Testing Devices
Measuring Clamping Force and Deformation Dynamics
Embedded Files
Mk I
Mk I
MK II
MK II
CAD model of MK I
MK I
MK I
This testing device was constructed around the simple idea that the amount of force needed to clamp a fire hose could be measured by stacking weight on top of the hose. The wood apparatus allowed for the weight to be stack on top and concentrated on the two 1/2 inch wide bars attached between the jaws. The 1/2 wide bars simulate a geometry similar to the jaws of existing hose clamp models.
The top jaw of the MK I is allowed to move freely up and down allowing the force from weights stacked on top to be applied to clamp the hose with little to no friction loss on the two guide bars.
Using MK I to test the amount of force required to clamp a hose, demonstrated by Kyle on the left. The top right picture is the point of contact surface for the hose and then the bottom right picture is a zoomed in picture of the hose being clamped.
A disadvantage of the MK I test clamp model is that it does not offer any mechanical advantage when applying force to the fire hose. The variable pressure test was conducted using the MK I and a linear relation established between internal pressure and clamping force required. This linear model estimated clamping forces upwards of 1400 lbs for a hose with an internal pressure of 300psi. This showed that a mechanical advantage would be required to conduct high pressure tests.
MK II
MK II
With the need for a mechanical advantage in mind the MK II was created using a compact bench-mount lever press. The arbor press chosen has a maximum force of 2000 lbs and provides approximately a 18:1 mechanical advantage when the user applies a force to the very end of the handle. To measure this force a hanging scale is attached and pulled perpendicular to the handle to clamp the hose between the jaws. The output force on the hose is then calculated from the measured force and on the scale using the calculated mechanical advantage.
The red bracket in the image to the left was modeled in Solidworks and 3d printed on a MakerBot Replicator. The bracket allows for the same 1/2 inch wide bar used in the MK I to be securely attached to the piston on the MK II. An identical bar that aligned the top bar was attached to the base.
Another advantage of the MK II is that it allows for a clear view of the fire hose from the side. This allowed for the profile view of the compressed hose shown below. This feature was taken advantage of in the varying deformation test to analyze the dynamics when clamping the hose.
Using MK II to test the amount of force required to clamp a hose.
Page updated
Report abuse