Outer Side Research Articles

Pengaruh Penambahan Natural Rubber Pada Ban Dalam Dengan Metode Presure

The inner tube determines the effectiveness and efficiency of a commercial transportation vehicle, where the inner tube is expected to have high durability against friction with the outer tire and to have high tensile stress when holding a heavy load. To answer this condition, the process of adding natural rubber material to the inner tube was carried out using the pressure method with 2 variables, namely one layer of inner tube and one layer of natural rubber which was affixed to the outer side of the inner tube, as well as one inner tube with two layers of natural rubber located on the side outside and inside on the inner tube. Then the testing process is carried out, namely tensile brake and hardness to obtain data to determine the effect of adding natural rubber to the inner tube using the pressure method as one of the references for producing better inner tubes. After the research process was carried out, the results of the tensile brake test were 20.4 Kgf on the first specimen, 23.8 Kgf on the second specimen, 31.05 on the third specimen. Furthermore, from the hardness test, a result was obtained, namely 52° on the first specimen, 48° on the second specimen, 44° on the third specimen.

Laser-driven electrodynamic implosion of fast ions in a thin shell

Collision of laser-driven subrelativistic high-density ion flows provides a way to create extremely compressed ion conglomerates and study their properties. This paper presents a theoretical study of the electrodynamic implosion of ions inside a hollow spherical or cylindrical shell irradiated by femtosecond petawatt laser pulses. We propose to apply a very effective mechanism for ion acceleration in a self-consistent field with strong charge separation, based on the oscillation of laser-accelerated fast electrons in this field near the thin shell. Fast electrons are generated on the outer side of the shell under irradiation by the intense laser pulses. It is shown that ions, in particular protons, may be accelerated at the implosion stage to energies of tens and hundreds of MeV when a sub-micrometer shell is irradiated by femtosecond laser pulses with an intensity of 1021–1023 W cm−2.

A Design Study on HTS Halbach Array for Field Coil of 40 MW Ship Propulsion Motor

A 40 MW ship propulsion motor was designed with a high temperature superconductor coil Halbach array. The Halbach array was applied to the field coil of the motor for further performance improvement. We performed our design study on two different motor types: Halbach array inner positioned field coil motor (HIFM) and Halbach array outer positioned field coil motor (HOFM). The design for the field coil was optimized with NSGA-II. Final models were selected for HIFM and HOFM, respectively, and to estimate the effect of the HTS coil Halbach array, they were compared with reference motors with a conventional field coil. Both HIFM and HOFM showed a 7% increase in the flux to the air-gap. As the shielding effect of the Halbach array in HOFM reduced by 70% the weight of the iron shield, HOFM showed comparable weight compared to the conventional inner field coil motor. This overcomes the problem of the low power density of the outer field coil motor. With the Halbach array field coil, a design topology having the stationary field coil on the outer side of the motor would be realized with a simplified cooling structure while maintaining the light shield weight.

Investigation on a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells

High-precision and high-purity acquisition of tumor cells from whole blood is vital for early disease detection and diagnosis. Here, we investigated a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells (CTCs) from the blood through numerical methods. We introduced a spiral microfluidics channel in the first stage (1st) for cell focusing and rough sorting to improve chip integration and reduce the dependence on sheath flow and extra syringe pumps. In the 1st, we simulated the spiral microfluidic with a rectangular cross section to determine the key parameters affecting the migration kinetics of blood cells and tumor cells. Under the influence of Dean drag force and inertial lift force, blood cells migrate toward the inner side of the channel, while CTCs flow out close to the outer side. A flow rate of 400 μl/min was optimized for the operating flow rate. To improve and further enhance the 1st sorting efficiency and purity, we introduced tilted angle standing surface acoustic wave (SSAW) in the second stage (2st). Based on the parametric study, the SSAW with 33.3 MHz, tilted angle with 5°, and acoustic pressure amplitude with 0.7 MPa was selected as the operating parameter. The product of the 1st is used as input for the 2st acoustofluidic unit, enabling a more accurate separation process to obtain CTCs. The simulation results show that the inertial microfluidic units arranged in the first stage help to improve throughput and assist in 2st acoustofluidic separation, and the cascaded chip has accomplished a separation performance of nearly 100% in terms of purity and efficiency.

Assessment of chemo-mechanical degradation of concrete sewer pipes through an integrated experimental approach

The chemo-mechanical degradation of unreinforced concrete sewer pipes applied in domestic service locations is assessed through a systematic, integrated experimental approach, considering 18 new and 35 used sewer pipes. The characteristics and environmental conditions of the sewer pipes are reported, and data obtained from surface condition classification, residual alkalinity tests and XRD analyses are combined to identify the type and degree of chemical attack of the used sewer pipes. Concrete material properties are determined by material tests on sewer pipe samples, providing quantitative insight into the age dependency of the Young’s modulus, compressive strength, tensile strength and mode I toughness. All relatively old pipes (installed in the 1920s and 1950s) show substantial chemical attack by biogenic sulphide corrosion (at the inner side of the pipe) and carbonation (at the outer side of the pipe). The time development of the corresponding corrosion depths on average follows a linear trend, whereby the corrosion rate for biogenic sulphide corrosion is about a factor of 1.3 larger than for carbonation. Due to these chemical processes, the mechanical properties of concrete may significantly depend on the age of the sewer pipe. In particular, the average compressive strength and average tensile strength decrease approximately linearly with the age of the pipe, in correspondence with relative reductions of, respectively, a factor of 1.7 and 1.5 over a period of almost 100 years. The values and time-dependent trends found for the concrete properties and corrosion depths of sewer pipes can serve as input for practical analyses and advanced numerical simulations on their bearing capacity and time-dependent degradation. The experimental results also emphasize the importance of regularly assessing the amount of chemical degradation of (especially older) in-situ sewer pipes, by determining the (decrease in) effective wall thickness via core sampling and laser profiling.

Application of Digital Twin in the Industry of Axial Hollow-Wall Pipes

With the increasing demand for automation in agriculture, more and more researchers are exploring the application of digital twin in agricultural production. However, existing studies have predominantly focused on enhancing resource utilization efficiency and improving irrigation control systems in agricultural production through the implementation of digital twins. Unfortunately, there is a noticeable research gap when it comes to applying digital twins specifically to buried water conveyance pipelines within an agricultural irrigation infrastructure. Focusing on the long-term performance requirements of buried pipelines in agricultural irrigation and drainage, this study established a digital twin system for the industry of axial hollow-wall pipes with an outer diameter of 200 mm, specifically designed for this field of operation. The system was used to optimize the end-forming process of axial hollow-wall pipes, resulting in improved leak tightness under internal pressure and angular deflection of the pipes. The study suggests that the most effective method for the end-forming process of axial hollow-wall pipes is to heat the pipe for 60 s at the ambient temperature of 15 °C, with heating temperatures of 225 °C on both the inner and outer sides. Additionally, preheating the stamping equipment to 70 °C and controlling the cooling temperature, during pipe detachment, to between 35 °C and 45 °C is recommended. In terms of the leak tightness under internal pressure and angular deviation, the study found that increasing the thickness of the protruding end of the sealing ring to 16 mm, and shortening the chamfer length to 20 mm, while maintaining the same slope, can enhance the sealing effectiveness of the pipeline interface. The implementation of the digital twin system improves the production efficiency of the hollow pipe production line during the end-forming process, resulting in a yield rate of the pipe of up to 95% for qualified products. Moreover, the system provides intelligent closed-loop feedback which ensures the long-term operation and maintenance of the pipelines, making it easier to identify problems and implement design improvements. By doing so, it contributes to ensuring the long-term stability of related agricultural production.

Moisture regime of enclosure structures with insulation layer in educational buildings

AbstractAn assessment of the moisture regime of the external enclosing structures of the building with a layer of insulation on the outer and inner sides was carried out, considering the thermophysical characteristics of all materials of the outer wall of the building. It is shown that brickwork without insulation to preserve the estimated term of its optimal operation, requires taking measures to bring its thermal resistance to heat transfer to a standardized value or to arrange more intensive air exchange in the premises of the building. It has been proven that when designing residential and public buildings, the results of assessing the moisture regime of external enclosing structures and the building's energy indicators for compliance with current requirements are a very important criterion.

Monitoring and Analysis of the Collapse Process in Blasting Demolition of Tall Reinforced Concrete Chimneys.

Aiming at the problem of displacement of collapse direction caused by the impact of the high-rise reinforced concrete chimney in the process of blasting demolition, combined with the monitoring methods such as high-speed photography observation, piezoelectric ceramic sensor, and blasting vibration monitor, the impact process of the 180 m high chimney was comprehensively analyzed. The results show that the chimney will experience multiple 'weight loss' and 'overweight' effects during the sit-down process, inducing compressive stress waves in the chimney. When the sit-down displacement is large, the broken reinforced concrete at the bottom can play a significant buffering effect, and the 'overweight' effect gradually weakens until the sit-down stops. The stress of the inner and outer sides of the chimney wall is obviously different in the process of collapsing and touching the ground. The waveform of the monitoring point of the piezoelectric ceramic sensor is divided into three stages, which specifically characterizes the evolution process of the explosion load and the impact of the chimney. The vibration induced by explosive explosion is mainly high-frequency vibration above 50 Hz, the vibration induced by chimney collapse is mainly low-frequency vibration below 10 Hz, and the vibration characteristics are obviously different. In the process of blasting demolition and collapse of high-rise reinforced concrete chimney, due to the impact of sitting down, the wall of the support tube is subjected to uneven force, resulting in the deviation of the collapse direction. In practical engineering, the control measures of chimney impact, blasting vibration, and collapse touchdown vibration should be fully strengthened to ensure the safety of the protection target around the blasting demolition object.

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou, China.

A new species, Sinocyclocheilus xingyiensis, is described based on specimens collected from a karst cave in Guizhou Province, China. The authors used an integrated taxonomic approach, including morphological and molecular data, to identify the new species as a member of the Sinocyclocheilu angularis group, and it can be distinguished from all other members of this group by a combination of the following features: two pairs of long barbels and long pectoral fins, 42-46 lateral-line scales, 7 (13-14) on outer (inner) side of the first gill arch and 35 (14-15 + 4 + 16 - 17) vertebrae. Phylogenetic analyses based on the cytochrome b (cyt b) gene fragment suggest that S. xingyiensis is a sister lineage to Sinocyclocheilus flexuosdorsalis. The genetic distance (Kimura 2-parameter) between the S. xingyiensis and S. angularis groups of Sinocyclocheilus species based on cyt b gene fragment ranged from 1.2% to 15.4%.

Development of microstructural heterogeneities and dynamic restoration activity during ring rolling of Ti-6Al-4V alloy and its tensile response

Ring rolling is one of the advanced metal forming processes to produce seamless rings. Being a bulk forming process, inhomogeneity in the distribution of strain and temperature can be anticipated in the ring cross-sections. This, in turn, is expected to influence the evolution of microstructure and correspondingly the mechanical properties. Processing of Ti‐6Al‐4V alloy is equally challenging because of its poor thermal conductivity and formability with a limited deformation window. Ti‐6Al‐4V preforms were rolled at elevated temperature under two different main roll feed rates to obtain approximately 30 % deformation in the lab scale ring rolling facility. The evolution of microstructure, including crystallographic texture, was examined as a function of feed rate at different locations of the rings using electron backscattered diffraction (EBSD) technique, and subsequently the tensile response of the rings at selected locations was evaluated at room temperature. The effect of feed rate was found to be marginal on the microstructure evolution; however, there were substantial differences in grain sizes and texture evolution in the regions from inner to outer side of the ring cross-section. Coarse grains were seen at centre region of the ring, while fine grains were present in the region near inner diameter of the ring. Surface regions which experienced more deformation developed basal texture, while the interior regions possessed shear texture after ring rolling. Detailed analysis of the EBSD results suggested orientation dependent continuous dynamic recrystallization as the restoration mechanism in the alloy during ring rolling. The effect of feed rate on the tensile response of the ring rolled alloy was found to be negligible; however, the tensile strength of the ring varied with the location, in accordance with the microstructural heterogeneity. This study provides proper basis for quality control and better understanding for technical guidance required for designing the ring rolling process, specifically for Ti‐6Al‐4V alloy.

Design of an Enhanced Isolation 8-Unit MIMO Antenna for Smartphones Operating in 5G nR and LTE 42 Bands

A miniaturized enhanced isolation 8-unit MIMO antenna for smartphones is proposed in this paper. The units are planar inverted-F antennas with the same structure, and we use the slotting method and shorted probe to miniaturize them. The size of every unit is 14 × 6 mm2 (0.149 × 0.064λ2). We insert an L-shaped decoupling element into the middle of adjacent radiating elements and connect the decoupling element to the GND. Note that the decoupling elements are on the outer side of the substrate, and the radiating elements are on the inner side of the substrate. Finally, a prototype is fabricated and measured. The measured results show that the bandwidth of the MIMO antenna is from 3.0 GHz to 5.3 GHz (55.4%), which fully supports the n77, n78, and n79 in the 5G nR frequency band and the 4G LTE 42 frequency band (S11 less than −6 dB). The measured isolation of the MIMO antenna is greater than 25 dB by using the decoupling method in this paper. The envelope correlation coefficient of the proposed MIMO antenna is less than 0.08, its radiation efficiency is greater than 50%, and its gain is between 4.2 and 5.3 dBi in the whole operating frequency band.

MODERN METHOD OF APPLYING THE MIXTURE ON A VERTICAL SURFACE

When applying mixtures to a vertical surface, it is not always possible to use stationary equipment. This includes scaffolding, cradles, aerial work platforms, and, for small volumes, installation climbers. The mixture is usually applied with a roller, brush or spray gun. These methods lead to excessive consumption of the mixture, increased work time, and often a lack of safety precautions. Working at height is very dangerous, especially in the current environment. Therefore, both in our country and abroad, scientists are developing new alternatives to manual, semi-manual and mechanised methods. One of these mechanisms is automation and robotics. The task of the workers is to control the work processes, monitor the supply of materials and replace equipment as necessary. Such mechanisms are operated by up to three workers. Having studied all the available information, the authors proposed to use the Portal equipment to perform a range of works at height. It will allow you to perform work on slopes, terraces, and hard-to-reach places. To do this, you need to make a small terrace, level the surface, mount the rails, and install the Portal. Then, using additional mechanisms, the equipment is attached. In the first stage, augers are used to drill a well into which the reinforcement is installed, and the concreting process is carried out using various removable devices (winches, drills, etc.) that are attached to the Portal. In the second stage, the ground is excavated, and the pile is exposed by 3.6 metres. In the third stage, a wooden formwork is placed between the piles. The frame is partially attached to the pile, and the outer side of the formwork is mounted. The concreting process is carried out sequentially. First, the lower part is concreted, and then the upper part. In the fourth stage, the mixture is applied to the surface. The article presents and analyses the results of laboratory studies of the operation of the Portal equipment with a device for intensifying the injection of a flowing mixture. The following schemes were considered when choosing the technology of mixture injection: perpendicular-straight-line, perpendicular-circular and inclined-straight-line. The optimal combinations of layer thickness and the angle of inclination of the nozzle axis to the surface and technological schemes of application are given.

Qualitative analyses of thin film-based materials validating new structures of atoms

An X-ray instrument is a paramount technique for analyzing the structures of electronic and crystalline materials. In materials chemistry and physics, discussing the results of X-ray techniques is a routine job. In the thin film, powder, bulk, or another form of material, suitable electronic rings of the atoms forming the top-layered surface experience X-rays. Reflection and inverse reflection of X-rays define the peaks upon interaction with left and right-sided segments of electronic tips constructing suitable rings of atoms. In X-ray analysis, X-rays interact with the north side of the electrons. The X-rays interact with the electrons from the left side when the incidence of X-rays is from the left side. If the 2θ is also less than 90°, the X-ray incidence is from the downward side, so the X-rays get reflected tangentially to the inward sides recording intensity at the position of the detector. When the incidence of X-rays is from the right side, the X-rays interact with the electrons from the right side. As the 2θ is greater than 90°, the X-ray incidence is from the upward side. The X-rays get reflected tangentially mainly to the outer sides, thus not recording intensity at the position of the detector. The present work discusses the X-ray patterns of titanium nitride coating, carbon film rich in nanocrystalline diamond phase, and tantalum carbide film in preliminary detail. In developing electronic or crystalline materials, a primitive cell does not form a basis of a crystal structure. A lattice constant appears to be irrelevant now. The 2θ length between the peaks depends on the distance between the associated electronic rings of atoms. The results of this study agree with the atomic and electronic structure presented under the new insight.

Numerical Investigation of Hydrodynamics in Inline Mixers

The utilization of inline mixers for continuous fluid mixing is a common practice in chemical industries. Information related to hydrodynamics condition in inline mixers is found to be limited while it is crucial for inline mixer type selection. Evaluation of hydrodynamic characteristics in several commercial inline mixers is analyzed in this study, including Y-type, T-type, elbow type, and internal injection mixer types. The analysis is conducted using computational fluid dynamics (CFD) for various Reynolds number conditions from 5,000 to 200,000. Mesh independence tests and model validation with experimental results are performed to ensure simulation accuracy. The CFD results showed that the Y-type mixer type provides the shortest distance i.e., about 12 times diameter. The internal injection type mixer has the most extended hydrodynamic region length to reach a fully-developed region for the same Reynolds number. The highest wall stress is indicated by the injection inline mixer type that located at the outer side wall of the injection pipe. The wall stress at that region is observed to be around twice as large compared to the other mixer type. Meanwhile, the mixer joint in the T-type and Y-type mixers were found to have a wall stress hotspot. Logarithmic correlation formulas were successfully formulated to correlate hydrodynamic region length and Reynolds number for all mixer types. The study results are essential in serving as the basis for inline mixer selection in the industrial sector

Ficussubgen.Spherosukesect.Americanaeser.Dugandii(Moraceae): A Curved Ostiolar Margin Group of Neotropical Fig Trees

Abstract—This work presents the new taxonFicusseriesDugandiicharacterized by the syconium ostiolar margin with wall curved to the outer side of the syconium, forming a short apical tube, irregularly rounded to triangular. For this study, field trips were carried out and collections of herbarium specimens, types, and protologues were analyzed. The series has 15 species with 50 synonyms proposed here, distributed from Mexico and the Antilles to southeastern Brazil. Names likeF. llanensis,F. llewelynii,andF. mitrophora, previously synonymous, are considered correct species names. Lectotypes have been designated forF. acarouaniensis,F. clethrifolia,F. glycicarpa,F. holosericea,F. velutina,Urostigma euomphalum, andU. maximilianum; a neotype forF. frigida; and epitypes forF. holosericeaandF. trigonata.

Anchor Behavior of One-Side Bolt with Flip-Top Collapsible Washer

With the development of blind bolts that can be installed from the outer side of a section, the application of steel pipe hollow sections in prefabricated structures has become possible. The novel one-side bolt with a flip-top collapsible washer (FTW-OSB) is proposed, which can fold the washer at the end of the bolt to achieve a simple and efficient installation. Firstly, the components and installation process of the FTW-OSB are introduced. Additionally, axial tensile tests were carried out on three types of new bolts, and the failure mode, load–displacement curve, and ultimate capacity were analyzed. Based on this, the finite element model was verified, and through a series of finite element parameter analyses, the influence of washer size and construction, the friction coefficient, and the contact surface size on the new bolt were analyzed and optimized. The results show that the L-shaped washer can prevent washer rotation and has better anchoring performance than the I-shaped washer. The washer thickness, height, and upper contact surface size are the key factors affecting the anchoring performance of the FTW-OSB bolt. Among these factors, when the washer thickness increases from 0.1 d0 to 0.3 d0, the ultimate capacity and initial stiffness of the FTW-OSB bolt increase by 136.5% and 100.3%, respectively. The lower contact surface size and friction coefficient can be ignored. The failure model of the FTW-OSB is mainly washer shear failure and bolt tension failure. By effectively adjusting the washer thickness, side wall height, and upper contact surface size, shear failure of the washer can be avoided and an anchoring performance can be achieved that is the same as that of the same type of 10.9-grade ordinary high-strength bolt.

Correlation between cargo properties and train overturning safety for a high-speed freight train under strong winds

The high-speed railway has become an important passenger transport mode. Relying on the abundant passenger transport experience and expansive railway network, the high-speed freight train (HSFT) is feasible to be developed and has great application potential. As a critical component of HSFT, the cargo plays an important role in the overturning safety of HSFT under strong wind conditions. Previous studies about the aerodynamic performance of the high-speed train usually regarded the loaded carbody as an individual rigid body. Limited attention was paid to the variability inside the vehicle. In order to improve the running safety of HSFT under strong wind conditions, the multibody dynamics simulation is adopted to demonstrate the effect of cargo property on the overturning risk of HSFT under the aerodynamic loads obtained through the computational fluid dynamics (CFD) simulations. It is demonstrated that the inner side crosswind is more dangerous than the outer side crosswind. The speed of HSFT should be limited according to the cargo quantity, and the maximum speed for a fully loaded HSFT can be 305 km/h when the crosswind velocity is 20 m/s. The larger cargo density should be encouraged because it is good for train overturning safety in severe working conditions.

Pemetaan Morfologi Ambang Galala Poka (APG)

The Galala Poka (APG) sill is in the form of an underwater hill located in the narrow waters of the TAD and TAL transition zones. The morphology of APG is important to map because it influences the dynamics of water masses during the tidal period in the TAL and TAD Transitional areas, and can even explain the phenomena of cohesive sediment transport and deposition as well as tidal mixing phenomena that often occur around APG. This research aims to map the topographical profile of the APG seabed and calculate its spatial dimensions.The GIS-based mapping method is used to create an APG seabed topographic model using data compiled from sounding results, digital Navionic Sonar Chart data and digital shipping channel bathymetry data. The trapezoidal rule model is used to calculate the APG dimensions. APG seabed 2D and 3D spatial models mapped with ArcGIS 10.8 and Surfer 23.The results of the analysis found the APG boundaries at coordinates 128.19316 – 128.19829E and 3.66027 – 3.56659S and UTM coordinates 410399.1390 ​​– 410969.1292 mT and 9594764.3000 – 9595384.3000 mU. The topography of APG is generally convex with a flat peak at the center. There are variations in the slope of the seabed, especially on the outer side of the APG. APG volume with a reference depth of 0m (LWS) 1,304,828.05 m3, surface area 151,954.65 m2. At a reference depth of 8m, the APG volume is 20,071.95 m3, the area is 94,887.23 m2. At a reference depth of 10m, the APG volume is 351,296.95 m3, and the surface area is 73,012.06 m2.

IMPROVING MANEUVERABILITY OF A WHEELED VEHICLE BY IMPROVING TURN CONTROL METHOD

A large number of scientific works and design developments are devoted to the study and improvement of the properties of maneuverability, which is also a complex (complex) property. At one time, the need to reduce the building volume required the installation of swivel wheels on the front steering axle of the car. However, in this case, additional resistance to the movement of the machine arose, which is due to the discrepancy between the trajectories of the movement of the front outer and inner guide wheels with their trajectories during an ideal turn. The development of the designs of electric vehicles and hybrid vehicles allows for separate control of the front wheels. The analysis of the whole variety of indicators and criteria of maneuverability in general and individual properties was carried out. Unlike other systematization of these indicators and criteria, it is proposed to divide these indicators and criteria into three main groups. All indicators and criteria used to assess the maneuverability of vehicles are also used to assess the maneuverability of wheeled tractors with a center of mass shifted to the rear axle and, therefore, have low controllability. Force and energy criteria can be used in the design of cars and tractors to ensure the ability of the latter to maneuver. In addition, as a result of the study, a combined method for controlling the movement of a two-axle swivel bogie of a wheeled vehicle has been improved due to the fact that its rotation is carried out by two torque control moments. The first of these control torques is generated by the driver through the steering and power cylinder. The second torque control moment is created due to the difference in torques on the wheels of the outer and inner sides of the two-axle swivel bogie. The implementation of these rules for regulating the distribution of traction forces between the sides makes it possible to overcome the resistance to rotation of a two-axle swivel bogie and improve the quality of motion control of the specified bogie and wheeled vehicle. Keywords: maneuverability, separate control, wheeled vehicle, control method, two-axle swivel bogie

Investigation on the wall thickness variation of an eccentric tube in the rotary draw bending process

PurposeWhen bending a large diameter thin-walled tube, the thickn ess of outer side wall will reduce greatly, which leads to a decrease of structural strength of the tube. To solve this problem, this paper investigated the deformation principles of an eccentric tube in the rotary draw bending process, trying to find a way to reduce the wall thickness difference between inner and outer diameters.Design/methodology/approachAn finite element model is established for analyzing the deformation of an eccentric tube in rotary draw bending process. The wall thickness distribution of the formed pipe was analyzed along the axis and diameter, respectively.FindingsIt is found that there exists an optimal eccentricity between the inner and outer circle center of the tube cross-section. If the eccentricity of the tube is chosen properly, it is possible to get a bent tube with equal thickness of inner and outer side walls. In addition, it is also found the optimal eccentricity on the cross-section can be influenced by bending radius, wall thickness, diameter and bending angle. The optimal eccentricity increases greatly with the decreasing of bending radius, the increase of outer diameter and the increase of wall thickness. The influence of bending angle on the optimal eccentricity can be divided into two situations. When the bending angle is small, the optimal eccentricity increases with the increase of bending angle. When the bending angle exceeds a certain value, the pipe enters a stable forming state. The optimal eccentricity of the stable forming region does not change with the bending angle.Originality/valueSuch a research is beneficial for reducing the thickness difference between inner and outer side walls in the rotary draw bending process.