Mandrel Type Research Articles

Manufacturing of flax- and glass-fibre reinforced thin-walled tubes and measuring their interlaminar shear properties by torsion tests

Recently, methods for determining interlaminar shear properties have been continuously developed to achieve homogeneous stress states and avoid edge effects. In this regard, the torsion test on tube specimens represents a setup with many advantages. Therefore, fibre composites made by a winding of glass and flax fibres were produced at a new type of mandrel, resulting in tubes with a wall thickness between 370 µm (glass) and 640 µm (flax). A new method for determining the shear strain is described in the context of the torsion test. The results are in line with analogous investigations, proving the validity of the new methodology.

Design and Flow Field Analysis of a New Mandrel Type Hydraulic Buffer

Design and Flow Field Analysis of a New Mandrel Type Hydraulic Buffer

Numerical and experimental investigation of the thermal and electrical characteristics of a lithium ion cell

In this study, an electrochemical-thermal coupled model was developed to investigate the electrical and thermal behaviors of the commercial NCR18650b Li-ion cell during three different discharge rates. The 1-dimensional electrochemical model consists of a positive electrode, electrolyte, and a negative electrode and employs the related mass and charge transfer equations for both solid and liquid phases predicting the cell's voltage variation. The 3-dimensional thermal model involves a mandrel, an active battery part, and a shell. The thermal model solves the general heat diffusion equation and predicts the temperature variation of the cell. The results show that the predicted temperature-voltage profiles follow the same trend with experimental data and are consistent. The maximum calculated root mean square errors are obtained as 0.11 V for voltage, and 0.96 °C for temperature predictions. On the other hand, the maximum temperature differences within the cell was found to be 0.16 °C, 0.43 °C, and 1.29 °C after the 0.5 C, 1C and 1.5 C rate discharging processes, respectively. Finally, the results from the 3-dimensional thermal model reveal that the type of mandrel affects the temperature variation within the cell. However, the average surface temperature of the cell remains comparable for the investigated C rates.

Deformation behaviors of double-ridged rectangular H96 tube in rotary draw bending under different mandrel types

Cross-sectional deformation is the most important formability assessment factor in rotary draw bending (RDB) of double-ridged rectangular tube (DRRT). Mandrel type influences the cross-sectional deformation directly. Due to the special cross-sectional shape of DRRT, the selection of right mandrel type becomes the most challenging task. Thus, a disconnect-type rigid mandrel and two kinds of PVC elastic mandrel were proposed. The influence of three mandrels proposed on the cross-sectional deformation of DRRT was investigated. The results show that (1) the type I mandrel can control the height deformation of flange preferably and the type III mandrel can control the deformation of distance between outer and inner ridge groove well. With respect to restraining the width deformation of DRRT, the two mandrels have their own merits. The performance of type II mandrel in preventing height deformation of DRRT is too poor to be used as a mandrel. (2) Only the type III mandrel is feasible when the mandrel support range is larger. Increasing the mandrel support range can decrease the height deformation obviously, but it has little effect on the width deformation. (3) When the size of DRRT is smaller, the type III mandrel can be a better option. However, when the size of DRRT increases, the height deformation of flange will increase evidently and the type I mandrel should be a better choice at this time.

A chain link mandrel for rotary draw bending: experimental and finite element study of operation

Rotary draw bending is one of the methods used for bending of thin wall tubes. In this process, the mandrel is positioned inside the tube, and the bend die, clamp die, pressure die, and wiper die surround the tube. The bending is conducted around the bend die. Conventional mandrels are mostly ball link type whose manufacture needs high precision and cost. Links of ball link mandrels are exposed to failure in necking areas due to particular form of the links. In this paper, a new mandrel type called “chain link mandrel” is presented, manufactured, and tested. The main difference of this mandrel with conventional mandrels is in the degrees of freedom of the mandrel’s ball segments. Finite element simulation of the bending process, using proposed mandrel and ball link mandrel, has been conducted in ABAQUS software, and some parameters, including required bending moment for tube bending, tube’s ovality, the variations in tube wall’s thickness, and spring back have been measured and compared between two types of mandrels. The clearance between external surface of the mandrel and internal wall of the tube and other influential process parameters has been set equal in both simulations. The simulation results showed that the amounts of thinning in outer wall of the bend, thickening in inner wall of the bend, tube’s ovality, and spring back are equal for both of mandrels. This fact proves the proposed mandrel’s effectiveness, despite its lower cost and simplicity compared to ball link mandrels. Experimental tests are also carried out, and the findings are compared with those obtained in the finite element simulations. There is good agreement between the simulation and experimental results. Practical operation of the proposed chain link mandrel shows that it has good performance for bending thin wall tubes. This mandrel is less expensive and stronger than the conventional ball link types, and the quality of the tubes bent by using this mandrel is acceptable.

Comparison between the effects of PVC mandrel and mandrel-cores die on the forming quality of bending rectangular H96 tube

A new type of mandrel, which is PVC material and supposed as elastic–plastic deformable part in the simulation, is proposed to use in rotary-draw bending process, due to it can fill the tube entirely. The effect of PVC mandrel on the forming quality of rectangular H96 tube, such as tube damage distribution, wall thickness variation, section deformation, springback, is researched by comparing with the traditional mandrel-cores die. It is found that, the maximum damage value obtained with PVC mandrel is smaller than that with mandrel-cores die. The PVC mandrel leads to a smaller tube thickness variation and a more uniform tube thickness distribution compared with the mandrel-cores, for the PVC mandrel brings about smaller stress in the bending process. The PVC mandrel is recommended to be used in the rotary-draw bending process due to its advantage in the prevention of height deformation, though, the constraint effect on the tube width provided by the PVC mandrel is a little weaker than that by mandrel-cores die. Especially, the PVC mandrel with 1.5 times plastic hardening performs excellent well on the reduction of sectional height deformation of symmetrical line. The springback angle obtained with mandrel-cores die is smaller due to the retracting mandrel process. The PVC mandrel should be taken away from the tube before the springback occurs, which can be realized by heating the mandrel to soft.

Investigation of Deformation Behavior of Ring-Tensile Specimens Machined from Pressure Tubes of Indian PHWR

Specimens machined in the form of circular rings directly from the nuclear reactor pressure tubes and tested in a ring-tension test-setup offer great simplicity in evaluating the transverse mechanical properties of the as-manufactured as well as those of the service-exposed tubes. However, the state of stress in the specimen cross-section is not purely uni-axial due to the effect of bending and the presence of lateral pressure due to the loading mandrel. This requires the use of 3-D finite element (FE) analysis for simulation of deformation behavior of the specimens in the ring-tension test-setup. In this work, we have analyzed the deformation behavior of ring-tension specimens machined from two different types of zirconium alloy pressure tubes as used in the Indian pressurized heavy water reactors. The effect of geometry of the loading mandrel (i.e., 2-piece vs. 3-piece type of mandrel) on the load-deformation behavior of the test-setup has been studied. It was observed that the values of maximum load as well as the deformation behavior in the post-necking region differ significantly when only the geometry of the loading mandrel is changed keeping all the other parameters same. FE analysis has been able to correctly predict these variations as it takes into account of the effect of geometry, material properties as well the interaction between the mandrel and the specimen. Hence, the use of FE method is essential in the inverse analysis procedure where the material properties can be determined from these complex test-setups.

A New Optical Fiber Acoustic Sensor Based on Air Backing Mandrel Type Fiber Optic Hydrophone

We propose and demonstrate an optical fiber acoustic sensor based on air backing mandrel type fiber optic hydrophone. This novel approach to sensing sounds in the air has not been utilized before and has the advantage that the sensor doesn’t need electric power supply when it is working. To prove the feasibility of such an optical fiber acoustic sensor, we make a model and set up experiment to get the acoustic waves response curve in frequency. Because of its simple mechanical structure, the sensor is robust and shows a good application prospect.

Study on the influence of mandrel type on copper tube rotary draw bending

The process of rotary draw bending is a versatile, cost-effective and precise method for thin-walled copper Air Conditioning and Refrigeration (ACR) tube. Requested in industrial application for ACR tube, the wall thinning and the fattening of the cross-section are two major formability assessment factors. Mandrel type influences both of the formability assessment factors directly. In this paper, a 3D elastic-plastic Finite Element Method (FEM) model of the rotary draw bending is established using the dynamic explicit FEM code LS-DYNA. An experiment has been carried out to verify the FEM model. The influences of three basic type of mandrel on stress distribution and sectional deformation during the bending process have been investigated, and role of geometry parameter of complex-surfaced and ball-and-socket mandrel in wall thinning and sectional degradation has been revealed. The results indicate that wall thinning and sectional degradation can be precisely under control by choosing mandrel type and setting key geometry parameters.