Shrink Range Research Articles

Elastoplastic Analysis of Ultimate Bearing Capacity for Multilayered Thick-Walled Cylinders Under Internal Pressure

The elastoplastic analysis based on the unified strength theory was performed to evaluate the ultimate bearing capacity of double- and multilayered thick-walled cylinders. The theory provides a new concept and method for the analysis of thick-walled cylinders. The solutions derived herein are widely applicable and can quantitatively account for different tension-compression strength values and mean principal stress. The fundamental solutions for single radii, assemblage pressure, and shrink range are derived with the yield condition of the theory. The traditional existing elastoplastic results by the Tresca or von Mises yield criteria can be seen as a particular case of the new solutions that can overcome shortcomings. The strength parameter, tension-compression strength ratio, radii ratio, and combined cylinder layers were taken as major theory variables for the unified solutions. The new solutions are versatile and can be adapted to the existing formulas, to more accurately calculate the structural stress conditions. The strength theory effect due to adopting different yield criteria is quite significant, which cannot be underestimated.

An intensive exploration on structure transformation of talc under γ-ray irradiation at 0–1000 kGy

To have a clear cognition on whether clay could be used for disposal of high level radioactive waste efficiently or not, in this work, talc was irradiated by Co-60 γ ray in air at a dose rate of 54 Gy/min with doses up to 1000 kGy. Then, variations in chemical/crystalline structure and intrinsic mechanism were explored. Main results show talc occurred dehydroxylation and lattice shrink. Under 0–1000 kGy irradiation, shrink range in (002) lattice plane was near 1.5% close to 0.14 A. Main mechanisms involve framework/Mg–OH bond break and H2O radiolysis. Framework break seems more important, Mg–OH bond break and H2O radiolysis are secondary. It seems talc exhibits poor stability to radiation. Clay matrix mightn’t ensure the effectiveness of disposal project, the effect of nuclear accident to environment can be serious.

Research on Melting Erosion Law of a Multiturn Series–Parallel Railgun During Launching Period

The melting erosion law of the contact interface between armature and rails on the electromagnetic (EM) railgun is one of the key factors affecting the launching performance. In order to study the melting erosion law on the contact interface of a multiturn series-parallel (MSP) railgun, an EM structure thermal multiphysical field coupling model is built, and the armature velocity, contact force, and temperature of contact interface under different current peak values and shrink ranges are analyzed. Besides, the related verification experiments are carried out, and the melting erosion law of the contact interface is obtained. The results of simulations and experiments show the following conclusions: First, during the launching, the contact force between armature and rails varies with current fluctuation. Second, the friction heat power varies directly with the contact force, but Joule thermal power caused by contact resistance varies inversely with the contact force. Third, the ambient temperature of the sliding contact interface can be further improved by reasonable design of armature shrink range. Fourth, due to the inevitable wear during sliding, the melting area of the armature contact surface gradually transfers from the initial contact area to the tail. The above-mentioned conclusions can provide a technical reference for the high-speed experimental study of MSP railgun.

Strength Analysis for Surface-mounted Permanent Magnet Rotor in High-Speed Motor

In the surface-mounted high-speed permanent magnet motor, the magnets are not mechanically strong enough to bear the centrifugal stress resulted from the high speed rotating, thus a sleeve composed of the carbon-fiber bandage is usually employed to retain the permanent magnets on the rotor surface. According to the surface-mounted high-speed permanent magnet rotor retained by a carbon-fiber bandage, in this paper, an analytical model for calculating rotor strength was presented based on the theory of elastic mechanics. Then the results of analytical model were compared with the calculations of finite-element method. It was shown that the analytical model proposed in this paper could accurately predict the stress distribution of the surface-mounted high-speed permanent magnet rotor fixed by a carbon-fiber bandage. Finally, the influence of the bandage thickness and shrink range between the permanent magnets and the bandage on rotor stress was investigated based on this analytical model of rotor strength.

Strength Design on Permanent Magnet Rotor in High Speed Motor Using Finite Element Method

The permanent magnets can be damaged for the tremendous centrifugal stress when the permanent magnet rotor rotates in high-speed. In this paper, the mechanical strength of high-speed permanent magnet rotor was researched. Stability operation mechanical conditions of the surface-mounted permanent magnet rotor were analyzed. The mathematical model between the shrink range of bandage and the maximum operating speed were concluded. The strengths of two kinds of surface-mounted permanent magnet rotors were calculated and compared using contact finite element method. For buried type permanent magnet rotor, the equivalent ring method was put forward to calculate its stress limit. The mathematical relationships between the maximum velocity and iron bridge thickness has been deduced. Using finite element method, the stress distributions was analyzed. The research results have shown that the high speed permanent magnet rotors designed according to the method proposed here had the adequate mechanical strength. DOI : http://dx.doi.org/10.11591/telkomnika.v12i3.4675

An improved optimal design scheme for high voltage cable accessories

Cable accessory always fits cable with a shrink range in order to ensure a certain interface pressure in the actual use, so cable accessory keeps in the expansive state after installation. But the expanded accessory will lead to not only a thinner insulation thickness and a shorter length but also a possible problem in the accessory, as the angle of stress cone and the shape at end of high voltage (HV) shielding tube may far deviate from the original design structure. This will be a vital threat to the reliability of cable accessory in service. In this paper, an improved design scheme for HV cable accessories was proposed to ensure the optimum electrical design after installation. The key process was the deduction of deformation and displacement equations of cable accessory during expansion by the theory of elastic mechanics. As joints are always much weaker than terminations in the cable system, the case studies were conducted only on cable joints in this paper, and the electrical fields were calculated to evaluate their performances. By contrast with the electrical field distributions before and after improvements, the results show that the expansion will not only change the joint structure but also aggravate the electrical fields at the interface or in the bulk of the joint. At last, a comparison was made on an actual cable joint which kept in the expansive or relaxation state, so as to verify the correction of the deformation and recovery equations proposed in this paper. This improved design scheme can also be applied for termination design, especially be great helpful for the higher or extra HV cable accessories' manufacture and the long-term operation safety.

Numerical Simulation and Analysis of Tapered Interference Fit of Atomizer Disk

The contact analysis model of high speed centrifugal atomizer is created and stress distribution law is obtained by using ANSYS FEM software in this paper. The stress distribution along the axial direction is uneven, the stress of the small end of the taper is large and the stress concentration appears on both ends of the taper. In addition, the factors which influence the interference fit stress are researched and discussed. The interference fit stress is mainly influenced by the shrink range, while the influence from the friction coefficient is very weak. Comparing with the conventional design, the position and value of the stress and deformation of the parts can be known exactly and thoroughly by using the approach proposed in this paper. The method provides a very valuable reference to designing the best shrink range for engineering application.

Three Dimensional Finite Element Interference Contact Analysis about Cone Screw and Bush of Opposed Biconinal Cone Screw High-Pressure Seawater Hydraulic Pump

The main components of the opposed biconinal cone screw high-pressure seawater hydraulic pump is the rubber bush and metal cone screw, and the interaction of the bush and cone screw is one of the main factors affecting the novel pump performance. The deformation and stress of the bush and cone screw under the initial interference is analyzed by the nonlinear finite element analysis. The analysis shows that: under the effect of the initial interference, large displacement is present to the radial surface of the cone screw, and the displacement of the radial surface mainly affects the displacement vector sum of the cone screw, and the deformation decreases gradually from the middle to the ends of the cone screw, while the cone screw is bending; the deformation in three direction of the bush is close to each other, but the location of the maximum displacement in each direction is different; with the shrink range increasing, the deformation of the cone screw and bush increases, but the deformation of the cone screw is much smaller than that of bush, so the deformation of the bush mainly affects the seal between the cone screw and bush, and the shrink range between the cone screw and bush decreases because of the deformation of the bush. Over the role of the interference force, the maximum von mises stress of the cone screw is an order larger than that of bush, and the maximum von mises stress both increases with the shrink range increasing; although shrink range is different, the location of the maximum von mises about the cone screw and bush is the same.

Stress distribution and fatigue life of built-up sleeved backup roll

The advantage of built-up sleeved backup roll was described. Based on the stress distribution analysis and simulation for the built-up sleeved backup roll by using finite element method, the effects of roll sleeve thickness and shrink range on the stress-strain field were studied. Finally, based on the methodology and strategy of the fatigue analysis, fatigue life of backup roll was estimated by using the stress-strain data obtained through finite element simulation. The results show that roll sleeve thickness and shrink range have a great influence on sleeve stress distribution of built-up sleeved roll. Under the circumstance of ensuring transferring enough torque, the shrink range should be kept small. However, thicker roll sleeve has longer roll service life when the shrink range is constant.

Failure Analysis of the Stuffing Box in a Super High Pressure Compressor

In this paper, theoretical and experimental researches were done to find the repeated cracking reason of stuffing box in a super hyper pressure compressor. The mathematical expression of the assembly pressure was deduced in interference fit. From macro and micro perspectives, residual stresses were measured by X-ray diffraction in typical position of stuffing box when the packing box in combination and separation states. Besides, metallography and fracture examinations were carried out. The results showed that the real magnitude of shrink range of the failed stuffing box was only account for 12% of the designed size requirements, however, under this working condition this stress was not sufficient to cause cracking; Unqualified smelting process and tensile stress concentration in tank caused micro crack, which finally results in fracture of the stuffing box under fatigue mode.

The Study of Shrink Fit Design Empirical Formula

The regulation of stress concentration generated by the edge effect of shrink fit is studied in this paper. Firstly, experiment is designed with Latin hypercube (LH) method; then the maximum compound stress of the shrink fit is obtained by means of FEM; at last, the relationship among the maximum compound stress, shrink range, dimensional sizes of the shrink fit parts and material properties is fitted into a empirical formula via BP neural network. The formula is capable of offering good forecast to the maximum compound stress, and makes up the deficiencies of the design of shrink fit by using elastic mechanics (EM). At the end of this paper, the shrink fit of the drive axle housing is optimized with the empirical formula, and the maximum compound stress is abated greatly on the condition of ensuring the normal use of drive axle housing.

A 3D FEM Methodology for Air Hammer Bit Design

Based on the failure mode of air hammer bit, a mechanical model of the tooth on the inclined plane is established. And then a new air hammer flat bit with double declined planes and a big central plat (the outer inclined plane is 40° and the inner one is 20°) is designed. In order to reduce the design cost and cut down the design cycle, we establish a 3D contact model of 12 1/4″ full-scale flat bit, teeth and rock to choose a better end face structure from single and double declined planes, verify the rationality of bit parameters and tooth arrangement, design reasonable shrink range between tooth and tooth-Hole. This 3D FEM methodology for air hammer bit design is economical and useful, it can be used to optimize bit structure and design a new bit.

Contacting Model Considerations of Interference Fit for Shaft-Hub System

In this study, a contacting model was investigated for interference fit shaft–hub system (rotor system) on rotational speed 30000 r/min by finite element method (FEM) which gives more complete and accurate results than the traditional method. 2-d and 3-d FEM contacting models were established first; then the stress distribution and contact state of rotor system which containing four interference fit couples were analyzed with the contacting FEM model system while the rotor system rotates on 30,000r/min. Finally, an optimal design of shrink range of the rotor system above was debated.