Abstract: A device for testing the fatigue vibration strength consists of a framework carrying a spring-mounted vibrating body, an electromagnetic exciter arranged between the vibrating body and one holding element to hold the test body. There is also an adjustable threaded spindle for the purpose of superimposing a static load on the vibrating load affecting a test body during a vibration strength test. The exciter is provided with two parts which are movable in relation to one another, the one part being connected to the vibrating body and the other to the aforementioned holding element. The two exciter parts are connected to one another by elastic rod shaped members. These are dimensioned in such a manner that in all foreseen operating conditions an air gap remains between the exciter parts permitting vibration excitation with good efficiency.

Abstract: A method of, and apparatus for, determining the time dependency of the length of a fissure in a test specimen during a fracture test which comprises securing an electrically conductive, areal or surface-like element to the test specimen such that during the fracture test it tears at the region of the fissure. An electrical parameter, such as the electrical resistance is determined between two measuring locations of the element. The measuring locations are selected such that the measurement current between such measuring locations passes through the region of the fissure. The element which is employed has a compact measuring section which is free of openings and the element is secured at the test specimen in such a manner that the measuring section completely covers the surface region which is occupied, during the fracture test, by the fissure until the end of the measurement of the length of the fissure, so that the resistance substantially uniformly increases with the length of the fissure.

Abstract: An osteosynthetic pressure plate includes a slot formation for receiving a bone-fixing screw which is adapted to be secured to a bone part which is to be mended. The slot is formed with an edge which includes an oblique portion or ramp having an inclination such that when it is engaged by the underside of a head portion of a bone-fixing screw there will be a displacement of the pressure plate in a direction to move the ramp portion away from the fixing screw and to cause the plate to apply a pressure to hold the bone parts in tight engagement. The plate is advantageously useable with screws having heads of spherical form or conical form, for example.

Abstract: An osteosynthetic pressure plate includes a slot formation for receiving a bone-fixing screw which is adapted to be secured to a bone part which is to be mended. The slot is formed with an edge which includes an oblique portion or ramp having an inclination such that when it is engaged by the underside of a head portion of a bone-fixing screw there will be a displacement of the pressure plate in a direction to move the ramp portion away from the fixing screw and to cause the plate to apply a pressure to hold the bone parts in tight engagement. The plate is advantageously useable with screws having heads of spherical form or conical form, for example.