| With the development of science about explosive cutting technology, micro- detonation cord(MDC)that is a mini-linear shaped cumulative cutter are available for use to cut off metals and other brittle materials. A MDC which has the w type linear and fits with flexible dynamite was designed and investigated for the underwater seal equipment composed of polymethyl methacrylate (PMMA).Research the w-type MDC by three methods which is theory, experiment, numerical simulation. To begin with, the section size of 2.5*2.5mm MDC was designed according the booster performance of flexible dynamite. Then, we can verify the MDC cutting capacity through cutting 10mm thick PMMA plate. Second, a jet calculation about sidewalls was given according existing jet quasi-steady theory. Then, we programmed and calculated the crushed speed, crushed angle, jet velocity of different linear locations so that we can analysis that the jet will have what kind of impact by sidewalls. The results show that with the same size of w-type MDC and v-type MDC, the former has a greater speed and penetration ability than latter. Finally, the numerical simulation on w-type MDC cutting of steel plate and PMMA plate is carried out using explicit element code LS-DYNA. Simulation results show that the best standoff distance was greater zero when w-type MDC cut toughness materials. But, the best standoff distance was close to zero when w-type MDC cut brittle materials. In addition, three algorithms which is adaptive, multi-materials arbitrary lagrangian-eulerian (ALE) and smooth particle hydrodynamic (SPH) was used in the simulation. We can find that the accuracy of three algorithms was almost the same when it calculated such large deformation problems of nonlinear dynamics about shaped jet penetration. However, SPH algorithm in dealing with this problem is more suitable because it didn't define the contact, didn't occurring mesh distortion, easy track the particle information to get position, velocity and acceleration results ect. |
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