inter-rivet buckling width
inter-rivet buckling width
(OP)
thread2-110541: Repair Strap Inter-rivet Buckling Calculation
The sugesstion to use 2b (where b is the rivet spacing) for the effective width is an excellent one, but do not use this width with the standard inter-rivet buckling stress found in various sources such as Bruhn. I think the difference is about 18% with Timoshenko being higher.
It should be used with the following expression from Timoshenko Theory of Elastic Stablity for a concentrated point buckling load on a panel. 2b is within 2.7% of a infinitely wide sheet so if your sheet is not continuous an adjustment might need to be made. If e/D=2 I think the expression is ok. If less the stress and effective width and hence load will be less.
Pcr = 4 * pi * D / b ALL FOUR(4) EDGES SIMPLY SUPPORTED
Pcr = 8 * pi * D / b ALL FOUR(4) EDGES SS and fixed in rotation
The supports on the left and tight reall don't matter since they are an infinite distance away from the rivet centerline. The support at the top and bottom represent whether the user thing the edge is SS or fixed. The fixed solution is similar to Fcr = 3E/(L/rho)^2
where pi = 3.14159 etc.
D = E * t^3 / [12 * ( 1 - nu^2)
where E = Ec = Young's moduls in compression
t = thickness
nu = Poisson's ratio
The sugesstion to use 2b (where b is the rivet spacing) for the effective width is an excellent one, but do not use this width with the standard inter-rivet buckling stress found in various sources such as Bruhn. I think the difference is about 18% with Timoshenko being higher.
It should be used with the following expression from Timoshenko Theory of Elastic Stablity for a concentrated point buckling load on a panel. 2b is within 2.7% of a infinitely wide sheet so if your sheet is not continuous an adjustment might need to be made. If e/D=2 I think the expression is ok. If less the stress and effective width and hence load will be less.
Pcr = 4 * pi * D / b ALL FOUR(4) EDGES SIMPLY SUPPORTED
Pcr = 8 * pi * D / b ALL FOUR(4) EDGES SS and fixed in rotation
The supports on the left and tight reall don't matter since they are an infinite distance away from the rivet centerline. The support at the top and bottom represent whether the user thing the edge is SS or fixed. The fixed solution is similar to Fcr = 3E/(L/rho)^2
where pi = 3.14159 etc.
D = E * t^3 / [12 * ( 1 - nu^2)
where E = Ec = Young's moduls in compression
t = thickness
nu = Poisson's ratio





RE: inter-rivet buckling width
The ratio between the two methods is ~3 not 1.18
Only two edges - top and bottom are clamped.
I'mm not to happy with the results.
RE: inter-rivet buckling width
RE: inter-rivet buckling width
Fir must be less than or equal to Fcy
From Bruhn on page C7.10 equation C7.15 for a continuous sheet reads
w1 = 1.7 * t * (Ec/Fir)^0.5
where 1.7 has been substituted for 1.9 (see page C7.11 “experiments”) and Fir has been substituted for Fcy.
The load carried by the skin is given by
Load = w1 * t * Fir
From Bruhn on page C7.11 equation C7.15 reads
w2 = 0.62 * t * (Ec/Fir)^0.5
Make sure that you limit w2 to the actual edge distance (e).
where Fir has been substituted for Fcy.
The load carried by the skin is given by
Load = (w1/2 +w2) * t * Fir