The I-beams for the log support and to attach the ram to were size so they would be 15 times more rigid than a 9 inch log.  

loading orientations


2x16 in. cylinder and 1/3 hp power unit.
The ram and hydraulic power unit were chosen so that the ram would have maximum speed of 0.5 inch/s and the power unit would use less than 5 amps of current.
Loading Design


We chose to go with a modified version of the V-shaped support.  One of the major modifications was the rounding of the inside edge of the support.  This will help to eliminate any possible checking that could occur to the log. The second reason is the reduction in contact stresses.  A third reason is that this design will allow for easy loading and unloading of logs

Force Measurement

We selected the s-shaped load cell for use in our machine it was reasonably priced and has a very low error percentage.  This load cell also fit very well into our direct loading design.  This load cell can be bolted on to the bottom of the hydraulic ram on one side and the log contact plate on the other.  This load cell is rated to 2000 lbs. with 150% overload capacity so it will survive the loading conditions seen on our machine.
load cell

deflection measurements

The ultrasonic system had every feature we were looking in a distance measurement device. The first criterion in selection was accuracy. The ultrasonic transducer provides us with an accuracy of 0.086 mm. This is enough accuracy to give us consistent results in later calculations. Durability was the next most important criteria. We need a product that can take some bumps and continue to be accurate. The Senix ultrasonic transducer comes in a threaded stainless steel casing, giving us toughness as well as the ability to easily mount it wherever we may need it. The other features that this product offered us were simplicity and variability. It comes with software we can easily use.                                                            

Signal voltage measurement

To get data from the load cell and ultrasonic sensor, we used a data acquisition device from National Instruments.

User Interface

The user interface for this apparatus was designed to be easily used by anyone.  The number of inputs is very limited, allowing the user to quickly run and switch between tests.  In the user interface, the inputs required are: log identifier, log diameter, span, final load limit, and the percentage of the load to be used in preloading the log.  Additional inputs are available, if desired, such as the type of wood, the number of tests that the user is planning to run on the log and a space to record any notes about the log.  The outputs of the interface are: deflection, actual load applied and Modulus of Elasticity.