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以倾斜板上的块体稳定对象,针对摩擦性材料,对DDA剪切机制开展了研究工作。研究结果表明,即使当接触面摩擦强度略大于临界摩擦角criT?时,在一个边边接触中常会出现锁定与滑动两种不同的状态。在后续计算过程中,由于这种状态会受到阻止,会有不合理的能量产生。这种能量有可能会导致块体难以稳定。DDA可以需要选择适当的接触刚度来控制这种能量的量级,并最终使块体理论临界摩擦角criT?附近稳定。进一步研究表明,出现这一结果主要是由于单独对边边接触上的两个角边接触进行抗剪分析。基于此,提出一种新的改进方法,将边边接触中的两个角边接触进行共剪分析,即将两个角边接触上的剪切力之和与摩擦阻力之和进行分析。测试结果表明,该方法不会受到罚弹簧值和块体弹模的影响。所分析的临界摩擦角与理论值非常接近。
In order to stabilize the object with the block on the inclined plate, the research work on the DDA shear mechanism is carried out for the tribological materials. The results show that, even when the contact surface friction is slightly greater than the critical friction angle criT ?, often occur in one side of the contact lock and slide two different states. In the subsequent calculation process, because of this state will be blocked, there will be irrational energy. This energy may cause the block difficult to stabilize. DDA may need to select the appropriate contact stiffness to control the magnitude of this energy and ultimately stabilize the theoretical critical friction angle near criT ?. Further studies have shown that this result is mainly due to the shear contact analysis of the two edge contacts on the edge contact. Based on this, a new improved method is proposed, in which the two corner edges of the edge contacts are contacted for the total shear analysis, that is, the sum of the shear forces at the two corner edges and the sum of the frictional resistances are analyzed. The test results show that the method is not affected by penalty spring value and block modulus. The critical friction angle analyzed is very close to the theoretical value.