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LS-DYNA常见问题汇总
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资料来源：网络和自己的总结 yuminhust2005
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目录
1.Consistent system of units 单位制度 ......................................................................................... 2 2.Mass Scaling 质量缩放 ............................................................................................................... 4 3.Long run times 长分析时间 ....................................................................................................... 9 4.Quasi-static 准静态 ................................................................................................................... 11 5.Instability 计算不稳定 .............................................................................................................. 14 6.Negative Volume 负体积 ........................................................................................................... 17 7.Energy balance 能量平衡 ......................................................................................................... 20 8.Hourglass control 沙漏控制 ..................................................................................................... 27 9.Damping 阻尼 ............................................................................................................................ 32 10.ASCII output for MPP via binout ........................................................................................... 37 11.Contact Overview 接触概述 ................................................................................................... 41 12.Contact Soft 1 接触Soft=1 ..................................................................................................... 45 13.LS-DYNA中夹层板(sandwich)的模拟 .................................................................................. 47 14. 怎样进行二次开发.................................................................................................................. 50
1.Consistent system of units 单位制度
相信做仿真分析的人第一个需要明确的就是一致单位系统(Consistent Units)。计算机只认识0&1、只懂得玩数字，它才不管你用的数字的物理意义。而工程师自己负责单位制的统一，否则计算出来的结果没有意义，不幸的是大多数老师在教有限元数值计算时似乎没有提到这一点。见下面LS-DYNA FAQ中的定义： Definition of a consistent system of units (required for LS-DYNA):
1 force unit = 1 mass unit * 1 acceleration unit 1 力单位 ＝ 1 质量单位 × 1 加速度单位 1 acceleration unit = 1 length unit / (1 time unit)^2 1 加速度单位 = 1 长度单位/1 时间单位的平方
The following table provides examples of consistent systems of units.
As points of reference, the mass density and Young‘s Modulus of steel are provided in each system of units. ―GRAVITY‖ is gravitational acceleration.
Velocity LENGTTIMENERGDENSITGRAVITMASS FORCE STRESS YOUNG’s (56.3KMPH E Y Y Y H) kg kg kg kg kg gm gm gm gm ton lbfs2/in slug kgfs2/mm kg m cm cm cm mm cm cm mm mm mm in ft mm mm s s ms us ms s us s ms s s s s s N 1.e-02N 1.e+04N 1.e+10N KN 1.e+07N 1.e-06N N N lbf lbf Pa Joule 7.83E+03 2.07E+11 15.65 9.806 7.83E-03 2.07E+09 1.56E+03 9.81E+02 7.83E-03 2.07E+03 1.56 9.81E-04 7.83E-03 2.07E-03 1.56E-03 9.81E-10 15.65 9.81E-03 GPa KN-mm 7.83E-06 2.07E+02 dyne dy/cm2 erg 7.83E+00 2.07E+12 1.56E+03 9.81E+02 Mbar 1.e7Ncm 7.83E+00 2.07E+00 1.56E-03 9.81E-10 Pa MPa MPa psi psf 7.83E-03 2.07E+11 1.56E+04 9.81E+03 15.65 9.81E-03 386 32.17 N-mm 7.83E-03 2.07E+05 N-mm 7.83E-09 2.07E+05 1.56E+04 9.81E+03 lbf-in 7.33E-04 3.00E+07 6.16E+02 lbf-ft 15.2 4.32E+09 51.33 kgf kgf/mm2 kgf-mm 8.02E-10 7.00E+02 1.56E+04 (Japan) mN 1000Pa 7.83E-06 2.07E+08 9.81E+02 gm cm ms 100000Pa 7.83E+00 2.07E+06