T-shape Tube Research Articles

A research on the converging process in a T-shape tube

A T-shape tube is an important structure in chemical engineering and other fields. This article utilizes the CFD method on python with a simplified Navier-Stokes equation to stimulate the converging process of different fluids and studies the influence of inflow speed, viscosity, density, diffusion coefficient, the diameter of the tube and the length of the tube on the transmission characteristics like pressure and flow field. The results indicate that the ratio of the velocity of the main tube to that of the branch, the diameter of tube AC and tube B is inversely related with mixing efficiency and that the increase of pipe length at outlet tube and the diffusion coefficient of fluid is positive to the well-distributed concentration of outflow. However, the density and viscosity of inflow seem to have little impact on the mixing process.

Design of a Fiber Alkali Vapor Cell for Atomic Magnetometer for Magnetoencephalography Applications

Spin exchange relaxation free (SERF) atomic magnetometer (AM), based on the Larmor precession of alkali atoms, is considered a promising candidate for magnetoencephalography (MEG) systems with the advantages of high sensitivity and no need for cryogenic devices. The footprint of the sensor header contains alkali vapor cell and bulk optical elements determining the spatial resolution of the MEG system. Optical fiber could separate the vapor cell far from other parts of the sensor header to improve the spatial resolution. However, coupling between glass cell and fibers limits the coupling loss of the light. Here, we describe the design of a fiber-based alkali vapor cell that could alleviate these issues. A pair of fiber cables combining a polarization maintaining fiber (PMF) and hollow-core photonic crystal fibers (HC-PCFs) are enclosed in a vacuum-sealed T-shape glass tube filled with alkali atoms. The fiber cell ensures a flexible integration with most fiber systems. The fiber structure, with an air gap between HC-PCFs, provides a large interaction volume between light and atoms. The vapor of the alkali atoms diffuses into the air core of the HC-PCF from the glass tube by heating. The alkali atoms still contained in SERF regime are within the wall relaxation rates of 12,764 s−1 in the coating fiber cell. The insertion loss due to fiber coupling is analyzed. The coupling efficiency could be 91%, with the fiber structure consisting of a 40 μm diameter HC-PCF and a 1 mm air gap. The limit sensitivity under this condition is simulated at 14.7 fT/Hz1/2. The fabrication technique and the light insertion loss are discussed. The fiber alkali vapor cell is of compact size and has flexible integration with the fiber atomic spin precession detection system.

Characterization of mechanical properties for tubular materials based on hydraulic bulge test under axial feeding force

A T-shape tube hydraulic bulge test under axial feeding force is carried out to characterize the mechanical properties of EN AW 5049-O and 6060-O aluminium alloys. The punch displacement, T-branch height and axial compressive force are recorded online during the experiment. An intelligent inverse identification framework combining the finite element method and numerical optimization algorithm is developed to determine material parameters by fitting simulated results to the experimental data iteratively. The identified constitutive parameters using the inverse modelling technique are compared with those determined by the theoretical analysis and uniaxial tensile test. The comparison shows that the predicted bulge height and punch force based on the material parameters obtained by the three methods are different and the inverse strategy produces the smallest gap between numerical and experimental values. It is possible to conclude that the hydraulic bulge test can be applied to characterize the stress-strain curve of tubular materials at the large strain scope, and the automatic inverse framework is a more accurate post-processing procedure to identify material constitutive parameters compared with the classical analytical model.

A Finite Element Analysis Verification of a Machine-Trained Mathematical Model of T-Tube Hydroforming

An adaptive, heuristic, nonlinear mathematical model (AHNM) was proposed to optimize the loading path of successful tube hydroforming process through adaptive minimization of the internal pressure and axial load by using Multiple Ridge Regression (Machine learning technique). The AHNM model was implemented, solved, and optimized, and it was found that increasing the number of steps and starting with small increment enables the mathematical model to capture the non-linearity of the real model, which leads to minimizing the system requirements. In this paper Finite Element Modelling (FEM) was developed to verify and test the validity and reality of the implemented loading oaths from the AHNM model for hydroforming of T-shape tube having an elliptical protrusion. The objective function was measured, and the results of minimum thickness, and maximum protrusion height were verified. Besides, the tube was formed with a well wall thickness distribution. Consequently, it is confirmed that developing an adaptive heuristic nonlinear mathematical modelling is effective for obtaining a Loading Path for Hydroforming of a Tube Having an Elliptical Protrusion.

A sensitive and accurate analytical method for the determination of cadmium in food samples: Molybdenum coated T-shape slotted quartz tube flame atomic absorption spectrophotometry

In this study, a molybdenum coated T-shaped slotted quartz tube atom trap flame atomic absorption spectrophotometry method (Mo coated-T-SQT-AT-FAAS) was developed for the determination of cadmium with on-line preconcentration. Inner surface of T-SQT was coated with molybdenum to enhance the trapping efficiency. Hydrogen gas was used instead of organic solvents to release trapped atoms. Limit of detection and quantification were found to be 0.057 and 0.082 µg/L, respectively. The developed method has a linear working range between 0.10 and 1.0 µg/L with a low %RSD value (<3.7). About 1202 times enhancement in detection power was recorded over the conventional FAAS system. Recovery experiments were used to determine the applicability of the method developed to real samples (linden, milk powder and mint) and significant results (94.4–100.7%) were obtained for the samples spiked at 0.30, 0.50 and 1.0 µg/L. The method was also applied to Tomato Leaves 1573a SRM to check the accuracy.

Optimization of T-shape slotted quartz tube with exit holes-atom trap-flame atomic absorption spectrophotometry system for the accurate and sensitive determination of tellurium in tap water.

Tellurium has been widely used in industrial processes and daily life products, and can cause serious health problems upon exposure. Therefore, determination of tellurium in real-life samples is very crucial. In this study, an accurate, environmentally friendly, and inexpensive analytical method was developed to determine trace levels of tellurium in water samples. To lower the detection limits, system parameters including flame type, acetylene flow rate, slotted quartz tube (T-SQT) height, and trapping period were optimized. Under the optimum conditions, the limit of detection (LOD) and quantification (LOQ) were calculated as 14.1ng/mL and 47.1ng/mL, respectively. For recovery studies, the optimized T-SQT-AT-FAAS method was applied to tap water samples to determine trace levels of tellurium and recovery results were found between 91.1 and 111.3%. Relative standard deviation value (%RSD) of the developed method was found to be less than 5.0% even for the lowest concentration in calibration plot, specifying good accuracy and high applicability of the method for water samples. Graphical abstract .

Propagation of shock waves formed by explosion of the air-propylene mixture in a T-pipeline

The paper deals with mathematical modelling of the process of an explosion of a cloud of reactive gases and its impact on the environment. The research may be relevant to ensure fire safety and to prevent explosion hazards at industrial production facilities that use reactive gas mixtures as a working medium and at high-pressure industrial pipelines used for their transportation. The goal of the study is to develop and test a computational technology for numerical modelling of clouds of reactive gas mixture expansions and loads evaluation. To describe the chemical processes in the explosion, a simplified mathematical model is proposed which based on the assumption of frozen chemical reactions. Using the model, a set of User Defined Functions is implemented in ANSYS Fluent and applied for solving a problem of a “propylene-air” cloud explosion inside the T-shape tube with two closed and one open ends.

The multi-objective non-probabilistic interval optimization of the loading paths for T-shape tube hydroforming

The focus of presented paper is to find a reliable Pareto front of the loading paths for T-shape tube hydroforming (THF) process using multi-objective non-probabilistic interval optimization method. Three indicators are included to measure the forming quality of THF process: the contact area is used to evaluate the calibration degree; bursting failure is estimated by the maximum thinning ratio and the protrusion height is also taken into consideration. The reliability-based degree of interval of constraints is employed to guarantee the reliability of THF process. A validated finite element model is adopted to conduct virtual experiments. The percentage contributions of the loading parameters for each indicators are calculated by the Taguchi method, and some significant parameters are identified and the dimensionality of the design variables can be reduced. The support vector regression model whose accuracy is calculated by leave-one-out cross-validated method is adopted to improve the optimization efficiency for the determination of the Pareto front. The Pareto fronts of uncertain optimization and deterministic optimization are compared, and the results show that more reliable solutions can be achieved by the presented method.

The multi-objective optimization of the loading paths for T-shape tube hydroforming using adaptive support vector regression

The objective of this study is to introduce adaptive support vector regression, whose accuracy and efficiency are illustrated through a numerical example, to determine the Pareto optimal solution set for T-shape tube hydroforming process. A validated finite element model developed by the explicit finite element code LS-DYNA is used to conduct virtual T-shape tube hydroforming experiments. Multi-objective optimization problem considering contact area between the tube and counter punch, maximum thinning ratio, and protrusion height is formulated. Then, the Latin hypercube design is employed to construct the initial support vector regression model, and some extra sampling points are added to reconstruct the support vector regression model to obtain the Pareto optimal solution set during each iteration. Finally, the ideal point is used to obtain a compromise solution from the Pareto optimal solution set for the engineers.

New Method of Cold Forming by the Spheres for Pipe Converting to the T-shape Tube

Abstract In the current paper, finite element simulation for forming C12200 copper alloy and transforming it to T-shaped tube via balls has been done. The main purpose of this paper is to introduce a new cold forming method which is similar to hydroforming having the difference that instead of using fluid, metal and rigid balls have been used to form tube. Simulation results indicated that by decreasing the size of the balls, the rate of stress concentration in tube forming area will be increased and the rate of tube forming will be increased. Therefore, by applying smaller balls, the rate of tube forming can be increased. Also, results obtained from simulations showed that by applying larger balls in the mandrel's edge and smaller balls in forming area, rate of elements’ strain and also forming in the forming area will be increased.

A Kriging-based non-probability interval optimization of loading path in T-shape tube hydroforming

In this study, the interval optimization method, in which the bounds of uncertain parameters are only required and knowing their probability distributions are not needed, is introduced to deal with limited information in T-shape tube hydroforming. The contact area between the counter punch and the tube is taken as the objective function and the protrusion height and maximum thinning ratio as constraints. To control the possibility degree of failure associated to each constraint, the reliability-based possibility degree of interval method is adopted to evaluate the reliability of T-shape tube hydroforming process. Before optimizing the process, the finite element model is validated against experimental results, and Taguchi method is employed to screen key factors from a number of potential factors. In addition, to improve computation efficiency, the Kriging model is adopted to construct the surrogate model, and the performance of the resulting surrogate model is validated using cross-validated method. Finally, the Kriging based on interval optimization method is applied for loading path design in T-shape tube hydroforming, and the results show that the robustness and reliability of the process can be guaranteed.

The optimization of the loading path for T-shape tube hydroforming using adaptive radial basis function

The success of the T-shape tube hydroforming process requires a combination of internal pressure and axial and counter punch actions. The objective of this study is to introduce the adaptive radial basis function and demonstrate its accuracy and efficiency through a numerical example, to determine the optimal loading parameters in T-shape tube hydroforming process. The finite element model is developed with the explicit dynamic finite element code LS-DYNA and validated against the experimental work. The Taguchi method based on variance of analysis technique is used to screen the important loading parameters, which have a significant effect on the forming quality, such as the maximum thinning ratio, protrusion height and contact area, etc, from a number of potential loading parameters. The contact area is considered as the objective while the maximum thinning ratio and protrusion height are regarded as the constraints, and then the optimal loading parameters are obtained by adaptive radial basis function after several iterations. The results show that a significant improvement in the contact area is achieved while the results of the minimum thickness and protrusion height do not become worse.

The multi-objective robust optimization of the loading path in the T-shape tube hydroforming based on dual response surface model

In this study, a dual response surface model-based multi-objective robust optimization method is introduced to deal with the uncertainties in the tube hydroforming process. The objective of this study is to maximize the protrusion height and minimize the thinning ratio; meanwhile, the variations of the objectives should be minimized. A valid finite element model obtained from experimental result and LS-DYNA is employed to simulate the T-shape tube hydroforming process. To improve computation efficiency, radial basis function combined with Latin hypercube and orthogonal design sampling strategies is employed to construct dual response surface model, which are the mean and standard deviation response of the hydroforming process, respectively. The robust Pareto solutions can be obtained using NSGA-II; meanwhile, the ideal point method is used to obtain the most satisfactory solution from the Pareto solutions for the design engineers. As a conclusion, a significant improvement of the robustness can be achieved; however, the mean performance of the protrusion height has to be sacrificed.

Repeated tracheal resection for non-neoplastic restenosis

Treatment of patients with recurrent cicatrical tracheal stenosis after previous circular tracheal resection is one of the most difficult problems in thoracic surgery at present time. In most cases repeated radical surgery as new resection is declined in favour of palliative treatment. It is often associated with lingering or perpetual preserving of T-shape or tracheostomy tube and respiratory tract stenting. Development of thoracic surgery last years permits to perform repeated tracheal resections with restoration of respiratory tract integrity by using of new tracheal anastomosis. For the last 4 years 6 such operations were performed with satisfactory immediate and remote results. Diagnostic algorithm before repeated surgery is similar to those before primary intervention. Special attention should be attended to state of remained parts of respiratory tract, degree and length of stenosis and tracheomalacia which may be result of divergence of edges of the primary anastomosis. Preserving of not less than 1/4 primary length of intact trachea with its satisfactory mobility is main condition for this surgery because it will permit to perform new anastomosis without high tension. Risk of postoperative complications after repeated operations is not higher than those after primary resection. But at present time these operations are in competence of small number of specialists and medical institutions with serious experience in thoracic surgery.

Study of the Hydraulic Bulge Test in T-shape Hydroforming Die

Tube hydroforming uses internal pressure and axial feeding to form a tube into a desired shape. Finite element method may be used to predict the process results. One of the most important parameters for finite element analysis of tube hydroforming is the material properties of tube. The tensile test and the hydraulic bulge test are two methods for obtaining the material properties of tubular material. In order to investigate the finite element method for tube hydroforming in a condition similar to the actual tube hydroforming, the tube material properties must be determined by hydraulic bulge test. In this study hydraulic bulge test in T-shape die has been conducted. A new geometrical consideration has been done to use of the theoretical relation that constructed base on the free hydraulic bulge test. The stress-strain curve was obtained and evaluated in finite element method to simulate the actual T-shape tube hydroforming process. Comparisons between the results of FEM and actual tube hydroforming show good agreement.

Adaptive simulations in T-shape tube hydroforming with different outlet diameters

A successful tube hydroforming process depends largely on the loading paths for controlling the relationship between the internal pressure, axial feeding and the counter punch. The objective of this article is to propose an adaptive control algorithm to determine appropriate loading paths in T-shaped protrusion hydroforming with different outlet diameters. The finite element analysis is used to simulate the flow pattern of the tube during tube hydroforming process. The analytical flow line net configuration of the tube is utilized to determine the speed ratio of the counter punch to the axial feeding at the protrusion stage. Appropriate loading paths for different outlet diameters are determined using the proposed adaptive control algorithm. Different pressurization profiles are used in the tube hydroforming experiments. Experimental results show that a sound product is obtained using the pressurization profile determined by the proposed adaptive simulation algorithm. From the comparisons of the product shape and flow line net configurations between the analytical and experimental values, the validity of the proposed control algorithms is verified.

Development of In-process Fuzzy Control System for T-shape Tube Hydroforming

To develop an in-process fuzzy control system for tube hydroforming, a new die-embedded sensing system was developed and fuzzy control was used to determine adaptively suitable loading path. T-shape tube hydroforming experiments were conducted to confirm the validity of die-embedded system and in-process fuzzy control system. As a result, the validity of the die-embedded sensing system was confirmed. Besides, Evaluation functions were measured and the loading path was automatically determined in real-time. Furthermore, a T-shape tube was formed with a well wall thickness distribution. Consequently, it is confirmed that the developed in-process fuzzy control system is effective for T-shape tube hydroforming.

Increasing the stability of T-shape tube hydroforming process under stochastic framework

Metal forming processes present several sources of uncertainties coming from material properties, geometric characteristics, and loading paths. During the manufacturing phase, such parameters may vary affecting the process stability and increasing the defect parts. Stochastic framework seems more pertinent than classical deterministic approaches to treat such problems since it is intended to include variabilities at the early design stage. In the present work, tube hydroforming process widely used in various industry applications is investigated. To ensure the process stability, loading paths should be optimized with taking into account randomness associated to the input parameters. To control the potential failure modes, the Forming Limit Stress Diagram is implemented in the finite element code to avoid necking while a simple geometrical criterion is defined for wrinkling. A global sensitivity analysis using the variance-based method is done which shows that the selected random parameters impact considerably the variance of failure indicators. Then, a numerical example of T-shape tube hydroforming process is proposed to show the efficiency of the stochastic framework. Statistical and probabilistic observations of the optimum solution show that the stochastic approach yields to an optimum less sensitive to such fluctuations which improves the process stability and minimizes considerably the percentage of defect parts in a mass production environment.

Investigation on the Effect of Pulsating Pressure on Tube-Hydroforming Process

Tube hydroforming process is one of the metal forming processes which uses internal pressure and axial feeding simultaneously to form a tube into the die cavity shape. This process has some advantages such as weight reduction, more strength and better integration of produced parts. In this study, T-shape tube hydroforming was analyzed by experimental and finite element methods. In Experimental method the pulsating pressure technique without counterpunch was used; so that the internal pressure was increased up to a maximum, the axial feeding was then stopped. Consequently, the pressure decreased to a minimum. The sequence was repeated until the part formed to its final shape. The finite element model was also established to compare the experimental results with the FE model. It is shown that the pulsating pressure improves the process in terms of maximum protrusion height obtained. Counterpunch was eliminated as being unnecessary. The results of simulation including thickness distribution and protrusion height were compared to the part produced experimentally. The result of modeling is in good agreement with the experiment. The paper describes the methodology and gives the results of both experiment and modeling.

Influence of Process Parameters on T-Shape Tube HydroForming Characteristics for Magnesium Alloy

Due to the light weight and electromagnetic interference shielding capabilities in magnesium alloy material, it is widely utilized in 3C electronic components and automobile parts. However, its formability is very poor due to the phenomenon of negative strain hardening rate appearing as the deformation in large strain range, so it is usually formed as die casting or casting styles leads to much scrap, and manufacturing cost is thus increased. The objective of this study is to investigate the effect of process parameters on T-shape tube hydro-forming characteristics for magnesium alloy and it may offer the data resulting from the analysis to predict an acceptable product of tube fitting for magnesium alloy forming in industry. AZ31 magnesium alloy tube is used as the billet material for hydro-forming with hydraulic pressure as the main forming power combined with the mechanical auxiliary force from the punch to fabricate the T-shape tubing products. Finite element code DEFORM-3D is adopted to investigate the forming states of T-shape tube forming, by changing process parameters; such as punch velocity, hydraulic pressure, fillet radius of the die and tool-workpiece interface friction etc. to investigate the material flow of tube fitting, wall thickness variations, and stress and strain distributions. By qualifying the forming processes whether if it is completed or not, and synthesizing the overall analysis and judgment, we establish an admissible level of process parameter range for complete tube manufacture. The results show that suitable mechanical force can help material flow, prevent large strain deformation falling into the area of negative strain hardening rate, enhance magnesium alloy to become easy in forming and make tube fitting to be formed successfully.