Material analyzing apparatus and method

Abstract

An analyzing structure .Iadd.and method .Iaddend.for determining properties such as elastic shear modulus and mechanical hysteresis of a material. A pair of mutually spaced holders hold the sample in such a way that the holders are interconnected by the sample, and these holders are in turn carried by driver and driven supports. A drive sets the driver support into vibratory motion so that the latter is transmitted through the sample to the driven support. By detecting the manner in which the driver and driven supports vibrate it is possible to determine properties of the sample. The sample is tested by cyclically generating substantially pure shear forces in the sample, with the power required to sustain the vibrations of the sample at a constant level being measured to determine the damping of the sample and the frequency of vibration being measured to determine the modulus of the sample.

What is claimed is: 
     
       1. In an analyzer, a pair of mutually spaced holding means for holding a sample which is to be analyzed with said sample extending between and interconnecting said pair of holding means, driver support means carrying one of said holding means to support the latter for vibratory movement and driven support means carrying the other of said holding means to support the latter also for vibratory movement, drive means operatively connected with said driver support means for setting the latter into vibratory motion which is transmitted through said one holding means to said sample and from the latter to said other holding means to vibrate the latter and said driven support means therewith, whereby said driver support means and said one holding means, on the one hand, and said driven support means and said other holding means, on the other hand, form driver and driven units which are set into vibratory motion when said drive means operates with a vibratory motion being transmitted to said driven unit through said sample, and detecting means coacting with at least one of said units for responding to vibratory motion thereof for determining properties of the sample which is under test. 
     
     
       2. The combination of claim 1 and wherein said units operate on said sample to cyclically generate shear stresses therein. 
     
     
       3. The combination of claim 1 and wherein a temperature-regulating means coacts with said sample for regulating the temperature thereof. 
     
     
       4. The combination of claim 1 and wherein a second detecting means coacts with the other said units for responding to vibratory motion thereof for providing additional information with respect to the sample. 
     
     
       5. The combination of claim 4 and wherein a feedback means is operatively connected between said second detecting means and drive means for controlling the latter to maintain said driver unit in a state of resonant vibratory movement. 
     
     
       6. The combination of claim 1 and wherein said driver and driven support means respectively have the construction of a pair of identical upright springy tines, said pair of holding means respectively having the construction of a pair of identical clamps respectively carried by said tines and interconnected by said sample which is clamped by said clamps. 
     
     
       7. The combination of claim 6 and wherein a base is common to and carries said tines and is of sufficient mass and stiffness to prevent flexure of said base during vibratory movement. 
     
     
       8. The combination of claim 1 and wherein said detecting means includes a light-chopping means carried by said driven support means for movement therewith for modulating a light beam with a frequency determined by the vibratory motion of said driven support means, light-source means for directing toward said light-chopping means a light beam to be modulated thereby, and photosensitive means situated at the side of said light-chopping means opposite from said light source for responding to the modulation of the light beam by said light-chopping means to detect the vibratory motion of said driven support means. 
     
     
       9. The combination of claim 8 and wherein a second detecting means identical with said first-mentioned detecting means coacts with said driver support means for detecting the vibratory motion thereof. 
     
     
       10. The combination of claim 1 and wherein said detecting means forms the only detecting means of the analyzer, whereby there is no detecting means coacting with the other of said units. 
     
     
       11. The combination of claim 10 wherein said one unit is the driver unit. .Iadd. 12. The combination of claim 1 and wherein said drive means drives said driver support means at a fixed frequency determined by the sample properties. .Iaddend..Iadd. 13. The combination of claim 1 and wherein said driver support means and driven support means respectively cooperate with said pair of holding means for maintaining them at a constant distance from each other. .Iaddend. .Iadd. 14. Apparatus for dynamically analyzing properties of a sample comprising, in combination: a rigid base member,   a pair of sample holders adapted to grip said sample at spaced portions of said sample,   a corresponding pair of elongated, spaced support means for said holders secured distant from said holders to said base member,   drive means operatively connected to one of said support means for imparting lateral vibratory motion thereto, whereby said sample is subjected to vibratory motion transversely to said lateral vibratory motion,   detecting means associated with one of said support means responsive to vibratory motion thereof. .Iaddend..Iadd. 15. Apparatus as set forth in claim 14 which also includes feedback means coupled between said detecting means and said drive means for maintaining said vibratory motion at the resonant frequency of the structures comprising the sample, sample holders, and support means. .Iaddend..Iadd.16. Apparatus as set forth in claim 14 wherein said base member decouples said pair of support means whereby their vibration is about in phase. .Iaddend..Iadd. 17. Apparatus as set forth in claim 14 wherein said support means each have an axis which is parallel to each other. .Iaddend. .Iadd. 18. Apparatus as set forth in claim 17 which also includes feedback means coupled between said detecting means and said drive means for maintaining said vibratory motion at the resonant frequency of the structure comprising the sample, sample holder, and support means, and wherein said base member decouples said pair of support means whereby their vibration is about in phase. .Iaddend..Iadd. 19. Apparatus as set forth in claim 14 wherein said support means are resilient. .Iaddend..Iadd. 20. A method of dynamically analyzing a sample comprising the steps of:   securing said sample between a pair of spaced, dynamically decoupled, elongated support members,   subjecting one of said support members and hence through said sample the other of said support members to in phase lateral vibratory motion, thereby to stress said sample with a vibratory motion in a sense transverse to the sense of said lateral vibratory motion, and sensing said vibratory motion. .Iaddend..Iadd. 21. A method as set forth in claim 20 comprising the additional step of resonating the vibratory motion at the resonant frequency of said sample and said support members. .Iaddend..Iadd. 22. A method of dynamically analyzing a sample comprising the steps of:   cyclically moving the center of the mass of a sample along an arcuate path lying in a plane, and   simultaneously moving spaced portions of said sample in opposite senses in said plane transverse to said arcuate path, thereby to create stresses in said sample, and sensing said stresses. .Iaddend. .Iadd. 23. The combination of claim 14 and wherein said pair of support means are secured at one end to said base member..Iaddend.