PSI - Issue 40

6

N.A. Makhutov et al. / Procedia Structural Integrity 40 (2022) 264–274 Nikolay A.Makhutov at al. / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 4. Turbopump unit of a liquid-propellant engine (a), its rotor (b), and an impeller of a hydrogen pump TPU with its model for the study of the stress-strain response. Two main experimental methods for physical modeling were developed in Mechanical Engineering Research Institute in cooperation with JSC KBKhA: - testing of models of the impeller of the hydrogen pump of the turbopump unit (TPU) made of optically active materials under centrifugal loading in the air at room temperature; - tests of full-scale impellers at the bench under operational loading (50,000 rpm) in a cryogenic liquid medium. These tests made it possible to obtain initial information about the stress-strain response of the unit according to expression (2). Dangerous critical zones and points were identified when the stress and strain distribution fields were analyzed (Fig. 5). The mathematical modeling in solutions of boundary-value problems was carried out using the theory of stress and strain concentration     max max , , ( , , ) t n n e F K e m    , (4) where K t is the theoretical stress concentration factor, determined experimentally; m is the strain hardening exponent in the power-law approximation of the real stress-strain curve of the material. a b

Fig. 5. Model of the pump impeller and the diagram of sections for determining the stress-strain response (a) and the distribution of the photoelasticity bands in the model (b).