Linear Elastic Bonding Model (LEBM)

The Linear Elastic Bonding contact model (LEBM) consists of elastic bonds, providing a different type of behavior than the Bonding and Bonding V2 models.

The theory presented in the articles Comparative Study of Different Discrete Element Models and Evaluation of Equivalent Micromechanical Parameters by J. Rojek et al. (2012) and Advances in the Development of the Discrete Element Method for Excavation Processes by C.A. Labra (2012) served as the foundation for the model's implementation in EDEM. It is recommended that you refer to the aforementioned paper and thesis for an in-depth description of the model.

The behavior of the LEBM is determined by the contact information for a certain pair of elements, either particle-particle or particle-geometry. The LEBM, like many other EDEM contact models, takes into account both normal and tangential (or shear) force components, with the normal direction always acting perpendicular to the line of centers of the two contacting elements and the tangential direction always acting parallel to this.

The contact force F between a pair of contacting elements is decomposed into both normal and tangential components, Fn and Ft, respectively, as:

F= F n + F t = F n n +  F t MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOraiabg2 da9iaadAeadaWgaaWcbaGaamOBaaqabaGccqGHRaWkcaWGgbWaaSba aSqaaiaadshaaeqaaOGaeyypa0JaamOramaaBaaaleaacaWGUbaabe aakiaad6gacaaMc8Uaey4kaSIaaGPaVlaadAeadaWgaaWcbaGaamiD aaqabaaaaa@466B@

Where n is the unit vector along the line of centers of the two elements.

Calculating the force with active bonds

Consider the constitutive equations when the bonds are present and active, for a given pair of elements (where subscripts 1 and 2 indicate the different elements).

The following are calculated on a per-Time Step basis and adjusted incrementally.

The Young's modulus for element i is calculated by:

E i  = 3 G i (1−2 v i ) MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyramaaBa aaleaacaWGPbaabeaakiaaykW7cqGH9aqpcaaMc8UaaG4maiaadEea daWgaaWcbaGaamyAaaqabaGccaGGOaGaaGymaiabgkHiTiaaikdaca WG2bWaaSbaaSqaaiaadMgaaeqaaOGaaiykaaaa@4488@

Where Gi is the Shear modulus and νi the Poisson’s ratio. A normal spring stiffness term is calculated for the bond associated with each element i as:

K ni = 4 E i r i MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4samaaBa aaleaacaWGUbGaamyAaaqabaGccqGH9aqpcaaMc8UaaGinaiaadwea daWgaaWcbaGaamyAaaqabaGccaWGYbWaaSbaaSqaaiaadMgaaeqaaa aa@402A@

Where ri is the physical radius of element i. A single value for the overall normal stiffness of the bond kn is defined as:

k n   =     K n 1 K n 2 K n 1 + K n 2 MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4AamaaBa aaleaacaWGUbaabeaakiaaykW7cqGH9aqpcaaMc8UaaGPaVpaalaaa baGaam4samaaBaaaleaacaWGUbWaaSbaaWqaaiaaigdaaeqaaaWcbe aakiaadUeadaWgaaWcbaGaamOBamaaBaaameaacaaIYaaabeaaaSqa baaakeaacaWGlbWaaSbaaSqaaiaad6gadaWgaaadbaGaaGymaaqaba aaleqaaOGaey4kaSIaam4samaaBaaaleaacaWGUbWaaSbaaWqaaiaa ikdaaeqaaaWcbeaaaaaaaa@4A4F@
The corresponding tangential stiffness kt is calculated as:
k t =   k n 2 v 1 v 2 v 1 + v 2 MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4AamaaBa aaleaacaWG0baabeaakiabg2da9iaaykW7caaMc8Uaam4AamaaBaaa leaacaWGUbaabeaakmaabmaabaWaaSaaaeaacaaIYaGaamODamaaBa aaleaacaaIXaaabeaakiaadAhadaWgaaWcbaGaaGOmaaqabaaakeaa caWG2bWaaSbaaSqaaiaaigdaaeqaaOGaey4kaSIaamODamaaBaaale aacaaIYaaabeaaaaaakiaawIcacaGLPaaaaaa@4932@

With these bond stiffnesses defined, the associated normal contact force of the bond is defined as:

F n =  k n δ n MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaBa aaleaacaWGUbaabeaakiabg2da9iaaykW7caWGRbWaaSbaaSqaaiaa d6gaaeqaaOGaeqiTdq2aaSbaaSqaaiaad6gaaeqaaaaa@3F57@

Where δn is the normal overlap of the contact.

This normal contact force is then damped as follows:

F n d =  c n v n rel MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaDa aaleaacaWGUbaabaGaamizaaaakiabg2da9iaaykW7caWGJbWaaSba aSqaaiaad6gaaeqaaOGaamODamaaDaaaleaacaWGUbaabaGaamOCai aadwgacaWGSbaaaaaa@4262@

Where vnrel is the magnitude of the normal component of the relative velocity between the two contacting elements and cn is the damping coefficient defined as:

c n  =  2α m * k n MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4yamaaBa aaleaacaWGUbaabeaakiaaykW7cqGH9aqpcaaMc8UaaGPaVlaaikda cqaHXoqydaGcaaqaaiaad2gadaahaaWcbeqaaiaacQcaaaGccaWGRb WaaSbaaSqaaiaad6gaaeqaaaqabaaaaa@43FE@

Where

α=    −lne π 2 + ln 2 e MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdeMaey ypa0JaaGPaVlaaykW7caaMc8+aaSaaaeaacqGHsislciGGSbGaaiOB aiaadwgaaeaadaGcaaqaaiabec8aWnaaCaaaleqabaGaaGOmaaaaki abgUcaRiGacYgacaGGUbWaaWbaaSqabeaacaaIYaaaaOGaamyzaaWc beaaaaaaaa@4874@

e is the coefficient of restitution, m* is the equivalent mass:

m*= m 1 m 2 m 1 + m 2 MathType@MTEF@5@5@+= feaahGart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyBaiaacQ cacqGH9aqpdaWcaaqaaiaad2gadaWgaaWcbaGaaGymaaqabaGccaWG TbWaaSbaaSqaaiaaikdaaeqaaaGcbaGaamyBamaaBaaaleaacaaIXa aabeaakiabgUcaRiaad2gadaWgaaWcbaGaaGOmaaqabaaaaaaa@4113@

and mi is the mass of element i:

The magnitude of the tangential contact force is calculated as:

F t =  k t δ t MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaBa aaleaacaWG0baabeaakiabg2da9iaaykW7caWGRbWaaSbaaSqaaiaa dshaaeqaaOGaeqiTdq2aaSbaaSqaaiaadshaaeqaaaaa@3F69@

Where δt is the tangential overlap of the contact. The tangential contact force component is not damped.

Calculating the force with inactive bonds

Consider the constitutive equations and associated failure criteria for when the bonds break or if they were never created.

The failure criteria for the bonds can be defined as follows:

F n   ≤   R n           ( t e n s i o n     o n l y )   F t   ≤   R t MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaWGgb WaaSbaaSqaaiaad6gaaeqaaOGaaGPaVlabgsMiJkaaykW7caWGsbWa aSbaaSqaaiaad6gacaaMc8oabeaakiaaykW7caaMc8UaaGPaVlaayk W7caGGOaGaamiDaiaadwgacaWGUbGaam4CaiaadMgacaWGVbGaamOB aiaaykW7caaMc8Uaam4Baiaad6gacaWGSbGaamyEaiaacMcaaeaaca aMc8UaamOramaaBaaaleaacaWG0baabeaakiaaykW7cqGHKjYOcaaM c8UaamOuamaaBaaaleaacaWG0baabeaaaaaa@5FA6@

Where Rn and Rt are the normal and Shear strengths (defined by the user). The bond will break under one of the following conditions:

The bond is under tension and the magnitude of the normal component of the contact force exceeds the defined normal strength.

The bond is under either tension or compression and the magnitude of the tangential component of the contact force exceeds the defined shear strength.

When under compression, bonds cannot break because of an excessive normal contact force. This is what gives the model its elastic behavior.

In the absence of any bonds - if they were never formed or previously met one of the failure criteria and broke, the normal contact force is calculated only when the contacting elements are compressed.

In this instance, the normal contact force and associated damping force remain the same as defined previously:

F n d =   c n v n r e l MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaBa aaleaacaWGUbaabeaakmaaCaaaleqabaGaamizaaaakiabg2da9iaa ykW7caWGJbWaaSbaaSqaaiaad6gaaeqaaOGaamODamaaDaaaleaaca WGUbaabaGaamOCaiaadwgacaWGSbaaaaaa@4298@
and the tangential contact force is now calculated by first calculating a trial state: 
F t t r i a l   =     F t p r e v   −   k t v t r e l Δ t MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaDa aaleaacaWG0baabaGaamiDaiaadkhacaWGPbGaamyyaiaadYgaaaGc caaMc8Uaeyypa0JaaGPaVlaaykW7caWGgbWaa0baaSqaaiaadshaae aacaWGWbGaamOCaiaadwgacaWG2baaaOGaaGPaVlabgkHiTiaaykW7 caWGRbWaaSbaaSqaaiaadshaaeqaaOGaamODamaaDaaaleaacaWG0b aabaGaamOCaiaadwgacaWGSbaaaOGaeyiLdqKaamiDaaaa@5597@

and subtracting the friction force as given by the Coulomb Friction law:

ε   =   F n t r i a l   −   μ F n MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTduMaaG PaVlabg2da9iaaykW7daabdaqaaiaadAeadaqhaaWcbaGaamOBaaqa aiaadshacaWGYbGaamyAaiaadggacaWGSbaaaaGccaGLhWUaayjcSd GaaGPaVlabgkHiTiaaykW7cqaH8oqBdaabdaqaaiaadAeadaWgaaWc baGaamOBaaqabaaakiaawEa7caGLiWoaaaa@5053@

Where μ is the Static Coefficient of Friction.

The actual tangential contact force Ft is then calculated as:

F t =                                                     F t t r i a l ,         ε ≤ 0                                       μ F n       F t t r i a l F t t r i a l ,       ε > 0 MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaBa aaleaacaWG0baabeaakiabg2da9iaaykW7caaMc8UaaGPaVlaaykW7 caaMc8UaaGPaVlaaykW7caaMc8+aaiWaaqaabeqaaiaaykW7caaMc8 UaaGPaVlaaykW7caaMc8UaaGPaVlaaykW7caaMc8UaaGPaVlaaykW7 caaMc8UaaGPaVlaaykW7caaMc8UaaGPaVlaaykW7caaMc8UaaGPaVl aadAeadaWgaaWcbaGaamiDaaqabaGcdaahaaWcbeqaaiaadshacaWG YbGaamyAaiaadggacaWGSbaaaOGaaiilaiaaykW7caaMc8UaaGPaVl aaykW7cqaH1oqzcqGHKjYOcaaIWaaabaGaaGPaVlaaykW7caaMc8Ua aGPaVlaaykW7caaMc8UaaGPaVlaaykW7caaMc8UaaGPaVlaaykW7ca aMc8UaaGPaVlaaykW7caaMc8UaaGPaVlaaykW7caaMc8UaaGPaVlab eY7aTnaaemaabaGaamOramaaBaaaleaacaWGUbaabeaaaOGaay5bSl aawIa7aiaaykW7caaMc8UaaGPaVpaalaaabaGaamOramaaBaaaleaa caWG0baabeaakmaaCaaaleqabaGaamiDaiaadkhacaWGPbGaamyyai aadYgaaaaakeaadaabdaqaaiaadAeadaWgaaWcbaGaamiDaaqabaGc daahaaWcbeqaaiaadshacaWGYbGaamyAaiaadggacaWGSbaaaaGcca GLhWUaayjcSdaaaiaacYcacaaMc8UaaGPaVlaaykW7cqaH1oqzcqGH +aGpcaaIWaaaaiaawUhacaGL9baaaaa@B799@

The model yields the following force-displacement behavior:

Note:
  1. After you have selected a list of all possible interactions for Particle to Particle or Particle to Geometry contacts, select the interaction you would like to set up bonds for. 
  2. Specify values for Normal Strength and Shear Strength of the formed bonds.
  3. Once you have specified values for the interaction, click OK and repeat the same steps for other interactions you would like to set up bonds for. 

Post Processing

As with EDEM's Bonding and Bonding V2 models, bond attributes are post-processed by examining the characteristics of the associated contacts rather than using EDEM's heritage bond properties. For bond visualization, it is necessary to see the relevant bonds and apply the appropriate coloring.

After a simulation has run with the Linear Elastic Bonding Model enabled, you can post process the behavior of the model using the following custom properties:

Contact custom properties
  1. customInitialOverlap – Indicates the initial value of the overlap of the elements in contact before the bond is formed.
  2. BondStatus – Indicates the property that determines whether the bond exists or not. A value of 1.0 indicates a successful bond has been formed and is currently active. A value of -1.0 indicates that the bond has been broken. A value of 0.0 indicates a bond was never formed.
  3. customShearForce – Indicates the Shear force acting on the contact.
Particle custom properties
  • customBondsInitial – Indicates the number of bonds that an element has after the initial bond formation time.
  • customBondsDamage – Indicates the metric for the damage to the bonds for a given particle, calculated as:

    1.0 −   c u r r e n t   n u m b e r ​ ​   o f   b o n d s   f o r   t h e   p a r t i c l e c u s t o m B o n d s I n i t i a l MathType@MTEF@5@5@+= feaahyart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGymaiaac6 cacaaIWaGaeyOeI0IaaGPaVpaalaaabaGaam4yaiaadwhacaWGYbGa amOCaiaadwgacaWGUbGaamiDaiaaykW7caWGUbGaamyDaiaad2gaca WGIbGaamyzaiaadkhacaaMb8UaaGzaVlaaykW7caWGVbGaamOzaiaa ykW7caWGIbGaam4Baiaad6gacaWGKbGaam4CaiaaykW7caWGMbGaam 4BaiaadkhacaaMc8UaamiDaiaadIgacaWGLbGaaGPaVlaadchacaWG HbGaamOCaiaadshacaWGPbGaam4yaiaadYgacaWGLbaabaGaam4yai aadwhacaWGZbGaamiDaiaad+gacaWGTbGaamOqaiaad+gacaWGUbGa amizaiaadohacaWGjbGaamOBaiaadMgacaWG0bGaamyAaiaadggaca WGSbaaaaaa@77AC@

    A value of 0.0 indicates all initial bonds are still formed. A value of 1.0 indicates all initial bonds are now broken.
Simulation custom properties
  • customTotalBonds – Indicates the total number of bonds in the simulation at the current Time Step. This will be at its maximum value the Time Step after the bonds are formed and will be decremented as bonds are broken.
  • customBrokenBondsNormal – Indicates the total number of bonds in the simulation that have broken due to excessive normal force.
  • customBrokenBondsShear – Indicates the total number of bonds in the simulation that have broken due to excessive Shear force.