BIZOMAT MAKEOS · Fasteners
Riveted Lap Joint Efficiency
How strong is this riveted joint compared with the solid plate, and how will it fail?
Strength of a riveted lap or butt joint per pitch by plate tearing, rivet shearing and crushing, and the joint efficiency compared with the solid plate.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Rivet pitch (along the seam) | mm | Centre distance between rivets in one row. |
| Rivet hole diameter | mm | Diameter of the drilled or punched hole (the driven rivet fills it). |
| Plate thickness | mm | Thickness of the thinner plate. |
| Rivets per pitch (rows) | rivets | Number of rivets in each pitch length (one per row). |
| Shear planes per rivet | choice | Single shear for lap joints; double shear for butt joints with two cover straps. |
| Allowable tensile stress of plate | MPa | Allowable tensile stress of the plate material. |
| Allowable shear stress of rivet | MPa | Allowable shear stress of the rivet material. |
| Allowable crushing stress | MPa | Allowable crushing (bearing) stress. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Rivet pitch (along the seam)
- What it is
- The centre-to-centre spacing of rivets along the seam in one row. The joint strength is worked out for one pitch length.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 50 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A longer pitch raises the tearing strength and the solid plate strength.
- Get it right
- It must be larger than the hole diameter; measure centre to centre, not the gap between holes.
What this means: Rivet hole diameter
- What it is
- The diameter of the drilled or punched hole. A driven rivet swells to fill the hole, so this is the diameter that carries shear and bearing.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 16 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the hole diameter, not the rivet shank diameter before driving.
What this means: Plate thickness
- What it is
- The thickness of the thinner plate in the lap joint, which governs tearing and crushing.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Tearing, crushing and solid plate strengths rise in proportion.
- Get it right
- For unequal plates use the thinner one.
What this means: Rivets per pitch (rows)
- What it is
- The number of rivets in one pitch length of the seam, equal to the number of rows when each row has one rivet per pitch.
- Units and format
- Enter a number in rivets: rivets. The form accepts 1 rivets to 10 rivets. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 rivets as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Shearing and crushing strengths rise in proportion.
- Get it right
- Count the rivets that share the load in one pitch length, not all rivets in the joint.
What this means: Shear planes per rivet
- What it is
- How many shear planes cut each rivet: one in a lap joint, two in a butt joint with a cover strap on each side.
- Units and format
- Choose one of 2 options from the list: Single shear (lap joint); Double shear (butt joint with two straps).
- Example
- The form opens with “Single shear (lap joint)” selected as a worked example. Choose the option that matches your case.
- Get it right
- Double shear doubles the rivet shearing strength; it does not change tearing or crushing.
What this means: Allowable tensile stress of plate
- What it is
- The tensile stress the plate material may carry in your design, from your design code or material data.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 100000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 150 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use an allowable stress, not the ultimate tensile strength.
What this means: Allowable shear stress of rivet
- What it is
- The shear stress the rivet material may carry, from your design code or rivet supplier.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 100000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the value for the rivet material, which often differs from the plate.
What this means: Allowable crushing stress
- What it is
- The crushing (bearing) stress allowed between the rivet and the plate around the hole, from your design code.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 100000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the allowable for the weaker of the rivet and plate materials.
Method and formulas
- Tearing between holes: (p − d) t σt.
- Shearing: rows × planes × πd²/4 × τ; crushing: rows × d t σc.
- Efficiency = weakest ÷ (p t σt).
- Example: 16 mm rivets at 50 mm pitch in 10 mm plate give an efficiency of 26.808%, limited by rivet shearing.
Limitations
- Classical strength-of-materials method; modern structural rivet design follows the applicable code.
- Edge distance, plate buckling and fatigue are not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose rivet pitch and diameter for sheet and plate joints
- Compare single and double riveting
- Repair or assess existing riveted structures
Who it is for
- Design engineers
- Maintenance fitters
- Quality inspectors
What you get
- Strength per pitch by tearing, shearing and crushing
- Solid plate strength per pitch
- Joint efficiency and failure mode
Interpreting the result
- Raise efficiency by balancing tearing against shearing: adjust pitch, diameter or add a row.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1720–1735. Topic reference; no source tables or recommended settings are reproduced.
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