Enter Joint Details
Use consistent design values. Stress in MPa is equal to N/mm².
Example Data Table
| Input or result | Example value |
|---|---|
| Total applied load | 36.00 kN |
| Number of rivets | 6 |
| Rivet diameter | 10.00 mm |
| Plate thickness | 6.00 mm |
| Allowable crushing stress | 250.00 MPa |
| Distribution factor | 115.00 % |
| Safety factor | 1.50 |
| Calculated utilization | 69.0 % |
Formula Used
The calculator uses projected bearing area. It compares one critical rivet against the allowable crushing capacity.
Fcapacity = (Ab × σc) ÷ 1000
Fcritical, design = (P × η ÷ N) × S
Pallowable = (Fcapacity × N) ÷ (η × S)
- Ab is projected bearing area in mm².
- d is rivet diameter in mm.
- t is plate thickness in mm.
- σc is allowable crushing stress in MPa.
- P is total service load in kN.
- η is distribution factor divided by 100.
- N is rivet count and S is safety factor.
How to Use This Calculator
- Enter the service load on the joint.
- Enter the total number of load-sharing rivets.
- Enter the rivet diameter and thinner plate thickness.
- Enter the approved allowable crushing stress.
- Set the distribution factor for the most loaded rivet.
- Set a safety factor that matches your design basis.
- Select calculate and review utilization, reserve, and status.
- Check other joint failure modes before finalizing a design.
Crushing Capacity in Riveted Joints
Understanding Rivet Crushing
Rivet crushing, also called bearing failure, occurs when contact pressure deforms material around a rivet hole. The rivet presses against the plate wall. The plate, rivet, or both can yield. This calculator estimates that pressure force. It helps compare applied load with an allowable bearing capacity. It is useful for lap joints, bracket joints, and simple machine connections. The result is a screening value. A complete joint design must also check shear, tear out, edge distance, fatigue, and installation quality.
Why Bearing Area Matters
Bearing area is the projected contact area between one rivet and the connected plate. For a round rivet, the basic area is diameter multiplied by plate thickness. Diameter and thickness use millimetres. Allowable crushing stress uses megapascals, which equal newtons per square millimetre. Their product gives force in newtons. Dividing by one thousand gives kilonewtons. A larger diameter increases the contact area. A thicker plate also increases it. However, larger rivets need proper hole spacing and enough edge distance.
Inputs That Control the Result
The total applied load is the service load carried by the joint. The calculator divides it among the selected rivets. Real joints rarely share load perfectly. Use the distribution factor to represent the force carried by the most critical rivet. A value of one hundred percent assumes equal sharing. Higher values allow for uneven loading, fit-up effects, or eccentricity. The safety factor raises the design demand. Confirm whether your allowable stress already includes a code safety margin before applying another factor.
Interpreting Capacity and Utilization
The capacity per rivet is compared with the factored force on the critical rivet. Utilization below one hundred percent indicates that crushing capacity exceeds the calculated demand. A value near one hundred percent leaves little allowance for uncertainty. The estimated allowable joint load converts the same comparison into a total service load. The recommended rivet count rounds upward. It is a capacity estimate only. Layout limitations, minimum pitch, corrosion allowance, and code rules can require a different rivet count.
Practical Design Checks
Good input data matters more than decimal precision. Measure the smallest relevant plate thickness. Use the nominal or effective rivet diameter required by your standard. Select material stress from an approved specification. Consider temperature, corrosion, and repeated loading. Check whether washers, sleeves, or mixed materials change the bearing surface. For eccentric joints, calculate the direct load and moment load separately. Then use the highest rivet force. Do not assume a symmetric pattern removes every local peak. Use calibrated tools for critical measurements.
Limitations of a Quick Calculation
Crushing capacity is only one failure mode. A joint can fail in rivet shear, plate net-section tension, block shear, pull-through, or local bending before bearing becomes critical. Thin sheet can deform around a hole even when the simple result looks acceptable. Codes may use different bearing coefficients or limit states. This page does not replace those rules. Treat it as an organized engineering check. Record assumptions, inspect the final layout, and have safety-critical designs reviewed by a qualified engineer.
Frequently Asked Questions
1. What does rivet crushing force mean?
It is the bearing force that can deform material around a rivet hole. The check compares applied contact force with the permitted bearing capacity.
2. Why is bearing area diameter times thickness?
The rivet transfers force against the plate wall. The projected contact surface is approximated by rivet diameter multiplied by the bearing plate thickness.
3. Can stress be entered in MPa?
Yes. One MPa equals one N/mm². This makes the diameter and thickness inputs compatible when both are entered in millimetres.
4. Does allowable stress already include safety?
It depends on your standard. Some allowable stresses already include a safety margin. Avoid applying an additional factor unless it matches your design method.
5. What does the distribution factor represent?
It models uneven sharing between rivets. Use 100 percent for ideal equal sharing. Use a larger value when one rivet may carry more load.
6. Does this calculator check rivet shear?
No. It checks crushing or bearing only. Rivet shear, plate tear out, net-section tension, and block shear require separate checks.
7. Why does the suggested rivet count change?
The estimate rounds upward after considering load, stress, geometry, distribution, and safety factor. Layout rules may still require more rivets.
8. Which plate thickness should I use?
Use the thinner member at the bearing interface. For different materials or thicknesses, calculate each member separately and design for the lower capacity.
9. Is hole diameter the same as rivet diameter?
Not always. Clearance holes can be larger. Use the diameter and bearing rules required by your governing design standard.
10. Can the same method screen bolted joints?
The basic bearing concept is similar. However, bolted connections can have different code factors, hole limits, preload effects, and failure rules.
11. What should I do when utilization exceeds 100 percent?
Increase bearing area, add rivets, reduce load, or select stronger material. Then repeat all relevant joint checks with approved design values.