MechEngineerNT
Mechanical
- Dec 13, 2013
- 25
Hi All,
I'm currently working on a project that involves measuring pressure of a material being cast. A test cast was designed in which threaded holes were machined in order to accommodate pressure transducers; which act as a part of the cast wall when inserted. I am interested in measuring the pressure on the wall of the cast. However, after the first attempt, the material absoulutely destroyed the pressure transducers, rendering them useless. So for my next design I created an adaptor which has silicone adhesive cast forward of the transducer. This is so the pressure will still be seen by the transducer, however no direct contact will be made between the material and the transducer itself, it will be flowed though the silicon adhesive.
There is a catch to this though... I added some angles to the internal form of the adapter.....so the silicon adhesive would have a mechanical stop. Note the silicon adhesive is a solid when cured (like an oring 24 shore A hardness). Heat is applied during the casting process, and with the thermal expansion of the silicon, I am expecting a 'thermal preload' on the transducer, due to the angles in the adapter.
So my question is.... Should I treat this as a bolt preload problem? I am only interested in the pressure the material I am casting is exerting on the pressure transducer. I.E. if I have an initial reading of 15 Psi (due to thermal preload), should I zero all the data by -15 Psi, or does this only apply when the pressure is below 15 Psi. So for example, if the transducer is reading 45 Psi, but I know there is a 15 Psi Preload, is the surface pressure 45 Psi or 30 Psi?
Thank you for the help,
MechEngNT
I'm currently working on a project that involves measuring pressure of a material being cast. A test cast was designed in which threaded holes were machined in order to accommodate pressure transducers; which act as a part of the cast wall when inserted. I am interested in measuring the pressure on the wall of the cast. However, after the first attempt, the material absoulutely destroyed the pressure transducers, rendering them useless. So for my next design I created an adaptor which has silicone adhesive cast forward of the transducer. This is so the pressure will still be seen by the transducer, however no direct contact will be made between the material and the transducer itself, it will be flowed though the silicon adhesive.
There is a catch to this though... I added some angles to the internal form of the adapter.....so the silicon adhesive would have a mechanical stop. Note the silicon adhesive is a solid when cured (like an oring 24 shore A hardness). Heat is applied during the casting process, and with the thermal expansion of the silicon, I am expecting a 'thermal preload' on the transducer, due to the angles in the adapter.
So my question is.... Should I treat this as a bolt preload problem? I am only interested in the pressure the material I am casting is exerting on the pressure transducer. I.E. if I have an initial reading of 15 Psi (due to thermal preload), should I zero all the data by -15 Psi, or does this only apply when the pressure is below 15 Psi. So for example, if the transducer is reading 45 Psi, but I know there is a 15 Psi Preload, is the surface pressure 45 Psi or 30 Psi?
Thank you for the help,
MechEngNT
