47 results about "Nominal stress" patented technology

This need is met by the present invention wherein structural stress in a fatigue-prone region of a structure is determined by using the nodal forces and displacement values in the fatigue-prone region, or equilibrium-equivalent simple stress states consistent with elementary structural mechanics in the fatigue-prone region. The determination is substantially independent of mesh size and is particularly well-suited for applications where S-N curves are used in weld fatigue design and evaluation, where S represents nominal stress or stress range and N represents the number of cycles to failure. The present invention is directed to structural stress analysis through various combinations of modeling, calculation, and direct measurement schemes.

The utility model discloses a method using a spherical indenter for measuring the phase transition properties of shape memory alloy (SMAs). The phase transition is induced under the pressure of the spherical indenter pressed into the surface of the shape memory alloy; the load signals and the displacement signals in the unloading process are detected by a sensor at the same time, and the ht curve of the load F-displacement is obtained; the load-displacement curve obtained in the test is transformed to a corresponding nominal stress Sigmam-nominal stress Epsilonm curve according to the analysis; then properties of the transformation stress, the elastic modulus and other aspects of the SMAs can be obtained. The test method has advantages that the method is easy in operation, and the nondestructive measurement of the materials can be elementally realized; the method not only can be widely used in the measurement of the phase transition properties of various super-elastic and shape memory SMAs, but also is particularly suitable for the phase transition measurement of the SMAs films with the low thickness only up to a plurality of micrometers or the SMAs micro devices with the micrometer order typical structure size; the method has accurate and precise measured value, which can supply the reliable measurement basis of the phase transition property for the application of the SMAs in the micro-electro-mechanical system.

The invention discloses an arm frame structure fatigue strength monitoring method, device and system and a fire truck. The monitoring method comprises the following steps: receiving stress value of at least one detection point of an arm frame structure in working state; for each detection point, calculating accumulated fatigue nominal stress frequency thereof according to the stress value thereof; and determining maintenance and / or scrapping of the arm frame according to the accumulated fatigue nominal stress frequency and preset maintenance frequency and / or preset scrapping frequency. The method can prevent the fatigue strength of the arm frame from being misjudged, and the arm frame can be maintained and / or scrapped in time, thereby improving usage efficiency and work security of the arm frame.

A bearing design method for butt welding joint fatigue and the like relates to the technical field of welding. The purpose of the present invention is to improve the fatigue bearing capacity of the welded joint by designing the geometric shape of the butt welded joint's excess height. The welded joints are abstracted into heterogeneous materials, and the base metal and welding consumables are correspondingly abstracted into homogeneous materials. According to the fatigue failure process of homogeneous materials, the fatigue life estimation method of homogeneous materials based on the nominal stress SN curve is obtained. The life estimation method estimates the number of stress cycles experienced when a fatigue crack expands to a certain size in a homogeneous material. The fatigue life estimation method for homogeneous materials is extended to heterogeneous materials, and a fatigue life estimation method for heterogeneous materials is obtained. Low-alloy high-strength steel Q550 and welding wire ER70S-6 are used as experimental materials to carry out load-bearing design and experimental demonstration of double Y-shaped butt joint fatigue. Fatigue bearing capacity.

The invention relates to a safety analysis method of an axis system during variable frequency operation of a motor. The method comprises steps of 1), testing dynamic torque signals on a rotation shaft near a diaphragm coupling during variable frequency operation of the motor, and acting the dynamic torque signals to a diaphragm of the diaphragm coupling and the rotation shaft so as to obtain torsional stress borne by the rotation shaft and dynamic tension and compression stress borne by the diaphragm; and 2), according to working features of the rotation shaft and the diaphragm coupling, using a nominal stress method to calculate fatigue life of the rotation shaft under the effect of high cycle load, and using a local stress method to calculate the fatigue life of the diaphragm under the low cycle load, and using a quite small value of the two kinds of calculated life to estimate the fatigue life of the axis system. Compared with the prior art, the safety analysis method is advantageous in that the safety analysis method is simple and feasible, and effects of steady-state and dynamic torque on the rotation shaft of a variable frequency driving motor are considered.