ZHENG Jian, LU Fangyun. On impact response of a prestressed metal beam[J]. Explosion And Shock Waves, 2021, 41(3): 031401. doi: 10.11883/bzycj-2020-0328
Citation:
ZHENG Jian, LU Fangyun. On impact response of a prestressed metal beam[J]. Explosion And Shock Waves, 2021, 41(3): 031401. doi: 10.11883/bzycj-2020-0328
ZHENG Jian, LU Fangyun. On impact response of a prestressed metal beam[J]. Explosion And Shock Waves, 2021, 41(3): 031401. doi: 10.11883/bzycj-2020-0328
Citation:
ZHENG Jian, LU Fangyun. On impact response of a prestressed metal beam[J]. Explosion And Shock Waves, 2021, 41(3): 031401. doi: 10.11883/bzycj-2020-0328
During the service time of engineering structure, most structural members are under prestress conditions. In order to clarify the effect mechanism of prestress on the response of metal beams subjected to impulsive loading, the plastic deformations of metal beams under different axial prestress conditions and different impact strength were studied. The prestress conditions were controlled by a self-designed prestress loading device while the impact loadings were realized by the drop-hammer method. Numerical models were also established to simulate the related test conditions. The numerical results are in good agreement with the test results. By comparing the residual deflections of the beams, it is found that the middle-point residual deflection under compressive prestress is larger than that without prestress, and there is no regular rule between the deflection and prestress under the condition of tensile prestress. From the perspective of energy, it is found that the plastic deformation energy of the beam comes from the external dynamic energy and the initial internal energy. The higher the external kinetic energy ratio is, the higher the energy absorption rate of the beam will be. At a lower external kinetic energy ratio, the energy absorption rate of the beam is relatively higher under compressive prestress, and relatively lower under tensile prestress. While at a higher external kinetic energy ratio, the prestress has little effect on the energy absorption rate. Under compressive prestress, the limit moment increases while the length decreases, and the increased plastic deformation energy is distributed in the beam with reduced length, which will inevitably lead to larger residual deflection. Under the tensile prestress, the limit moment decreases while the length increases, and the increased plastic deformation energy is distributed in the beam with the increased length, for which the residual deflection has no obvious rule. This explains to a certain extent the effect mechanism of prestress on the deformation of the metal beam subjected to impact loading.
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Figure 1. Schematic diagram of an axially-prestressed beam subjected to transverse impact load
Figure 2. Principle of prestress loading
Figure 3. Schematic diagram of drop-weight loading
Figure 4. Structure and size of the beam
Figure 5. Final shapes of the beams under different drop-weight heights
Figure 6. Schematic diagram of the simulation model
Figure 7. Change of axial stress at each point of the beam
Figure 8. Changes of displacement and velocity of the drop hammer during it impacting the beam
Figure 9. Deformation characteristics in the beam
Figure 10. Change of the residual deflection at the middle point of the beam with the initial momentum of the drop hammer
Figure 11. Response process of the beam with the compressive prestress of 100 MPa under the impact of the drop hammer with the initial impact velocity of 2 m/s
Figure 12. Residual deflections of the middle points of the beams under different conditions
Figure 13. Energy absorption ratios of the beams at different external kinetic energy ratios
Figure 14. Total absorbed energies and initial energies of the beams with different prestresses
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