Bolt shear and bearing calculator

Equal direct shear sharing; threads not in shear plane.

fasteners-bolt-shear.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	areamm^2	stressMPa
	28.2743	17.6839
	28.2743	14.1471

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

shear stress budget17.68 MPa✓ passes

BASELINE INPUTS

load2000 Ncount4 diameter6 mm

CALCULATED

area28.274 mm^2

stress17.684 MPa

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Bolt shear and bearing
# Scope: Equal direct shear sharing; threads not in shear plane.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

load = 2000 N
count = 4
diameter = 6 mm

area := pi*diameter^2/4 [mm^2]
stress := load/(count*area) [MPa]

check shear stress budget: stress <= 100 MPa

scenario alternative: load = 1600 N

Calculated from your source · not saved

Baseline · Baseline

shear stress budget17.68 MPa ✓ passes

alternative · alternative

shear stress budget14.15 MPa ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

area: area = pi*diameter^2/4 [mm^2]
stress: stress = load/(count*area) [MPa]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

load: 2000 N
count: 4
diameter: 6 mm

Calculated

area: 28.2743 mm^2
stress: 17.6839 MPa

Assumptions and limits

Equal direct shear sharing; threads not in shear plane.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Bolt shear and bearing. Inputs: transverse load; bolt group; plate thickness. Outputs: bolt shear; plate bearing stress. Model scope: Explicit load paths, preload uncertainty and joint stiffness. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: transverse load, bolt group, plate thickness
Outputs: bolt shear, plate bearing stress
Modes: calculate, compare, sweep
Drawing: Joint load diagram

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS