corrected sign in bond_gran

added beam_tension example

examples/bondspackage/beam_tension.bonds

@@ -0,0 +1,154 @@
+#bond
+
+######## simulation setup #########
+variable dt equal 0.00001
+variable runstep equal 10/${dt}
+variable filestep equal 0.01/${dt}
+##################################
+
+variable rp equal 10*0.0254   #particle radius
+variable d  equal 2*${rp}
+variable sc equal $d-0.000000001
+variable c  equal ${d}+0.1
+variable rb equal 0.8*${rp}
+variable L  equal 200*0.0254+${rp}	    #INCH !
+variable 2L equal 2*$L
+
+atom_style	hybrid granular bond/gran n_bondtypes 1 bonds_per_atom 6
+#atom_style	granular
+atom_modify	map array
+boundary	f f f
+newton		off
+
+#processors  2 1 1
+
+communicate	single vel yes
+
+units		si
+
+region		reg block -$L ${2L} -1 1 -$L 1 units box
+create_box	2 reg #bonds 1 6 			# {num_atom_types} {region} bonds moved into atom_style for LIGGGHTS>=3.X.X
+
+neighbor	1 bin
+neigh_modify	delay 0
+
+#New pair style
+pair_style 	gran model hertz tangential history 
+pair_coeff	* *
+
+#bond
+bond_style 	gran
+
+#for stressbreak
+variable Y  equal 6894.75729*1000*1e4
+
+variable p equal 0.3
+variable G equal 3759.4*6894.75729*1000 #$Y/(2*(1+$p))
+print $Y
+print $G
+
+#double kn = E/lenght; 				 //ZUG - Druck
+#double ks = 12*I*E/(A*lenght*lenght*lenght);    //A*G/lenght; //Schub
+
+variable I equal 0.25*PI*${rb}*${rb}*${rb}*${rb}
+variable A equal PI*${rb}*${rb}
+
+variable kn equal 2*$Y/$d 		 #grain behaivior ?
+variable ks equal 12*$I*$Y/($A*$d*$d*$d) #${kn}/2.5
+
+print $I
+print $A
+print ${kn}
+print ${ks}
+bond_coeff 	1 ${rb} ${kn} ${ks} 1 1e4 1e4
+#bond_coeff 	1 ${rb} $Y $G 1 1e10 1e10 #N rb Sn_bond St_bond TYPE_OF_BOND r_break|sigma_break tau_break (temp)
+
+#Material properties required for new pair styles
+
+fix 		m1 all property/global youngsModulus peratomtype $Y $Y
+fix 		m2 all property/global poissonsRatio peratomtype $p $p
+fix 		m3 all property/global coefficientRestitution peratomtypepair 2 0.2 0.2 0.2 0.2
+fix 		m4 all property/global coefficientFriction peratomtypepair 2 0.3 0.3 0.3 0.3
+
+mass 		1 1.0 #dummy
+mass 		2 1.0 #dummy
+
+# ================================================
+# create just 11 particles in a zylinder
+# ================================================
+region		bc cylinder x 0.00 0.00 ${rp} 0.0 $L units box
+lattice		sc ${sc}
+create_atoms	1 region bc
+run 1
+
+group 		bonded id >= 1
+set		group all density 2700 diameter $d 
+run 1
+
+variable lastone equal atoms
+
+group		freezed id == 1
+group		tipball id == ${lastone}
+
+run 1
+fix f1	freezed freeze	#festlager
+
+fix 		bondcr all bond/create/gran 1 1 1 0.51 1 6 #every itype jtype cutoff btype newperts
+
+timestep	${dt}
+
+#fix		gravi all gravity 9.81 vector 0.0 0.0 -1.0
+
+#atoms may not be lost, insert wall at box bounds
+fix boxwalls_x1 all wall/gran model hertz tangential history primitive type 1 xplane -$L
+fix boxwalls_x2 all wall/gran model hertz tangential history primitive type 1 xplane +${2L}
+fix boxwalls_y1 all wall/gran model hertz tangential history primitive type 1 yplane -1
+fix boxwalls_y2 all wall/gran model hertz tangential history primitive type 1 yplane +1
+fix boxwalls_z1 all wall/gran model hertz tangential history primitive type 1 zplane -$L
+fix boxwalls_z2 all wall/gran model hertz tangential history primitive type 1 zplane +1
+
+#region and insertion
+
+group		nve_group region reg
+
+#apply nve integration to all particles that are inserted as single particles
+fix		integr nve_group nve/sphere
+
+#output settings, include total thermal energyg
+thermo_style	custom step atoms #numbond
+thermo		100
+thermo_modify	lost ignore norm no
+compute_modify	thermo_temp dynamic yes
+
+#insert the first particles so that dump is not empty
+shell rm -rf post
+shell mkdir post
+dump		dmp 	all custom  ${filestep} post/dump*.liggghts id type x y z vx vy vz fx fy fz omegax omegay omegaz radius
+
+#hole koordinaten von letztem partikel
+variable time equal step*dt
+variable px equal x[${lastone}]
+variable py equal y[${lastone}]
+variable pz equal z[${lastone}]
+
+fix outfile all print ${filestep} "${time};${px};${py};${pz}" file beam.csv screen no title "t;x;y;z"
+
+#insert particles
+run		1		#run one step
+fix_modify	bondcr every 0  #do not create new bonds after this line
+variable KIP equal 4448.2216 #N
+variable inch equal 0.0254   #mm
+
+variable M equal 100*${KIP}/${inch}
+variable F equal 10*${KIP}		#N
+#fix 	tipF tipball addforce  0 0 -$F    #1kip=4.4482216kN
+run 10000
+fix 	tipF tipball addforce  $F 0 0    #1kip=4.4482216kN
+#fix 	tipM tipball addtorque 0 $M  0	  #nicht moeglich 
+
+#quit
+variable t equal 1/dt 	#run 1second
+run $t
+
+
+

src/bond_gran.cpp

@@ -318,8 +318,8 @@ void BondGran::compute(int eflag, int vflag)
         double ntorque_mag = vectorMag3D(&bondhistlist[n][6]);
         double ttorque_mag = vectorMag3D(&bondhistlist[n][9]);
 
-        bool nstress = sigman_break[type] < (-nforce_mag/A + 2.*ttorque_mag/J*rb[type]);
-        bool tstress = tau_break[type]    < (-tforce_mag/A +    ntorque_mag/J*rb[type]);
+        bool nstress = sigman_break[type] < (nforce_mag/A + 2.*ttorque_mag/J*rb[type]);
+        bool tstress = tau_break[type]    < (tforce_mag/A +    ntorque_mag/J*rb[type]);
         bool toohot = false;
 
         if(breakmode == BREAKSTYLE_STRESS_TEMP)