polymer composite material and pressure has been obtained. The dependence of the required thickness of absorbent layer on the parameters of the package of polymeric composite material and pressure has been obtained. The mathematical model developed by us provides an opportunity to predict the stress-strain behaviour of a composite structure at any time during the moulding process. The model is closely related to chemo-viscous and thermal models. It allowed us to synthetize a method for choosing the rational parameters of the moulding process (temperature, pressure, and time), materials of additional layers and equipment. The experiments proved the presence of several defects, such as de-lamination of edges, waviness, swelling and poor adhesion of upper layers in the specimen of the composite panel cooled stepwise in the absence of the vacuum pressure. The surface quality of the specimen of the panel cooled stepwise under vacuum pressure was significantly better, and no visible defects were observed. The obtained theoretical values of deflections, considering the change in physic-mechanical characteristics that depend on the temperature and rheonomic properties of the material, showed an error that did not exceed 7%, compared to the experimental data. Our results can be applied at the enterprises engaged in designing and manufacturing panel structures of polymeric composite materials.

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Stressed State in the Vicinity of a Hole in Mechanical Joint of Composite Parts

Cited by 32 publications

References 13 publications

Effect of Heating Conditions during Moulding on Residual Stress–Strain Behaviour of a Composite Panel

Effect of Heating Conditions during Moulding on Residual Stress–Strain Behaviour of a Composite Panel

Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

Determination of the Composite Panel Moulding Pressure Value

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