Variation of the residual stresses during the fabrication of thick-walled wound glass-reinforced plastic articles

The results of an experimental investigation of the development of the residual stresses in thick-walled glass-reinforced plastic cylinders during the fabrication process are presented. The variation of the stresses from the beginning of winding to removal of the cyclinders from the mandrel is examined.Translated from Mekhanika Polimerov, No. 2, pp. 355–357, March–April, 1974.     

Calculation of the residual stresses and strains in wound reinforced-plastic products

A method is proposed for determining the residual stresses and strains in wound glass-reinforced plastic products. The fabrication process is divided into five stages: winding, heating polymerization, cooling, and removal from the mandrel. The initial stresses that develop during winding and the subsequent stress increment associated with heating are taken into account. Polymerization is treated as a process during which the mechanical and thermophysical properties of the material change. Chemical shrinkage of the resin and its filtration through the fiberglass are disregarded. Equations are derived for the residual radial and peripheral stresses in the finished product, for the residual change in inside diameter, and for the temperature at which the product is released from the mandrel during the cooling process. The experimental data relating to two types of wound products are discussed. The results of a computation of the residual stresses and the residual changes in inside diameter are compared with the experimental data.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, Vol. 5, No. 1, pp. 134–139, January–February, 1969.     

Determination of the residual stresses in wound glass-reinforced plastic rings

The stresses that develop during winding in wound glass-reinforced plastic rings change during polymerization, when the modulus of elasticity in the radial direction is reduced by heating. Further changes occur in connection with cooling and removal from the mandrel. The theoretical relations obtained for determining these stresses are found to be confirmed by experiment.Bauman Moscow Higher Technical College. Translated from Mekhanika Polimerov, No. 5, pp. 892–898, September–October, 1969.     

Effect of climatic loading on the residual stresses and carrying capacity of thick-walled glass-reinforced plastic rings

The effect of climatic loading on the carrying capacity of thick-walled glass-reinforced plastic rings with different residual stress levels has been experimentally investigated. It is established that the rings with the greater residual stress level have a lower maximum breaking load. The carrying capacity of the rings is reduced after simulated aging. This effect is shown to be more sharply expressed in the experiments in which the rings were subjected to dynamic loading.Translated from Mekhanika Polimerov, No. 6, pp. 1132–1134, November–December, 1971.     

Mechanical properties of a carbon-fiber-reinforced plastic and the residual stresses in wound components made out of combined composites

A technique for calculating the residual stresses in wound components made out of mixed carbon-fiber-and glass-fiber-reinforced plastics and the results of the calculations are presented. The effect of the conditions under which the components are wound on the magnitude and nature of the residual stresses distribution in components made out of combined composites is investigated. The results of the calculations are compared with the experimental values.Translated from Mekhanika Polimerov, No. 6, pp. 996–1004, November–December, 1975.     

Calculation of the residual stresses in wound glass-reinforced plastics

The effect of the winding and polymerization conditions on the residual stress distribution in wound glass-reinforced plastic cylinders is subjected to a numerical analysis. The calculations are based on the method proposed in [1]. The computer data are examined and the theoretical and experimental results compared.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1026–1030, November–December, 1970.     

Calculation of the residual stresses in wound glass-reinforced plastic parts when the material characteristics vary over the thickness

The thermoelastic residual stresses in anisotropic rings and cylinders with characteristics that vary over the thickness are determined. The calculation of the stresses in wound glass-reinforced plastic parts is illustrated by examples.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga, Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 686–691, July–August, 1971.     

Experimental determination of residual stresses in wound unidirectional glass-reinforced plastics

The residual stresses in prestressed ring-shaped systems of wound unidirectional glass-reinforced tape have been investigated experimentally. The relation between the residual stress and the winding force has been established. A decrease in the specified prestress is demonstrated. The results of tensile tests on free rings of wound glass-reinforced tape are presented.Mekhanika Polimerov, Vol. 2, No. 1, pp. 123–129, 1966     

Study of the residual (internal) stresses in reinforced epoxy resin

An optical polarization method has been used to study the residual (internal) stresses in reinforced ED-6 epoxy resin cured with maleic anhydride. The effects of "chemical" shrinkage, volume change relaxation during during curing, and the difference linear coefficients of thermal expansion for reinforcement and resin are elucidated. It is shown that adjacent reinforcing elements interact. The stress state is investigated with reference to a model of the elementary cell of the regular structure of a unidirectional glass-reinforced plastic. The residual stresses are found as a function of the resin/reinforcement ratio.Mekhanika Polimerov, Vol. 1, No. 4, pp. 76–80, 1965     

Results of an experimental investigation of the residual stresses in wound glass-reinforced plastics

The results of an experimental investigation of the residual stresses in wound glass-reinforced plastic rings are presented. The residual stresses were determined by the Davidenkov method. The dependence of the maximum tensile and compressive circumferential stresses on ring thickness and polymerization temperature is investigated. The experimental data are compared with the results of calculations based on the theory proposed in [1, 2].Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1116–1119, November–December, 1970.     

Investigation of the residual stresses in the carbamide polymer-glass boundary layer

The residual stresses at the carbamide polymer-glass interface have been investigated for the first time. It has been established that a high residual stress level exists in the polymer-glass boundary layer. Methods of reducing the residual microstress level are indicated.     

Residual stresses in plastic rings reinforced with glass and manufactured with consolidation of the various layers

The residual stresses in thin-wall plastic rings reinforced with glass and prepared by the method of consolidating the layers in combination with various winding regimes have been studied experimentally. It is shown that variation of the winding regime from one layer to another can change the distribution of the stresses through the thickness of the ring.Moscow Energy Institute. Translated from Mekhanika Polimerov, No. 1, pp. 174–176, January–February, 1972.     

A phenomenological method of calculating the residual stresses and plastic deformations in a hollow surface-hardened cylindrical sample

A phenomenological method is proposed for calculating the residual stress and plastic deformation fields in a hollow surface-hardened cylindrical sample. Versions of the hardening are considered that lead to isotropy and anisotropy in the plastic deformations in the surface layer. A hardening anisotropy parameter is introduced that relates the axial and circumferential components of the residual plastic deformation tensor. The experimentally determined axial and/or circumferential components of the residual plastic stress tensor are used as the initial information. The tensor fields of the residual stresses and deformations are constructed assuming the hypothesis of surface hardening anisotropy and the absence of secondary plastic compression deformations and that the tangential components of the residual stress tensor and the plastic incompressibility of the material are small. A technique is developed for identifying the parameters of the proposed method. The adequacy is checked using experimental data for test pieces of type 45 and 12X18H10T steels hardened by hydro-shot blasting treatment and of type 45 steel hardened by treatment with a roller. Good agreement is observed between the calculated and experimental results. It is noted that the anisotropic hardening procedure leads to a substantial difference between the circumferential and axial components of the residual stresses in the hardened layer, unlike the case of isotropic hardening where they are practically identical.