In a vast majority of engines, gas forces from peak cylinder pressure predominate stresses in the connecting rod. However, connecting rods tend to fail on tension, as it is far easier for cracks to form and propagate in tension. Rods that have failed in this way are uncommon now due to...
Im in design so am not sure of the exact method of measurement. I remember using the spark plug type transducers at uni; they were supplied by AVL. I will find out what we use on Monday!
Going back to my original post, I have now finished Uni and am working in powertrain at a high-end OEM.
Peak cylinder pressures are in the region of 120 Bar.
Reading Race Engine Technology this month, Mahle have said peak cylinder pressures for the new F1 engines next season are seeing peak...
The fixed piston is Aluminium, so yes definitely conductive! This is a very good point which I haven't got round to thinking about yet.
There is a check valve (not shown in diagram), through which oil flows into the upper chamber. There is also a discharge valve (pressure relief valve)...
Sorry I should have explained better. The oil is in contact with the underside as shown below.
There is an inner piston and outer piston. The outer piston moves axially relative to the inner, depending on the volume of oil present in the upper chamber. There should be no air present in the...
Hi all,
Just after some advice on whether or not some heat transfer values are realistic.
I have a piston, whose upper and lower crown temperatures are shown below:
Underneath the piston, there is a chamber (not shown), filled with engine oil, which has zero flow rate.
I have calculated...
The plate will attach to the piston by use of countersunk bolts (the number of which is yet to be determined) on the top surface.
Somebody else has recommended Roark, but it appears somebody has hidden it in the library!
Hi everyone,
Just after a bit of advice. The attached images show a circular plate(blue) mounted above a piston (green). There is a force acting over the entire top face.
Obviously the plate shown in blue is going to experience some nasty bending stresses. I'm not 100% sure how to tackle the...
Hi everyone,
As a previous user of NX7.5, I am used to being able to create datum planes and them whichever size I want. I find this easier to see what is going on.
In Catia V5 r19, when I make a reference plane, it does not appear to be possible to alter the size of the plane. I find it is...
Thanks for that Tmoose.
I need to know the oil pressure at the top of the rod. I've dug out some old calculations (from 1954) which provide the following steps:
"The pressure of the oil supply st the piston is the sum of the static supply pressure at the main bearings and the dynamic head due...
Thankyou for the reply.
That would be exceeding the scope of the project I'm working on. Is there a quick method of roughly calculating the change in pressure ? It need not be accurate at this stage; just an approximation would suffice.
Hi everyone,
I need to know the oil pressure rise over the crank, and also through the connecting rod (drilled rod).
Firstly for the crank:
Let's say main bearing oil pressure is 2 bar(g). Engine speed is 1000 RPM (104.7 rad/sec) and the crank drill length is 55mm. Oil specific gravity is...
"Hmm...if there is no pin in the model, then the red bits can't be from pin bending, can they? Sounds like you need to work on your loads and constraints, then come back if a reasonable model still gives troubling results"
Yes this is what concerns and confuses me. I will look into it some...
The force applied in the FEA is a 'radial bearing load' across the top half of the surface area of the bore. I assumed this distributed the load evenly. Does the difference between the FEA and hand calculation arise from the fact it is cylindrical ?
I have worked the projected area out to be 2349.9 mm^2 (bore length = 23mm and Dia = 22mm)
I then divide this by two, as the force will only be acting on one half of the bore, giving me 1174.95 mm^2.
Force / Area = 23200 N / 1174.95 mm^2 = 19.745 N/mm^2 = 19.745 MPa.
Why then does the FEA...
