Pins & Clevis (pins)
Purpose
Analyze pins, clevis joints, and shear connections for double or single shear failure modes including pin shear and plate bearing capacity. Used for linkage and lifting lug screening.
Physics & theory
A pin in double shear carries load on two shear planes: for pin area . Single shear has one plane. Bearing stress on clevis plates is per plate thickness in contact.
Governing capacity is the minimum of pin shear strength and plate bearing strength on each side. Bending of pin between clevis ears may add combined stress if gap is large relative to pin diameter — simplified models treat short pins as pure shear.
Connections transfer load through bearing, shear, tension, and friction paths depending on joint configuration. Preload in bolted joints reduces joint separation and can allow friction to carry shear; without adequate preload, bolts carry full shear in bearing against hole walls.
FEM-based bolt analysis resolves member and bolt stiffness for load sharing; VDI 2230 provides a systematic worksheet for high-fidelity preloaded joints including embedding loss and tightening scatter.
Governing equations
Numerical method
Closed-form shear and bearing screening (engine). User selects single or double shear, pin diameter, plate thickness, and material allowables.
Inputs
| Parameter | Description |
|---|---|
| Pin diameter | Pin size |
| Plate thickness(es) | Clevis ear thickness |
| Shear planes | Single or double |
| Applied force | Joint load |
| Allowables | Pin shear, plate bearing |
Outputs
- Pin shear stress, bearing stress, safety factors, governing mode.
Design codes & checks
- Indicative: Pin shear and bearing safety factors
- US: ASME BTH-1 pin connections (lifting context)
Assumptions & limitations
- Pin bending neglected for standard short clevis proportions.
- No wear or fretting on pin bore.
- Static load; fatigue not computed.
- Assumes aligned holes without eccentricity.
References
- Shigley, J. E., & Budynas, R. G. Mechanical Engineering Design, 11th ed.
- ASME BTH-1-2020. Design of Below-the-Hook Lifting Devices.
- MIL-HDBK-5 (MMPDS) — pin and joint allowables (reference).
- Roark, R. J., Young, W. C., & Budynas, R. G. Formulas for Stress and Strain.
- PhyCalcPro verification benchmarks in
src/data/verification/where available for this module. - Beer, F. P., et al. Mechanics of Materials, 8th ed. McGraw-Hill — foundational stress and deformation theory.