Discrete Element Method in LS-DYNA®


At nor­mal scales a gran­u­lar flow is made up of mil­lions of small par­ti­cles (grains of sand, for in­stance) each of which is sub­ject to the laws of sol­id me­chan­ics. Mod­el­ing such an as­sem­bly us­ing tra­di­tion­al FEM is in­tractable. These sys­tems can be made tractable, how­ev­er, with some sim­pli­fy­ing as­sump­tions:

  1. The par­ti­cles are three di­men­sion­al rigid bod­ies. This saves us from cal­cu­lat­ing in­di­vid­ual de­for­ma­tions.
  2. The par­ti­cles have sim­ple shapes (usu­al­ly spheres). This sim­pli­fies con­tact.
  3. Each dis­crete el­e­ment is a pseu­do-par­ti­cle cor­re­spond­ing to large num­bers of par­ti­cles. This re­duces the num­ber of dis­crete el­e­ments.
  4. Bond­ing be­tween par­ti­cles is mod­eled us­ing elas­tic beams at­tached to par­ti­cle cen­ters.

Tak­en to­geth­er these as­sump­tions are called the “Dis­crete El­e­ment Method.” LS-DY­NA im­ple­ments and cou­ples dis­crete el­e­ments to sol­id me­chan­ics el­e­ments. The DEM has been used to mod­el man­u­fac­tur­ing process­es in­volv­ing hop­pers, ex­plo­sions in mines, frac­tures in brit­tle ma­te­ri­als, as well as for cars dri­ving through sand. This class cov­ers LS-DY­NA’s im­ple­men­ta­tion of the DEM. This class cov­ers how to set up, run, and post-process sim­u­la­tions us­ing this method. This class will al­so pro­vide the the­o­ret­i­cal back­ground for this method in­clud­ing a dis­cus­sion of the ad­van­tages and dis­ad­van­tages of this method.


  1. In­tro­duc­tion to the Dis­crete El­e­ment Method
    1. Ex­am­ple of ap­pli­ca­tion of DEM
    2. The­o­ret­i­cal back­ground of the DEM
  2. In­tro­duc­tion to the DES in LS-DY­NA
    1. Main Key­words.
    2. DES pa­ra­me­ters
    3. Gen­er­at­ing DEM Par­ti­cles in LS-Pre­Post®
    4. Post-Pro­cess­ing DEM Mod­els us­ing LS-Pre­Pos
    5. Ap­pli­ca­tion of DES
  3. In­ter­ac­tion be­tween DEM Par­ti­cles and Struc­ture
  4. Gen­er­al Com­ments
    1. Strengths
    2. Weak­ness­es
  5. Cou­pling to Par­ti­cle Blast Method
  6. Bond Mod­els for the sim­u­la­tion of con­tin­ua
  7. Adap­tive analy­sis of sol­id el­e­ments with DEM
  8. Ref­er­ences