FOLLOWING DIN EN 13906-1,2,3
Order : Dware
Project : HeliSpring
Subproject : Verification compression spring
Project item : Metallfedern
Spring ID : S.198
Calculated by : André Dewispelaere
Organization : Dware
Date : 26/07/2021

Spring wire grade
Nr, Cl, Spring Wire Grade , E, G, rho, Rm1, Rco
125, DM, EN 10270-1 DM , 206000, 81500, 7.85, 1980, 740
Calculated wire properties Symbol Unit Value
Wire diameter d mm 5.000
Minimum value tensile strength Rm N/mm˛ 1460
Modulus of rigidity G N/mm˛ 81500
Modulus of Elasticity E N/mm˛ 206000

Spring Specifications Symbol Unit Value
Outside diameter of spring De mm 39.60
Nominal diameter of wire d mm 5.000
Deviation of diameter of wire Ad mm 0.025
Number of active coils n -- 9.50
Total number of coils nt -- 11.50
Free spring length L0 mm 105.8
Influence factor spring seat ν -- 0.5
End type A ETA -- D squar+grnd
Number of inactive coils nnaA -- 0.00
Type spring end B ETB -- D squar+grnd
Number of inactive coils nnaB -- 0.00
Hand of coiling -- -- right
Coiling -- -- cold
Shot peened -- -- No
Spring load Symbol Unit Value
Calculation on base of -- -- forces
Minor axial spring force F1 N 280.0
Major axial spring force F2 N 620.0
Expected service life Lh h 2000
Loading frequency fF Hz 50.000
Operating temperature of spring θ °C 20
Extern mass in mass-spring-system m kg 0.500
Calculation of geometry Symbol Unit Value
Mean diameter of coil D mm 34.60
Spring index w -- 6.92
Inside diameter of spring Di mm 29.60
Modulus of rigidity in f(th) G(th) N/mm˛ 81500
Spring rate R N/mm 16.181
Sum of minimal coil spaces Sa mm 12.3
Length of active coils free spring Lw mm 90.7
Coil pitch of free spring m0 mm 9.547
Coil space of free spring a0 mm 4.547
Calculation spring diagram Symbol Unit Value
Minor axial deflection s1 mm 17.3
Spring length at deflection s_1 L1 mm 88.5
Minor axial spring force F1 N 280.0
Major axial deflection s2 mm 38.3
Spring length at deflection s_2 L2 mm 67.5
Major axial spring force F2 N 620.0
Stroke sh mm 21.0
Stroke force Fh N 340.0
Maximum permissble deflection sn mm 35.7
Minimum permissible spring length Ln mm 70.1
Maximum permissible force Fn N 577.7
Deflection to solid sc mm 48.0
Length compressed spring to solid Lc mm 57.8
Theoretical spring force to solid Fc N 776.7
Strength calculation Symbol Unit Value
Stress correction factor k -- 1.203
Corrected minor torsional stress τk1 N/mm˛ 238
Corrected major torsional stress τk2 N/mm˛ 526
Permissible static torsion stress τP N/mm˛ 730
Safety factor static tors stress SF -- 1.39
Tors stress at max permiss deflect τn N/mm˛ 407
Permissible static torsion stress τP N/mm˛ 730
Safety factor max permiss deflect SFn -- 1.79
Torsional stress at solid state τc N/mm˛ 548
Permissible tors stress solid stat τcP N/mm˛ 820
Safety factor tors stress solid st SFc -- 1.50
Number of loading cycles Ncy Mcy 360.000
Strength domain -- -- endurance
Permissible endurance stress τeN N/mm˛ 328
Permissible upper torsional stress τkO N/mm˛ 536
Safety factor on upper tors stress SFO -- 1.02
Lower torsion stress τkU N/mm˛ 238
Corrected stroke stress τkh N/mm˛ 288
Permissible stroke torsion stress τkH N/mm˛ 299
Safety fact stroke torsion stress SFH -- 1.04
Calculation of spring mass Symbol Unit Value
Length of developed spring wire lw mm 1254
Mass of spring mw g 193
Calculation of buckling diagram Symbol Unit Value
Influence factor spring seat ν -- 0.5
Slenderness ratio νL0/D -- 1.529
Major deflection/length ratio s2/L0 -- 0.362
Solid deflection/length ratio sc/L0 -- 0.454
Deflection causing buckling sK mm 0.0
Safety factor on buckling SK -- 0.00
Is spring buckling safe -- -- Yes
Spring work Symbol Unit Value
Minor spring work W1 J 2.422
Major spring work W2 J 11.873
Work exchange DW J 9.451
Power exchange DP W 472.550
Calculation natural frequency Symbol Unit Value
Natural frequency spring coils fe Hz 159
Condition f_e > 12 * f_F satisfied -- -- No
Mass in mass-spring system mred kg 0.693
Resonance freq mass-spring system fr Hz 26.9