15 results about "Back stress" patented technology

Ceramic honeycomb bodies and methods for their manufacture are provided. The ceramic honeycomb body comprises a bulk density of less than 210 g / L, a geometric surface area (GSA) greater than 93 in−1 (3.66 mm−1), a mechanical integrity factor (MIF) greater than 0.28%, and a back pressure factor (BPF) greater than 0.4 mm2.

The high-precision stamping equipment comprises an upper die assembly, a lower die assembly, a female die, a punch and a back pressure mechanism, the female die is fixed to the upper die assembly and faces the lower die assembly, and a model groove matched with the punch in shape is formed in the side, opposite to the lower die assembly, of the female die; a circle of first protrusions matched with the model groove in shape are arranged on the periphery of the model groove. The punch is arranged on the lower die assembly and faces the model groove. The lower die assembly comprises a lower die base and a base plate arranged on the lower die base. The back pressure mechanism is fixed to the lower die base, and one end of the back pressure mechanism makes contact with the base plate. The device has the effect of improving the punching precision of general punching equipment.

These are individual walls (1) of modular dimensions with the confronting side edges (2) enabling the beveled finish to be mounted, so that the junction of four walls (1) at 90° create a modular junction box (3), each with a groove (8) at 90° and a rib (9) at 45° that enables assembly by sliding and double locking, configuring back pressure fittings between said walls (1).

The utility model discloses an anti-backpressure radial seam structure bracket assembly for a positive arch slotted rupture disk, which relates to the technical field of rupture disks, and comprises a positive arch slotted rupture disk, an upper lining film, a sealing film, a lower lining film and a novel backpressure-resistant bracket which are sequentially arranged from top to bottom and matched in shape, according to the radial seam structure bracket assembly for resisting back pressure of the forward-arch slotted rupture disk, the bracket supporting plate is arranged below the bracket radial seam in a spot welding mode, and when the bracket assembly is combined with the large-diameter forward-arch slotted rupture disk for use, the bracket can be prevented from integrally flying out along the circular seam to generate fragments; according to the utility model, the expandability is strong, and simple adjustment is carried out according to the bursting pressure, the back pressure and occasions with strict requirements on no fragments, so that the device can be used in different working conditions.

This invention relates to the field of medium-high entropy alloy technology, specifically to a high-strength and high-toughness multi-level heterogeneous medium-entropy alloy and its preparation method. This invention discloses a CoNiVAlTa-based medium-entropy alloy, which, through compositional design and process adjustment, utilizes low-temperature pre-aging to induce metastable phase transformation, followed by high-temperature recrystallization to achieve grain refinement and precipitation of multi-level strengthening phases. By introducing multiple strengthening mechanisms—grain refinement strengthening, precipitation strengthening, and back stress strengthening—the material possesses both high strength and high plasticity. This series of alloys exhibits a tensile strength of 1460 MPa to 1615 MPa at room temperature and a fracture elongation of 15% to 27%. This high-strength and high-toughness multi-level heterogeneous medium-entropy alloy not only boasts excellent comprehensive mechanical properties but also features a simple and feasible process, demonstrating great promise for engineering applications.

To perform establishment by a finite element method using a macroscopic yield function capable of expressing a Bauschinger effect.SOLUTION: Provided is a finite element method using a constitutive expression in which a macroscopic stress is decomposed into components of a shear stress of a slip system by a Taylor factor to obtain a strain rate. In the crystal plasticity, since the Bauschinger effect was exhibited even without rotating the crystal, it was confirmed that the Bauschinger effect was exhibited by the back stress. Therefore, the Taylor factor is set to a constant. This is a program of a finite element method accompanied by a macroscopic constitutive expression obtained by improving a constitutive expression of crystal plasticity. The finite element method is composed of a constitutive expression, a yield function, and an expression representing plastic strain. This corresponds to the heart of the finite element method.SELECTED DRAWING: None

The invention provides an improved Chboche model suitable for friction stir welding. According to the improved Chboche model, the tension and compression response is judged through the difference value between elastic tentative stress and total back stress; equivalent plastic strain and process peak residual strain are introduced to characterize elastic modulus degradation and isotropic softening and softening behaviors; characterizing follow-up hardening by adopting superposition of multiple groups of independent nonlinear components; and respectively calibrating elastic modulus degradation, isotropic softening and softening and follow-up hardening parameters of the tensile domain and the compression domain so as to realize optional tension-compression response asymmetry modeling. The invention further provides a parameter identification method of the improved Chboche model suitable for friction stir welding. According to the method, by improving the multi-mechanism coupling characterization capacity of the Chboch model and combining the swarm intelligence optimization algorithm, an efficient tool is provided for fatigue life prediction and structure optimization of the friction stir welding joint, and the engineering application value of numerical simulation is remarkably improved.

The present application relates to a kind of fastening process fastening effect evaluation method considering internal stress, comprising: simulating the fastening process to be evaluated, fastening, unloading and reverse fastening are carried out to fastener sample, and the stress and strain of different time are obtained;Multiple stress and strain points in stress and strain coordinate system are obtained;According to the multiple stress and strain points of unloading and reverse fastening process, the elastic segment region of unloading and reverse fastening process is obtained;The maximum stress and minimum stress of each stress and strain point in the elastic segment region are obtained, respectively as the upper limit of elastic segment and the lower limit of elastic segment;The back stress of fastener sample is determined;According to the back stress of fastener sample, the fastening effect evaluation result of the fastening process to be evaluated is obtained.The fastening process fastening effect evaluation method considering internal stress of the present application uses the back stress of fastener sample to evaluate fastening effect, so as to consider the influence of fastening process on fastening effect, to accurately assess the fastening effect of fastener.

The application discloses a kind of ceramic matrix composite nonlinear stress-strain relationship evaluation methods, comprising the following steps: step 1. carry out the stress-strain relationship evaluation test of ceramic matrix composite;Step 2. according to test data, the parameters of anisotropic yield function and the evolution equation parameters of anisotropic back stress increment are determined;Step 3. by relevant plastic flow rule, inelastic strain is obtained;Step 4 and step 5 determine the elastic stress-strain relationship with damage;Step 6 selects the numerical simulation method based on incremental theory: complete implicit reflection algorithm is used as stress-strain relationship updating algorithm.The nonlinear stress-strain relationship evaluation method proposed in the application introduces back stress evolution to simulate the ratchet effect of ceramic matrix composite hysteresis loop under uniaxial cyclic loading, and the model is simple and easy to use, and the required test amount is small, which saves cost.

According to the Mo-Si-B alloy with the harmonic structure and the preparation method of the Mo-Si-B alloy with the harmonic structure, the distribution state, the volume fraction and the grain size of all phases of the Mo-Si-B alloy can be accurately controlled through the method, and units with the large size, the medium size and the small size are distributed in a harmonic structure characteristic mode; further, good effects of back stress strengthening, crack passivation and the like are generated by utilizing a multi-stage size unit structure, so that the obdurability of the alloy is improved, meanwhile, a passivation layer is assisted to quickly grow at a high temperature, and the excellent high-temperature oxidation resistance of the alloy is kept. The strength, toughness and oxidation resistance of the alloy can be synergistically improved.

In the crystal plasticity finite element method, it was necessary to represent the crystal orientation in the data in order to determine the anisotropy caused by differences in crystal orientation. Furthermore, many finite element methods using yield functions exhibit isotropic hardening. [Solution] The crystal orientation was changed to represent the Taylor factor M. In other words, for a face-centered cubic lattice, the data for the 12-slip system could be rewritten in terms of the Taylor factor M. Furthermore, by including the deviated back stress, the Bauschinger effect could be expressed. This is not possible for rigid-plastic properties.

The invention discloses a dual-isomerism high-elongation metastable-state beta titanium alloy and a preparation method and application thereof, and belongs to the technical field of titanium alloy materials. The invention discloses a double-isomerism high-elongation metastable-state beta titanium alloy which comprises Ti and the following components in percentage by mass: 11.3-13.5% of Mo, 5.4-6.8% of Zr, 1.4-2.3% of Fe and inevitable impurities, and the preparation method comprises the following steps: mixing and smelting the raw materials of the components to prepare a metastable-state beta titanium alloy cast ingot; the metastable-state beta titanium alloy cast ingot is sequentially subjected to hot rolling and solution treatment, and therefore the double-isomerism high-elongation metastable-state beta titanium alloy coupling beta matrix isomerism and alpha precipitated phase heterogeneous distribution is constructed. According to the double-isomerism high-elongation metastable-state beta titanium alloy, due to back stress induced strengthening hardening brought by a novel double-isomerism microstructure of the double-isomerism high-elongation metastable-state beta titanium alloy, the good tensile property that the elongation reaches up to 23% at the room temperature is achieved, and the yield strength reaches up to 966 MPa.

The present invention provides a gap clamping and back pressure regulating device for inner wall ring groove structures and the like and a method for using the same. In order to overcome the problem in the prior art that a sudden pressure drop occurs in the machining gap during the electrolytic machining of the inner wall ring groove structure of difficult-to-cut metal materials, resulting in low machining quality and precision. The technical solution of the present invention includes a hollow pipe fitting composed of frustums A, B, C, and D from top to bottom, with a variable diameter. Notches are longitudinally provided on the pipe walls of the frustums A and D at the upper and lower ends, and threads are also provided on the circumferences of the frustums A and D. Nuts are provided on the threads to achieve the closing of the frustums A and D through the nuts; the inner wall of the frustum B is annularly fixed with a number of fan-shaped bosses of the same structure. After the fan-shaped bosses gather toward the center, they are spliced into a circle, and the diameter of the circle is larger than the machining surface diameter of the tool cathode by 0.3-0.5mm. The clamping of the tool cathode and anode workpiece is achieved by the same hollow pipe fitting, which prevents the annular groove from deviating and ensures the machining precision of the annular groove.