Stress-Strain State of Disperse-Hardened Aluminum Joint Tube Under Internal Pressure
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Russian Physics Journal, Vol. 63, No. 5, September, 2020 (Russian Original No. 5, May, 2020)
STRESS-STRAIN STATE OF DISPERSE-HARDENED ALUMINUM JOINT TUBE UNDER INTERNAL PRESSURE O. V. Matvienko,1,2 O. I. Daneyko,1,2 and T. A. Kovalevskaya1,2
UDC 539.37:691.32
The paper presents research into the stress-strain state of an interference-fit connected tube made of dispersehardened aluminum alloy and subjected to the uniform internal pressure. The contact pressure and interference are determined to enhance the elastic resistance limit of the joint tube compared to a one-piece tube. It is shown that with increasing temperature and distance between strengthening particles at the same volume fraction, the maximum allowable interference decreases. In the case of small thickness, the elastic resistance limit of the inner tube increases linearly with the interference growth. The increase in the contact pressure at a comparable thickness of the outer and the inner tubes causes the higher stresses in the outer tube wall and contributes to its plastic deformation. Keywords: disperse-hardened material, aluminum alloys, nanoparticle, plastic deformation, mathematical model, joint tube.
INTRODUCTION The use of composite materials consisting of high-strength fillers (dispersed phases) and plastic binding agents (matrices) [1, 2] allows to significantly improve the performance characteristics and ensure the required level of reliability and durability of technological devices applied in power engineering, chemical and petroleum industries [3– 5]. Owing to nanoparticles distributed in the matrix of disperse-hardened alloys [6, 7], the latter manifest unique properties alternatively to the conventional alloys [8–10]. Such alloys are characterized by isotropy of mechanical properties, high plasticity and strength [11, 12]. The dispersed particle ensemble of the filler strengthens the material by resistance to the dislocation motion in loading, which makes plastic strain difficult. In accordance with the Orowan theory [13–15], a distribution of strengthening particles in the matrix prevents the dislocation motion, thereby enhancing both the strength and strain properties of the material. Strength properties of disperse-hardened materials are determined by the particle shape, size, and the distance between them [16, 17]. Variation of these parameters and the volume fraction of nanoparticles [10] allow producing materials with various properties. In contemporary energy engineering, tubes under internal pressure are widely used in the capacity of heatexchange devices. In order to determine the reliability of heat-exchange devices, it is necessary to know the stresses and strains in the heat-exchange tube walls induced by the load applied. The exact solution of the problem about elastic strain of the heavy-walled tube walls (Lamé problem) under the uniform internal pressure takes the form [18]:
1
Tomsk State University of Architecture and Building, Tomsk, Russia, e-mail: [email protected]; [email protected]; [email protected]; 2National R
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