You can determine if a bolt connector in an assembly can safely carry the
applied loads, or if it fails.
The software calculates the bolt strength factor of safety (SF) based on
the combined load ratio a connector withstands and compares it with the user-defined
factor of safety.
| Axial load ratio, Ra |
Ra is the maximum of:
- SF * F / (At * S)
- Pre-load / (At * S)
|
SF
|
Bolt strength factor of safety calculated by
the software. SF is the unknown of the combined load ratio
equation. The software calculates the
factor of safety SF twice: SF1 is calculated based on
the first bulleted value of the axial load ratio Ra and
SF2 based on the second value of Ra.
- If (SF1 * F / (At * S)) >
(Pre-load / (At * S)), then the first value of SF1
is considered for the pass/no pass criterion.
- If (Pre-load / (At * S)) > (SF1
* F / (At * S)), then the second value of SF2 is
considered for the pass/no pass criterion.
|
|
F
|
Axial load calculated by the software
|
|
At
|
Tensile area
|
|
Pre-load
|
Bolt pre-load
|
|
S
|
Strength value of connector's material or
grade (could be yield or ultimate tensile strength based on
application). This is the user-defined value for
Bolt Strength
|
|
| Bending load ratio, Rb |
Rb = SF * D * M / (2 * S * I)
|
SF
|
Bolt strength factor of safety calculated by
the software
|
|
M
|
Bending moment calculated by the
software
|
|
D
|
Nominal shank diameter
|
|
S
|
Strength value of connector's material or
grade (could be yield or ultimate tensile strength based on
application). User-defined value for Bolt
Strength.
|
I =0.25*π*r^4
|
| Shear load ratio, Rs |
Rs = SF * V / (0.5 * At * S)
|
SF
|
Bolt strength factor of safety calculated by
the software
|
|
V
|
Shear load calculated by the software
|
|
At
|
Tensile area
|
|
S
|
Strength value of connector's material or
grade (could be yield or ultimate tensile strength based on
application). User-defined value for Bolt
Strength
|
The factor of 0.5 is applied to the material
yield strength (or ultimate tensile strength) to account for the
material shear strength. The calculation of the shear load ratio is
more accurate when the yield strength of the material is considered.
It is a conservative estimate, when the ultimate tensile strength of
the material is considered.
|
| Combined load ratio |
(Ra + Rb)^2 + Rs ^3 <=1 The solution of the third order equation yields the
unknown bolt strength factor of safety SF. Only the positive roots
or the SF are considered.
|
Pass/ No Pass Safety Check
| Bolt connector pass criterion |
Calculated bolt strength factor of
safety SF > User-defined safety factor |
| Bolt connector no pass criterion |
Calculated bolt strength factor of
safety SF < User-defined safety factor |
The pass/no-pass check for connectors is available for linear and
nonlinear static studies. For nonlinear studies, the software displays the pass/no
pass status of all pin and bolt connectors for each solution step.