HELICAL SPRINGS
FOLLOWING DIN EN 13906-1,2,3
Order : Dware
Project : HeliSpring
Subproject : Verification Extension Spring
Project item : Metallfedern
Spring ID : S.202
Calculated by : André Dewispelaere
Organization : Dware
Date : 26/07/2021 




   Spring wire grade




 Nr, Cl, Spring Wire Grade       ,      E,     G,  rho,  Rm1, Rco




421, CR, 1.4310 X10CrNi18-8 HS   , 180000, 70000, 7.90, 2050, 700
Calculated wire properties Symbol Unit Value
Wire diameter d mm 1.600
Minimum value tensile strength Rm N/mm˛ 1910
Modulus of rigidity G N/mm˛ 70000
Modulus of Elasticity E N/mm˛ 180000

Spring Specifications Symbol Unit Value
Outside diameter of spring De mm 12.70
Wire diameter d mm 1.600
Wire diameter deviation Ad mm 0.020
Number of active coils n -- 21.00
Free body length LK mm 35.2
Free spring length between loops L0 mm 50.4
Type spring end A ETA -- german loop
Number inactive coils end A nnaA -- 0.0
Length spring end A LHA mm 7.6
Type spring end B ETB -- german loop
Number inactive coils end B nnaB -- 0.0
Length spring end B LHB mm 7.6
Hand of coiling -- -- right
Coiling -- -- cold
Initial tension applied -- -- Yes
Coiled with -- -- Bench
Shot peening -- -- No
Spring load Symbol Unit Value
To calculate on -- -- forces
Minor axial spring force F1 N 30.0
Major axial spring force F2 N 92.0
Given initial tension force F0 N 11.1
Expected service life time Lh h 1000
Loading frequency fF Hz 0.200
Operating temperature θ °C 20.0
Mass in mass-spring-system m kg 0.350
Calculation of geometry Symbol Unit Value
Modulus of rigidity f(th) G(th) N/mm˛ 70000
Mean diameter of coil D mm 11.1
Spring index w -- 6.94
Inside diameter of spring Di mm 9.5
Spring rate R N/mm 1.997
Attainable initial tension force F0i N 25.4
Initial tension force in diagram F0 N 11.1
Coil pitch at free length m0 mm 1.599
Coil space at free length a0 mm 0.000
Totaal aantal windingen nt -- 21.00
Spring diagram Symbol Unit Value
Minor axial deflection s1 mm 9.5
Minor spring length L1 mm 59.9
Minor axial spring force F1 N 30.0
Major axial deflection s2 mm 40.5
Major spring length L2 mm 90.9
Major axial spring force F2 N 92.0
Maximum permissible deflection sn mm 45.5
Maximum permissible spring length Ln mm 95.9
Maximum permissible spring force Fn N 102.0
Strength calculation Symbol Unit Value
Stress correction factor k -- 1.200
Corrected minor torsional stress τk1 N/mm˛ 248
Corrected major torsional stress τk2 N/mm˛ 762
Permissible static torsion stress τP N/mm˛ 860
Safety fact static torsion stress SF -- 1.13
Tors stress at max permiss deflect τn N/mm˛ 704
Permissible static torsion stress τP N/mm˛ 860
Safety fact at max permiss deflect SFn -- 1.22
Number of loading cycles Ncy Mcy 0.720
Strength domain -- -- limited life
Permissible endurance stress τeN N/mm˛ 560
Permissible upper torsion stress τkO N/mm˛ 767
Safety factor upper torsion stress SFO -- 1.01
Corrected lower torsion stress τkU N/mm˛ 248
Corrected stroke torsional stress τkh N/mm˛ 514
Permissible stroke torsion stress τkH N/mm˛ 519
Safety fact stroke torsion stress SFh -- 1.01
Length of wire and mass Symbol Unit Value
Length of wire spring end A lHA mm 24.1
Length of wire inactive coils A lnaA mm 0.0
Length of wire active coils lK mm 733.1
Length of wire inactive coils B lnaB mm 0.0
Length of wire spring end B lHB mm 24.1
Total length of wire lw mm 781.0
Mass of spring mw g 12.4
Spring work Symbol Unit Value
Minor spring work W1 J 0.090
Major spring work W2 J 1.638
Work exchange DW J 1.548
Power exchange DP W 0.310
Resonance analysis Symbol Unit Value
Natural frequency of coils fe Hz 207
Condition f_e > 12 f_F satisfied -- -- Yes
Mass in mass-spring system mr kg 0.362
Resonance freq mass-spring-system fr Hz 12.0