Initial tension + linear rate
Extension spring force
Inputs
User-entered force holding coils together before extension.
User-entered rate over the declared working range.
User-entered extension in the stated linear range.
Results
Total extension-spring forceF
38
Rate contributionkx
30
Declared spring rateMRR
1.5
N/mmF = Fi + kx
A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.
Nearby: Axial response · Beam deflection & reactions · Elastic stability · Solid-shaft torsion
Method
Formula, when it applies, and when it does not
Calculate extension-spring force from initial tension, rate, and extension.
F = Fi + kx
When
- Linear central travel region
- Initial tension stated
- Static screen only
Don’t
- This applies F = Fi + kx using user-entered rate and initial tension. It excludes hook geometry, pretension manufacture, coil contact, nonlinear travel, travel stops, fatigue, corrosion, material condition, dynamic response, and manufacturer load or life limits.
Shigley's Mechanical Engineering Design