Hi All! I am currently busy working on a new knife gate valve design. I have an actuator with a mass of 200 kg attached at the top of the valve. The bottom plate of the actuator is 28 mm thick and I am going to use this plate directly to fasten the actuator(see attached drawing for plate dimensions).(adsbygoogle = window.adsbygoogle || []).push({});

The fastning bolts will be as specified:

2xM16 Bolts at ∅445 P.C.D and 4xM16 Bolts at ∅160PCD...

Bolt material is Stainless Steel 304 A2-70 with properties: (Note:Please advice if this is correct)

Ultimate Tensile Strength (Stu): 700 MPa

Tensile Yield Strength (Sty): 420 MPa

Ultimate Shear Strength (Ssu): 490 MPa

I would like to determine if the bolts will be sufficient to hold the actuator when the valve is fitted in a horizontal position?

Relevant equations:

Shear Stress:

For circular sections: Ss = (4/3)*(V/A)

Where V = applied force (N) and A = Cross-sectional area of the Bolts (mm^2)

Normal Yield Stresses:

FSy*(M*c/I)/Sty ≤ 100 %.

Where M is moment created by the Centre of Mass of the Actuator working at 300 mm from plate (N.m), c = radius of bolts core (mm) and I = Moment of inertia (mm^4)

Preload Stress:

σ= F/A

where F = Preload force inside bolt caused by specific torque applied to bolts (N)

My calcs:

Preload Stress:

Recommended Bolt torque is 160 N.m

T = 0.2DF ( This is an equations I know works for bolts)

Thus F = 160/(0.2*0.016) = 50 kN

and σ= F/A

gives σ = 50000/(∏*13.5^2)/4 = 349 MPa

Shear stress because of weight:

Ss = (4/3)*(V/A)

with V = 1962/6 = 327 N/bolt

Ss = (4/3)*(327/(∏*13.5^2)/4)

Ss = 3.02 MPa

Now here comes the problem: I am relitavely sure that the C.O.M of the actuator(situated 300mm from the bolts) causes a moment at the bolts, which causes normal bending stress?

Then σ = (M)*(c)/I

then σ = (327*300)*(6.75)/(∏*(13.5)^4/64)

= 406 MPa

But if this is the case the bolts will surely not hold the actuator, but I am confinced that it should!!!! Any verification on this will be much appreciated.

Next thing I should do will be to determine the max von mises stress and compare that to the proof stress of the bolt! Help on this is also needed...

Please check attached drawings for some info! Any replies is welcome!

Thanks

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# Calculating total stress in bolts that holds an actuator?

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