Measuring and testing – Vibration – By mechanical waves
Patent
1991-07-23
1993-07-06
Williams, Hezron E.
Measuring and testing
Vibration
By mechanical waves
73 73, G01N 2918
Patent
active
052243818
DESCRIPTION:
BRIEF SUMMARY
It is known that the mechanical properties of various construction materials which are hygroscopic, in particular wood, are difficult to determine, all the more so because they vary with the moisture content inside these materials.
For wood, classes (3 or 4 depending on the system) have hitherto been established experimentally and wood specialists use visual inspection to assign samples to the class which seems appropriate. This procedure is very approximate and dependent on the specialist. Furthermore, it hardly takes account of the factor of the moisture content and temperature of the material.
The aim of the present invention is to eliminate these disadvantages and to provide an apparatus for automatically and non-destructively determining the class of standardized mechanical properties of a sample of a hygroscopic material, such as wood, from measurements made by the apparatus itself on the sample in question. The invention corresponds to claim 1.
The attached drawing shows, by way of example, an embodiment of the apparatus forming the subject of the invention.
FIG. 1 is a schematic general view of this embodiment.
FIG. 2 is a schematic view in section of one of the two multiple detector heads belonging to this embodiment.
FIG. 3 is a block diagram of the apparatus according to FIG. 1.
FIG. 1 shows a wooden beam 1 for which it is desired to know the class of standardized mechanical properties to which it belongs.
Two heads have been indicated very schematically by 2 and 3; each head is applied to one end of the beam 1 and, as will be seen below, has three probes or detectors for measuring the propagation time of an ultrasonic wave emitted by 2 and received by 3, the moisture content in the beam and the temperature in the beam. These detectors are of known types. 4 is a box which houses electronic devices and which is equipped with a keyboard 5 and a display 6.
FIG. 2 shows the head 2. The body of the head 2 is made of an electrically insulating material. It is equipped on the inside with a sliding element 2a, inside which there is a piezoelectric transducer 11 used either for emitting or for receiving ultrasonic waves. The element 2 is firmly fixed to two metal points 10, 12 which are to be driven into the beam 1, as shown in the drawing, in order to ensure that the element 2 is fixed to one face of the beam 1 when they are driven into this face, for example by hammering the left-hand end of the head 2 in FIG. 2.
A compression spring 9 serves to apply the transducer 11 against the end of the beam. It also serves to protect the transducer from shocks when the points 10, 12 are being driven in.
These points 10, 12 act as probes for measuring the electrical resistance between them with a view to determining the moisture content inside the beam 1.
One of the points, 12, is thermally connected to a thermistor which is located in a cavity in the element 2 and which serves to measure the temperature in the beam 1. At the other end (not shown) of the beam 1, the piezoelectric transducer 11 of the element 3 receives the ultrasonic waves emitted by the transducer 11 of the element 2.
FIG. 1 shows that the detectors of the heads 2, 3 are electrically connected to a box 4 which houses the electronic devices indicated below, and which has a keyboard 5 and a display 6, for example of the LCD type. FIG. 2 shows that these connections are made by cables, such as 7, ensuring the transmission of the information passing from the detectors to the electronic devices which are in the box 4.
The purpose of the keyboard 5 is to provide these devices with data supplied by the operator, for example the length of the beam and a code number corresponding to the type of material (for example species of tree) of which the beam 1 is made.
In the Example according to FIG. 1, an ultrasonic wave is emitted by the device 11 of the head 2 (FIG. 2) and received by the same element of the identical head 3.
The information provided by the two devices 11, by the probes 10, 12 of the two heads 2 and 3 and by the two thermistors 13 of 2 and 3
REFERENCES:
patent: 2740032 (1956-03-01), Bouyoucos
patent: 2959959 (1960-11-01), Wellcowitz
patent: 3844163 (1974-10-01), Di Leo
patent: 3979581 (1976-09-01), Receland
patent: 4201093 (1980-06-01), Logan
patent: 4413518 (1983-11-01), Jones
patent: 4876889 (1989-10-01), Shakkottai et al.
Roulet Alain
Sandoz Jean-Luc
Finley Rose M.
Sandes S.A.
Williams Hezron E.
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