Dynamic buckling and fragmentation in brittle rods

We present experiments on the dynamic buckling and fragmentation of slender rods axially impacted by a projectile. By combining the results of Saint-Venant and elastic beam theory, we derive a preferred wavelength lambda for the buckling instability, and experimentally verify the resulting scaling law for a range of materials including teflon, dry pasta, glass, and steel. For brittle materials, buckling leads to the fragmentation of the rod. Measured fragment length distributions show two clear peaks near lambda/2 and lambda/4. The non-monotonic nature of the distributions reflect the influence of the deterministic buckling process on the more random fragmentation processes.Comment: 4 pages, 5 figures, submitted to Physical Review Letter

SIMULATION OF SMART POLE VAULTING

The process of pole vaulting is simulated using a finite element two-dimensional model of the pole and the vaulter. The pole is modelled with 20 beam elements and the vaulter with seven such elements linked together by pin joints. 'Smart' behaviour is ach</p

Modeling Slip in Stress-Laminated Timber Bridges: Comparison of Two Finite-Element-Method Approaches and Test Values

Finite-element (FE) simulations of the deformation behavior of a 5.4-m-long, 8-m-wide, and 0.27-m-thick stress-laminated timber bridge deck were conducted. The simulation results were compared with full-scale test results when using a load resembling an axle load placed near the edge and when cycling the load between a high and low value. Two separate approaches to nonlinear FE modeling were used. The first FE model simulates a frictional slip between the glulam beams with an elastic-plastic material model. The second FE model simulates a frictional slip by modeling each discrete contact surface between each beam in the deck. The results show good agreement between simulation and test results and reveal that the simulation model that models contact surfaces produces slightly better results at the expense of a greater modeling effort and increased computational time. Hysteresis in the load versus deformation curves is clearly visible and was due to significant slip between the glulam beams, which was successfully simulated.</p

Modeling Slip in Stress-Laminated Timber Bridges: Comparison of Two Finite-Element-Method Approaches and Test Values

Finite-element (FE) simulations of the deformation behavior of a 5.4-m-long, 8-m-wide, and 0.27-m-thick stress-laminated timber bridge deck were conducted. The simulation results were compared with full-scale test results when using a load resembling an axle load placed near the edge and when cycling the load between a high and low value. Two separate approaches to nonlinear FE modeling were used. The first FE model simulates a frictional slip between the glulam beams with an elastic-plastic material model. The second FE model simulates a frictional slip by modeling each discrete contact surface between each beam in the deck. The results show good agreement between simulation and test results and reveal that the simulation model that models contact surfaces produces slightly better results at the expense of a greater modeling effort and increased computational time. Hysteresis in the load versus deformation curves is clearly visible and was due to significant slip between the glulam beams, which was successfully simulated

Motion of Chips When Leaving the Cutting Zone during Chipboard Plane Milling

Были установлены математические уравнения и проанализированы следующие закономерности процесса плоского фрезерования древесных материалов: влияние угла наклона режущей кромки на угол выхода стружки, влияние угла наклона режущей кромки на скорость движения стружки вдоль лезвия и скорость на выходе стружки из зоны резания, зависимость угла выхода стружки от коэффициентов трения стружки на поверхности обрабатываемого материала и вдоль поверхности лезвия (коэффициенты трения определялись по результатам экспериментальных измерений), а также влияние частоты вращения мельницы на угол выхода стружки

Motion of Chips When Leaving the Cutting Zone during Chipboard Plane Milling

Были установлены математические уравнения и проанализированы следующие закономерности процесса плоского фрезерования древесных материалов: влияние угла наклона режущей кромки на угол выхода стружки, влияние угла наклона режущей кромки на скорость движения стружки вдоль лезвия и скорость на выходе стружки из зоны резания, зависимость угла выхода стружки от коэффициентов трения стружки на поверхности обрабатываемого материала и вдоль поверхности лезвия (коэффициенты трения определялись по результатам экспериментальных измерений), а также влияние частоты вращения мельницы на угол выхода стружки

Generating 3D Finite Element Models of Boards from Computed Tomography Images

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