Deformation Of Tube Research Articles

Cushioning energy absorption of regular polygonal paper corrugation tubes under axial drop impact

Abstract The paper corrugation tube is an attractive and innovative mode of cushioning protection and energy absorption for the general protection and packaging technology of military and civil products. The aims of this paper focus on the dynamic compression characteristics of four kinds of regular polygonal paper corrugation tubes under the conditions of axial drop impacts, and the influence rules of structural parameters and load parameters on the dynamic cushioning energy absorption. The results show that, the tube direction has a crucial effect on the deformation mode of the paper corrugation tubes, the deformation of X-direction paper corrugation tubes has a stable accordion mode, but that of Y-direction paper corrugation tubes is a mixture of steady progressive buckling and other non-ideal modes. The X-direction paper corrugation tubes have lower peak stress, stable and controllable deformation mode with multiple folds, and higher total energy absorption, unit area energy absorption, specific energy absorption and stroke efficiency than the Y-direction paper corrugation tubes. Moreover, the change of cross-section shape of X-direction paper corrugation tubes has no obvious influence on the total energy absorption, while the total energy absorption of Y-direction paper corrugation tube obviously rises with the increase of the number of cross-section edges of the tubes, but the unit area energy absorption, specific energy absorption and stroke efficiency decrease with the increase of the number of cross-section edges of the tubes. Moreover, the increase of the number of cross-section edges of the tubes made the total energy absorption of Y-direction tubes rise, while the total energy absorption of X-direction tubes has no obvious change. But the unit area energy absorption, specific energy absorption and stroke efficiency decrease with the increase of the number of cross-section edges of the tubes. Furthermore, the tube length, impact block mass and impact energy have also important influence on the cushioning energy absorption of the paper corrugation tubes under axial drop impact.

Deformation and energy absorption properties of cenosphere-aluminum syntactic foam-filled tubes under axial compression

The cenosphere-aluminum syntactic foam-filled tubes were prepared by inserting aluminum matrix syntactic foam which is reinforced with cenospheres whose average particle sizes are different (150 μm, 200 μm and 300 μm) into empty steel tubes. Quasi-static axial compression tests were conducted on empty steel tubes, cenosphere-aluminum syntactic foam filler and cenosphere-aluminum syntactic foam-filled tubes. Based on the experimental results, numerical simulation was carried out to investigate the effects of the thickness of the tube wall and the type of filler on crushing behaviour of cenosphere-aluminum syntactic foam-filled tubes. It has been shown that the tube wall can effectively restrain the syntactic foam filler and improve the plastic deformation ability of the specimen. In addition, the interaction between the two can significantly improve the bearing capacity of the foam-filled tube. The height of the specimen has little effect on its peak stress, while a large height-to-diameter ratio may cause instability, which is not conducive to the energy absorption of the specimen. The increase of the tube wall thickness is beneficial to increase the specific energy absorption of the foam-filled tube.

Cross section deformation of heterogeneous rectangular welded tube in rotary draw bending considering different yield criteria

Heterogeneous rectangular welded tube has serious anisotropy of parent metal and weld zone, in order to improve the prediction accuracy of cross-section deformation of tube in rotary draw bending (RDB), it is necessary to select the appropriate yield criterion to describe the anisotropic characteristics of heterogeneous rectangular welded tube. So the anisotropic parameters of Hill’48 and Barlat’89 yield criteria of parent and weld zone were obtained by using the digital image correlation test, then FE models of RDB of rectangular welded tube using different yield criteria were established. Based on these established FE models, the cross section deformation of thin-walled heterogeneous rectangular welded tube in RDB considering different yield criteria was researched. The results showed that, for the height and width deformation ratio of rectangular welded tube, the simulated results obtained by Mises, Barlat’89 and Hill’48 yield criteria in sequence, gradually increased to experimental results, this indicated that Hill’48 can well describe the anisotropic characteristic of rectangular welded tube. Further, under the condition of different bending angles and different core numbers, the maximum height deformation ratio obtained by Mises, Barlat’89 and Hill’48, successively, gradually increased to experimental results, which meant that Hill’48 anisotropic yield criterion was the most suitable one to predict cross section deformation of QSTE700 rectangular welded tube in RDB.

Investigation on the Behavior of κ -Carrageenan Hydrogels for Compressive Intra-Vessel Disintegration.

Gel disintegration via compression is a possible approach for the reversal of the occlusion of male vasa deferentia (VD) by hydrogels. κ -carrageenan (KC) hydrogels can be used for such an application. To determine the required forces for in-vessel compressive disintegration, a gel-tube model, preparing KC gels in different tubes, is studied. These gels are of alternating biopolymer (1-3% by mass) and potassium (100-300mM) concentration. Gel-filled tubes are uniaxially compressed at two different compression speeds (1 and 0.3mm s-1 ). Breakage compression strains are cross studied by shear breaking gel measurements using dynamic mechanical analysis. The measurements showed good agreement. Gel structure disintegration occurred below (62±8) % strain. During compression, three stages of gel disintegration are present. Gel-tube wall detachment, gel rupture, and gel expulsion. The force required for gel disintegration and tube deformation can be added arithmetically. From the modulus of a human aortae model, it is estimated that average human pinch forces are insufficient to disintegrate 2% and 3% by mass KC hydrogels in VD by massage. The compressive disintegration would require a compression device while evading tissue damage.

Experimental investigation on the damage effect of 6063-T5 aluminum alloy circular tubes subjected to blast after exposure to fire

There is a potential risk that the metal tube structures would suffer the combined actions of external fire loads and blast loads during their service life. In this study, the damage effects of 6063-T5 aluminum alloy circular tubes with different wall thicknesses subjected to blast after exposure to natural fire were experimentally investigated. With a special experimental device platform designed, the explosive loading in a very short interval after fire was realized. The deformation and damage of the circular tubes were quantified, and the characteristics of four failure modes were analyzed. The effects of fire duration, stand-off distance and wall thickness on the deformation and damage of circular tubes were quantitatively studied by introducing energy ratio and flattening parameter. The results show that the increase of fire duration and the decrease of stand-off distance or wall thickness could obviously aggravate the damage degree of the circular tube, while the energy absorbed by plastic deformation area and flattening parameter basically increase. By using surface fitting, the functional relation of the temperature and the scaled distance to the global deflection of the tube was obtained. In addition, the variation trend of the deformation parameters was constant in the case of no fracture. Once the fracture occurs, the variation trend of some deformation parameters would be affected.

Method of Predicting Necking True Stress in a Thin-Walled Tube Under a Complex Stress State

Abstract Method of predicting the strength of thin-walled tubes under a complex stress state, taking into account changes in the initial dimensions, is proposed. Uniform plastic deformation of a thin-walled tube under short-term static load by internal pressure and axial tension is considered. The tube material is considered to be homogeneous, isotropic and incompressible. The principle of maximum load is used to derive analytical dependences. The main decisions and conclusions were made using the Considere scheme.

Transient compressible flow in a compliant viscoelastic tube

Motivated by problems arising in the pneumatic actuation of controllers for micro-electromechanical systems, labs-on-a-chip or biomimetic soft robots, and the study of microrheology of both gases and soft solids, we analyze the transient fluid–structure interactions (FSIs) between a viscoelastic tube conveying compressible flow at low Reynolds number. We express the density of the fluid as a linear function of the pressure, and we use the lubrication approximation to further simplify the fluid dynamics problem. On the other hand, the structural mechanics is governed by a modified Donnell shell theory accounting for Kelvin–Voigt-type linearly viscoelastic mechanical response. The fluid and structural mechanics problems are coupled through the tube’s radial deformation and the hydrodynamic pressure. For small compressibility numbers and weak coupling, the equations are solved analytically via a perturbation expansion. Three illustrative problems are analyzed. First, we obtain exact (but implicit) solutions for the pressure for steady flow conditions. Second, we solve the transient problem of impulsive pressurization of the tube’s inlet. Third, we analyze the transient response to an oscillatory inlet pressure. We show that an oscillatory inlet pressure leads to acoustic streaming in the tube, attributed to the nonlinear pressure gradient induced by the interplay of FSI and compressibility. Furthermore, we demonstrate an enhancement in the volumetric flow rate due to FSI coupling. The hydrodynamic pressure oscillations are shown to exhibit a low-pass frequency response (when averaging over the period of oscillations), while the frequency response of the tube deformation is similar to that of a bandpass filter.

Finite Element Modeling of Electromagnetic Crimping of Cu-SS Tube-to-Tube Joint Along With Simulation of Destructive Testing for Strength Prediction of the Joint

Abstract This work explores the tube-to-tube joining of copper (outer) and stainless steel (inner) using electromagnetic crimping. Stand-off distance is kept constant during all the experiments. ls-dynaTM electromagnetic module, which utilizes finite element method combined with the boundary element method, is used to perform numerical simulations and the model is validated with experimentally observed thinning and radial deformation of the outer tube during electromagnetic crimping. Effect of slit of the field shaper on Lorentz force distribution is studied. It is observed that the slit of the field shaper leads to uneven radial deformation. Furthermore, a novel finite element model has been developed to predict the pull-out and compressive strength of the joint. Results are validated with the experimentally observed data.

Free Vibration Analysis of Shear Deformable Small-Scale Tubes

This study presents an approach for investigating free vibration problem of small-scale tubes based on modified couple stress theory in conjunction with higher order shear deformation tube model. The size effect is captured through utilization of a length scale parameter involved in modified couple stress theory. A newly developed refined tube model is employed to satisfy friction-free conditions on inner and outer surfaces of micro-tubes. Hamilton’s principle is used as a variational technique for derivation of governing system of equations. For axial vibrations, an analytical procedure is conducted, while for transverse vibrations differential quadrature method is used as a numerical technique. The correctness of numerical results are verified through comparisons made with results which are available in the literature for limiting cases. The analyses reveal the effects of size and transverse shear deformation on the natural frequencies of micro-tubes.

Creep deformation and rupture behaviour of service-exposed Super304H steel boiler tubes

ABSTRACT The determination of creep properties of the components operating at high temperatures in thermal power plants is an enormous concern for safe life assessment. In this study, a series of miniature creep and tension tests were carried out with service-exposed (54,750 h and 68,550 h at 650 °C) and virgin Super304H steel materials. The power law creep behaviour, creep rupture life, and tensile properties were compared among the virgin and service-exposed materials. The creep strength of the 54,750-h-serviced material was comparable to that of the virgin material, while it decreased significantly for the 68,550-h-serviced material. The degradation of the properties of the service-exposed material was discussed based on metallurgical analyses and precipitation mechanisms.

The effect of decarburisation on creep deformation: application to magnesium reduction steel retort tubes

ABSTRACT This paper studies high-temperature creep deformation of Mg retort tubes considering the decarburisation of steel. A material model was developed for finite element modelling that relates the activation energy of steel in the steady-state creep rate equation (Q) to its carbon content. Carbon content was described as a function of radial position along the retort thickness (r) and service time (t). The time-dependent activation energy, Q(C(r,t)), was incorporated in the steady-state creep equation. The FEM results of the decarburising model were compared to those of the non-decarburising model and an actually failed retort for verification. The newly developed model presents more accurate results compared to the constant material model (non-decarburising). The FE model was used to predict the effects of various process parameters (temperature, internal pressure, and furnace carbon activity) and geometric parameters (retort diameter and thickness) on the creep deformation of retorts.

Crashworthiness study of circular tubes subjected to radial extrusion under quasi-static loading

A structure of circular tubes subjected to radial extrusion with variable geometrical configurations was analysed. In a quasi-static experiment, axial grooves were produced on the circular aluminium tube under the action of indenters, without buckling instability. The energy was absorbed by plastic deformation of the aluminium tube and friction between parts. Deformation and driving force–displacement responses of the circular tube were analysed by way of numerical simulation, which matched the experimental results. Based on the validated finite element (FE) model, the effects of different geometrical configurations on structural crashworthiness were analysed. The results showed that, throughout the deformation stage, a lag was found in force changes in response to the increasing spacing between the aluminium tube and a rib plate and decreasing inclination angle of the indenter. The plastic energy ratio exceeded 60%. The specific energy absorption (SEA) was separately improved by 59.11%, 265.10%, and 75.00% with the increase of the inclination angle and number of the indenters and the decrease of the distance between the indenter and the centre of the tube. The increase in width of the rib plate could not significantly enhance energy absorption effects in the structure. In addition, by utilising the complex proportional assessment (COPRAS) method, it was found that the aluminium tube T3.5 (with wall thickness T of 3.5 mm) exhibited the optimal structural configuration and the best crashworthiness. In conclusion, the use of thin-walled tubes subjected to radial extrusion provide a reference for the development of new energy absorbers.

Deformation and Long-Term Strength of a Thick-Walled Tube of a Physically Non-Linear Viscoelastic Material under Constant Pressure

Deformation and Long-Term Strength of a Thick-Walled Tube of a Physically Non-Linear Viscoelastic Material under Constant Pressure

In-situ deformation measurement of Zircaloy-4 cladding tube under various transient heating conditions using optical image analysis

In a loss of coolant accident (LOCA), fuel cladding deformation is an important factor in terms of maintaining coolable geometry. In order to simulate the cladding deformation behavior, experimental research and the development of a fuel performance code have been conducted. In addition, relevant experimental data concerning the major phenomena for validating the developed code are required. Therefore, in this study, an experimental apparatus named ‘DIMAT’ (Deformation In-situ Measurement Apparatus by image-analysis Technique) is developed to produce high temperature cladding tube deformation data. In order to simulate various accident conditions, an infrared (IR) furnace and pressure injection equipment were assembled. Additionally, the cladding specimen in the IR furnace was clearly recorded by application of high temperature resistant black spray paint and modification of a quartz tube. Some uncertainty factors that might arise due to the paint application were considered and evaluated. After the deformation behavior in a scenario was recorded, the in-situ hoop strain of the cladding was calculated through the developed image analysis method. To ensure accuracy of the established image analysis system, a validation experiment and uncertainty evaluation were performed. Finally, the burst experiments were carried out at low and high heating rates of 1, 14, and 28 °C/s, and consequently the in-situ high temperature strain rate was successfully measured in each experimental case.

Investigation of punch shape design in tube hydro-piercing processes

This study is focused on punch shape design in tube hydro-piercing processes of SPFC590Y carbon steel tubes. The flow stresses of the carbon steel tubes obtained by tensile tests are used in the finite element simulations of tube hydro-piercing process with software “Deform 3D.” The ductile fracture criterion of Normalized Cockcroft and Latham is used during the FE simulations. The critical damage value for NCL fracture criterion is obtained by comparing simulation results and tensile test results. The effects of various parameters such as punch strokes, internal pressures, etc. on tube deformation and fracture mechanism in hydro-piercing processes are investigated. Hydro-piercing experiments are conducted. The characteristics of the experimentally pierced hole sections are compared with the simulation results to validate the analytical models. The effects of various parameters on the characteristics of pierced hole sections after hydro-piercing processes are discussed numerically and experimentally.

Effect of pulse width of middle-coil current on deformation behavior in electromagnetic tube forming under two-stage coils system

In the majority of electromagnetic tube forming system, the distribution of Lorentz force acting on tube is restricted and has poor controllability, which leads to the tube being unable to meet the requirement of manufacturing flexibly. A new electromagnetic tube-forming method based on the two-stage coils system, which consists of two coils and two independent capacitor banks, has been proposed to improve the distribution mode and controllability of Lorentz force. With higher deformation depth and less occurrence of cracking compared with the conventional one single-coil system; this method has been proved to be effective in improving the deformation behavior of tube in electromagnetic forming through experiments. However, the deformation behavior of tube in this forming method still needs further studies. In this paper, the effect of pulse width of middle-coil current on AA1060 aluminum tube deformation behavior under two-stage coil system is investigated through simulation model, which is based on the combination of current filament method and finite element method. Results show that the short pulse width of the middle-coil current can achieve larger deformation depth of tube under relatively small discharging energy, and the long pulse width of the middle-coil current has good performance in deformed profile. Moreover, the thickness reduction in the case of long pulse width of middle-coil current is less than the case of short pulse width of the middle-coil current under equal deformation depth of tube.

Macromolecular Phase-Transition-Driven Motility of Hollow Hydrogel Tubes

The research emphasis and novelty of this work focus on the phase-transition effects on the structural deformation of hollow hydrogel tubes in an aqueous system, where the cross-linking poly(N-isop...

Effect of different errors on deformation and thermal stress of absorber tube in solar parabolic trough collector

Solar parabolic trough collector (PTC) always operates under non-designed conditions in actual situation. Some errors such as slope error, tracking error and installation error strongly affect the absorber tube's deformation and thermal stress performance. Based on the optical-thermal-stress coupling principle, a numerical analysis on the influence of different errors on deformation and thermal stress of absorber tube was carried out by coupling MCRT-FVM-FEM. The results show that the maximum deflection always occurs in the middle of absorber tube, and lower slope error and higher positive y-direction (vertical direction) installation error can greatly increase the deflection of absorber tube. Tracking error and x-direction (horizontal direction) installation error have little impact on the maximum deflection, but can remarkably increase the maximum equivalent stress as slope error is 0 mrad. Due to the occurrence of tracking error and x-direction installation error, the absorber tube's bending direction changes and it's equivalent stress distribution becomes asymmetric. The maximum equivalent stress descends with enlarged tracking error when slope error is greater than 3 mrad. While slope error is more than 6 mrad, the maximum equivalent stress is hardly affected by x-direction installation error. Under the condition of slope error, increasing y-direction installation error from 0 mm to 15 mm elevates the maximum equivalent stress.

Discrete element method using cohesive plastic beam for modeling elasto-plastic deformation of ductile materials

This paper introduces a three-dimensional (3D) simulation to model the elasto-plastic deformation of ductile materials by discrete element method (DEM) using cohesive plastic beam approach. The Euler–Bernoulli beam theory is applied to calculate force and torque reactions of the cohesive beam bond that can account for plastic strain. In order to simulate the elasto-plastic behavior of materials, a coupled model of plasticity and damage is proposed for the cohesive beam bond. The von Mises yield criterion, a modified perfectly plastic law and an exponential damage law are implemented to simulate behaviors of ductile materials such as steel and aluminum in tensile tests. It is then further applied to investigate the ductile fracture modes such as localized shear fracture and necking phenomenon with cup-and-cone shape. Finally, the proposed DEM model using cohesive plastic beam is applied to visualize the compression test of cylindrical steel sample and wrinkle deformation of steel tube under bucking due to axial compression. This paper is the first attempt to model ductile materials by DEM with cohesive beam bond in tension, compression and buckling. All of the numerical benchmarks demonstrate the power of DEM using cohesive beam bond to model ductile materials with fracture, large deformation and elasto-plastic behavior.

Experimental study on the crashworthiness of bio-inspired aluminum foam-filled tubes under axial compression loading

As a lightweight and efficient energy-absorbing structure, thin-walled filled structure is widely used in various fields. This paper proposed four types of bio-inspired foam-filled thin-walled structures based on two typical straw structures (Cornstalk and Reed): bionic foam core with a central hole, 4 square holes, 4 taper holes and 2 nodes, respectively. The energy absorption capacity and deformation mode of bionic structures were studied by dynamic drop hammer and quasi-static compression. The results showed that 9 of 12 bionic samples had higher energy absorption capacity than the corresponding fully-filled samples. Different bionic features have different effects on the deformation of thin-walled tube, and the bionic features with the best overall performance are the 4 Square Holes and 4 Taper Holes design. It is noted that the bionic method can improve energy absorption capacity and affect the deformation mode of the thin-walled tubes under certain conditions.