Multi-operating-condition adaptability enhancement: simulation and experimental study on the roof beam structure of hydraulic support

Introduction The mechanical properties of the hydraulic support top beam are a critical determinant of mine support safety. The ZY14790/15/25D hydraulic support top beam, tailored for one-pass full-seam mining of medium-thick coal seams, is subjected to extreme deep coal mine working conditions including high ground stress, intense rock burst, and large roof deformation, posing severe challenges to its structural reliability. Methods A finite element model of the ZY14790/15/25D top beam was established via ANSYS software to analyze the stress and deformation characteristics under three typical working conditions (symmetric bending, diagonal torsion, and bending-torsion combination), and the structural weak areas under different conditions were identified. Aiming at the defects of the original top beam design (uneven stress distribution, discontinuous force flow transmission, insufficient local stiffness), an optimization technology focusing on enhancing structural continuity, optimizing rib load-bearing efficiency and strengthening local load-resistant capacity was proposed, with four specific optimization schemes constructed. A new top beam model was then established based on the optimized schemes, and finite element simulation and comparative cyclic loading tests were conducted to verify the optimization effect. Results Finite element simulation results showed that the optimized top beam achieved significant improvements in mechanical performance under all three working conditions: the maximum stress was reduced by 31.44% (symmetric bending), 19.28% (diagonal torsion) and 27.20% (bending-torsion combination), respectively; the maximum deformation was reduced by 12.91%, 12.26% and 15.63%, respectively. Cyclic loading test results indicated that the original top beam suffered fracture at the joint of the top plate and internal stiffening plate after only 16,522 cycles. In contrast, the optimized top beam exhibited a markedly improved fatigue life: although weld cracks appeared and propagated to the base metal at 19,100 cycles, the top beam could stably bear the full yield load after standardized repair, meeting the engineering requirements of actual working conditions. Discussion This study addresses the structural defects of the hydraulic support top beam under complex multi-working conditions through targeted structural optimization, and the proposed optimization technology and schemes are verified to be effective via both numerical simulation and experimental tests. The optimization not only significantly reduces the stress and deformation of the top beam and improves its fatigue life and load-bearing capacity, but also provides a practical and feasible technical scheme for the structural optimization of hydraulic support top beams. Meanwhile, the research results offer important reference value for improving the structural reliability of coal mining equipment and ensuring the safety of deep coal mine production.