Device for measuring biaxial stress-strain

Claim 1

A DEVICE COMPRISING A FLAT POROUS PLATE SUPPORTED AT ITS PERIPHERY BY A BASE MEMBER, ANNULAR CLAMPING MEANS FOR COOPERATING WITH SAID BASE MEMBER TO FIXEDLY ENGAGE THE PERIPHERAL EDGE OF A SHEET OF EXPANDABLE MATERIAL AND INITIALLY POSITION ONE SIDE THEREOF IN CONTINUOUS CONTACT WITH SAID PLATE, MEANS FOR SUPPLYING COMPRESSED INERT GAS AT A CONTROLLED RATE THROUGH SAID PLATE AND TO SAID SIDE OF THE SHEET TO THEREBY BLOW THE SHEET INTO A UNIFORM CURVED SHAPE, MEANS FOR CONTINUOUSLY MEASURING AND RECORDING THE GAS PRESSURE THUS APPLIED, MEANS FOR CONTINUOUSLY MEASURING AND RECORDING RADIUS OF CURVATURE OF THE SHEET AS IT EXPANDS, AND MEANS FOR CONTINUOUSLY MEASURING AND RECORDING THE STRAIN ON SAID SHEET, THE STRAIN MEASURING MEANS COMPRISING A LOWSTARTING-TORQUE POTENTIAL DIVIDER HAVING A ROTATABLE SHAFT, A DRIVE PULLEY FASTENED TO SAID SHAFT, A THREAD HAVING ONE OF ITS ENDS WRAPPED AROUND SAID PULLEY, ANCHOR MEANS FOR FASTENING THE OTHER END OF SAID THREAD TO A POINT ON THE SURFACE OF SAID SHEET OPPOSITE ITS SAID ONE SIDE, AND GUIDE MEANS FOR SLIDABLY HOLDING SAID THREAD CONTIGUOUS TO A SECOND POINT ON SAID SURFACE, SAID FIRST AND SECOND POINTS DEFINING A STRAIGHT LINE ORIGINALLY PASSING THROUGH THE CENTER OF THE AREA OF SAID SHEET WITHIN THE CLAMPING MEANS, AND SAID THREAD BEING ADAPTED TO PAY OUT THROUGH SAID GUIDE MEANS AND TURN SAID PULLEY AS THE LENGTH OF THE ARC BETWEEN SAID POINTS ON THE SURFACE OF THE EXPANDING SHEET INCREASES.

Claim 2

A DEVICE COMPRISING A FLAT POROUS PLATE SUPPORTED AT ITS PERIPHERY BY A BASE MEMBER, ANNULAR CLAMPING MEANS FOR COOPERATING WITH SAID BASE MEMBER TO FIXEDLY ENGAGE THE PERIPHERAL EDGE OF A SHEET OF EXPANDABLE MATERIAL AND INITIALLY POSITION ONE SIDE THEREOF IN CONTINUOUS CONTACT WITH SAID PLATE, MEANS FOR SUPPLYING COMPRESSED INERT GAS AT A CONTROLLED RATE THROUGH SAID PLATE AND TO SAID SIDE OF THE SHEET TO THEREBY BLOW THE SHEET INTO A UNIFORM CURVED SHAPE, MEANS FOR CONTINUOUSLY MEASURING AND RECORDING THE GAS PRESSURE THUS APPLIED, MEANS FOR CONTINUOUSLY MEASURING AND RECORDING RADIUS OF CURVATURE OF THE SHEET AS IT EXPANDS, AND MEANS FOR CONTINUOUSLY MEASURING AND RECORDING THE STRAIN ON SAID SHEET, THE STRAIN MEASURING MEANS COMPRISING A LOWSTARTING-TORQUE POTENTIAL DIVIDER HAVING A ROTATABLE SHAFT, A DRIVE PULLEY FASTENED TO SAID SHAFT, A THREAD HAVING ONE OF ITS ENDS WRAPPED AROUND SAID PULLEY, ANCHOR MEANS FOR FASTENING THE OTHER END OF SAID THREAD TO A POINT ON THE SURFACE OF SAID SHEET OPPOSITE ITS SAID ONE SIDE, AND GUIDE MEANS FOR SLIDABLY HOLDING SAID THREAD CONTIGUOUS TO A SECOND POINT ON SAID SURFACE, SAID FIRST AND SECOND POINTS DEFINING A STRAIGHT LINE ORIGINALLY PASSING THROUGH THE CENTER OF THE AREA OF SAID SHEET WITHIN THE CLAMPING MEANS, AND SAID THREAD BEING ADAPTED TO PAY OUT THROUGH SAID GUIDE MEANS AND TURN SAID PULLEY AS THE LENGTH OF THE ARC BETWEEN SAID POINTS ON THE SURFACE OF THE EXPANDING SHEET INCREASES.