Springback Angle Research Articles

Analysis of bending force and springback behavior of metal–polymer–metal sandwich laminates

The bending and springback behaviors of sandwich laminates are more complex than those of monolithic sheet materials because of the differences between the properties of the core and skin materials. In this study, simplified analytical and numerical models were used for analyzing the springback angle and bending force of metal-polymer-metal sandwich laminates under bending. An analytical model was used to predict springback in three-point bending. The springback angles and bending force obtained from the numerical model correlated well with the experimental results. It was found that the finite element model using solid elements in the core was advantageous for predicting the shape after bending. It was demonstrated that these models can be used to design sandwich laminates with desired flexural stiffness by appropriately choosing the volume fraction. Potential weight reduction for sandwich laminates during the air bending process was presented.

Mechanical Properties of 7075-T6 Aluminum Alloy in Electrically Assisted Forming

The coupling effects of electrical pulse, temperature, strain rate, and strain on the flow behavior and plasticity of 7075-T6 aluminum alloy were investigated and characterized. The isothermal tensile test and electrically assisted isothermal tensile test were performed at the same temperature, and the typical models were further embedded in ABAQUS for numerical simulation to illustrate the electroplastic effect. The results showed that electrical pulses reduced deformation resistance but greatly increased elongation. Compared with the traditional Johnson–Cook model, the proposed modified electroplasticity constitutive equations have a certain improvement in calibration accuracy for a highly nonlinear and thermoelectric coupling dynamic behavior. Moreover, combined with the electrically assisted three-point bending experiment, it was found that the springback angle decreases with the increase in current density. This is very close to the experimental result, further verifying the effectiveness of the thermoelectric coupling constitutive equation.

Ultra-large springback bending strain and its atomistic mechanism in Ni nanowires

Ultra-large springback bending strain and its atomistic mechanism in Ni nanowires

Multi-scale finite element analysis of laser-assisted forming of CF/PEEK composite corner structures

Laser-assisted forming can significantly increase the forming efficiency of thermoplastic composites. However, when forming CF/PEEK curved corner structures using laser-assisted forming, bending spring-back generated by the prepreg tape constrains the shape accuracy of the component. The bending deformation of unidirectional resin matrix composite materials is highly nonlinear. In this study, a multi-scale finite element method is used to obtain the bending properties of CF/PEEK composites for bending spring-back phenomenon of thermoplastic composite samples and predict the spring-back angle of CF/PEEK corner structures fabricated via laser-assisted forming. The average material properties were first calculated using RVE. Following this, a mesoscale model was developed to analyze kink deformation of the composite. Finally, the macroscopic prepreg bending spring-back was calculated. It was determined that the main mechanism of corner forming corresponds to the occurrence of a fiber kinking phenomenon on the interior of the corner. Furthermore, spring-back deformation is caused by residual stresses resulting from insufficient fiber kinking. The accuracy of the simulation results is verified via corner forming experiments. This study contributes to a deeper understanding of the spring-back mechanisms of laser-assisted forming of corner structures and provides a theoretical guidance for precision forming of multilayer thermoplastic composite bent structures.

Microstructure evolution and springback behavior in single-pass roll bending of magnesium alloy plates

Microstructure evolution and springback behavior in single-pass roll bending of magnesium alloy plates

The evaluation of the aging process in 15-5 PH materials in terms of formability and microstructure

In this study, the effects of aging heat treatment of 15-5 PH stainless steel material on the mechanical properties, microstructure, and formability were investigated. Instead of cooling in air, cooling in the oven spontaneously was applied in the oven for the first time. Experimental studies show that aging heat treatment was applied for H900, H1025, and H1150 conditions at temperatures of 482 °C, 552 °C, and 621 °C, respectively, and 60 min for H900 and 240 min for H1025 and H1150. It has been observed that controlled cooling in the oven increases the mechanical values of the material obtained by cooling in the air by 8%–10%. The microstructures of the conditions after heat treatment were also examined, and it was observed that the cooling aging heat treatment in the oven caused precipitation hardening in the microstructure of the material. In addition, when evaluating the formability of the results using V-bending, it was observed that materials which could not withstand bending beyond 75° in Condition A (Con A), the initial state of the material, were smoothly shaped in all conditions and at all angles as a result of the cooling process in the oven. A decrease in spring-back angles has been detected due to the decrease in mechanical properties caused by increasing aging temperature. The highest spring-back value was also observed on a 75° bending die with 10.948° in the H900 condition which has the highest mechanical properties.

Bending properties and deformation micromechanisms of near-α titanium alloy sheets/foils considering initial texture characteristics and size effect

Bending properties and deformation micromechanisms of near-α titanium alloy sheets/foils considering initial texture characteristics and size effect

Springback behavior after air bending of pre-strained AA 6016-T4 sheets: Influence of dislocation density and backstress on model accuracy

Springback behavior after air bending of pre-strained AA 6016-T4 sheets: Influence of dislocation density and backstress on model accuracy

A novel integrated hot forming with in-situ stress relaxation-aging for titanium alloy thin-walled components

A novel integrated hot forming with in-situ stress relaxation-aging for titanium alloy thin-walled components

Cryogenic springback of 2219-W aluminum alloy sheet through V-shaped bending

Cryogenic springback of 2219-W aluminum alloy sheet through V-shaped bending

Effect of ultrasonic vibration on the roll bending deformation behavior of ultra-thin-walled corrugated sheets

Effect of ultrasonic vibration on the roll bending deformation behavior of ultra-thin-walled corrugated sheets

Optimization of springback parameters of an aluminum 1050 alloy by V-bending

Abstract Springback, one of the fundamental properties of parts formed by V bending, is the dimensional deviation caused by elastic recovery. Numerical estimation and compensation of springback is essential because it affects the workpiece’s dimensional accuracy and geometry and will cause serious errors, especially during the assembly process. This study investigated the effects of process parameters such as sheet thickness and die angle on springback behavior on 1,050 aluminum experimentally and numerically. Experiments were planned according to Taguchi’s L9 orthogonal array. Sheet thickness (1 mm, 1.5 mm, and 2.5 mm) and die angle (90, 135 and 150°), were selected as forming parameters. Springback was calculated after the tests. Optimization of the parameters was evaluated using the signal/noise ratio approach. The effectiveness of parameters on results was determined by analysis of variance (ANOVA). It has been observed that the springback angle decreases with increasing sheet thickness, but springback angle decreases with increasing die angles. It has been seen that the experimental and numerical study results confirm each other. The variance analysis determined that the die angle was the most dominant springback parameter (90.9 %). Second is the sheet thickness (5.79 %).

Effect of weld-line position on springback behavior in advanced high-strength steel tailor-welded blanks on hat-shaped bending application

Effect of weld-line position on springback behavior in advanced high-strength steel tailor-welded blanks on hat-shaped bending application

Effects of Thermoforming Parameters on Woven Carbon Fiber Thermoplastic Composites.

The quality of woven carbon fiber fabric/polycarbonate thermoplastic composites after thermoforming and demolding was investigated using finite element simulation and the Taguchi orthogonal array. The simulation utilized a discrete approach with a micro-mechanical model to describe the deformation of woven carbon fabric, combined with a resin model. This simulation was validated with bias extension tests at five temperatures. The thermoforming process parameters considered were blank temperature, mold temperature, and blank holding pressure, with three levels for each factor. Optimal values for the fiber-enclosed angle, spring-back angle, mold shape fitness, and the strain of the U-shaped workpiece were desired. The results indicated that the comparison of the stress-displacement curve of bias extension tests verified the application of the discrete finite element method. Results from the Taguchi array indicated that blank holding pressure was the dominant parameter, with the optimal value being 1.18 kPa. Blank temperature was the second most significant factor, effective in the range of 160 °C to 230 °C, while mold temperature had a minor effect. Furthermore, the four quality values are dependent and have a similar trend. The best combination was identified as a blank holding press of 1.18 kPa, a blank temperature of 230 °C, and a mold temperature of 190 °C.

FORMABILITY CAPABILITIES AND MECHANICAL PROPERTIES OF TITANIUM TAILOR-WELDED BLANKS

Titanium alloys have many applications in aerospace, nuclear and automotive industries and in most parts are in sheet form and require joints of high integrity to meet the design requirements and achieve reliable welds. For weight and cost reduction, the technology of tailor-welded blanks (TWBs) is a promising technology in various components. TWBs are usually semi-finished metallic sheets made of different strengths, materials, and/or thicknesses and a forming process is often needed to manufacture the final components. In this paper, Grade-2 and Grade-5 titanium alloy sheets (Ti-TWBs) were laser welded and subjected to a forming process in U-profile geometry at elevated temperatures. The deformation behaviors of the weld joints after forming process were analyzed by mechanical tests such as tensile and hardness tests. The formability of the welded blanks is assessed based on variations in the geometric changes related to the springback angles. The results showed that there was significant increase in tensile strength with forming temperature increase and the failure mode was changed at 850 °C. The formability of the Ti-TWBs was found to be strongly dependent on the applied process temperatures and forming at 850 °C leads to the lowest springback angle.

The analytical model of crimping springback for large-diameter longitudinal welded pipe

The crimping technique is widely used in the manufacturing process of large-diameter longitudinal welded pipe. In the bending process, the springback is the critical problem affecting the shape, which is the key index of forming quality. So, crimping faces more challenges in accurate springback prediction for difficult-to-form metals such as pipeline steels and non-circular nature of the punch. This paper has established an analytical model of crimping springback for the longitudinal welded pipe. Firstly, the crimping process mathematical model which considered the impact of elastic modulus attenuation on springback calculation during plastic deformation is established, and the cross-section bending moment is calculated based on Hill’s bending theory. Secondly, a semi-analytical and semi-numerical method for calculating the crimping shape is presented. Finally, the comparison of the crimping shape of the real product shows that the calculation accuracy and efficiency of this method can meet the requirements of engineering applications. The relative error of the springback angle calculated by the analytical model is −5.84%, and the absolute error is 0.3°. This method can accurately predict the springback of longitudinal welded pipe after crimping and provide a reference for crimping process optimization.

Experimental investigation on process parameters of laser-assisted robotic roller bending of a thin-walled structure

Laser-assisted robotic roller forming (LRRF) combines the process capabilities of robot-based manufacturing and laser-assisted forming. In this work, the LRRF process was applied to bending DP1180 steel sheets to thin-walled structures designed for seat trails. Comprehensive experimental investigations were conducted to explore the influences of laser power, forming passes and scanning speed on the forming forces, springback and bending radii of final parts. Experimental results show that the effects of process parameters on the springback and bending radii are similar to those on the forming forces, while forming passes make an insignificant difference to the springback. The optimized process window was subsequently determined out of the balance between geometrical accuracy and experimental efficiency. By applying the optimized process parameters (laser power of 750 W, 6 forming passes, scanning speed of 5 mm/s), the peak force during LRRF was reduced to ∼2.1kN. Meanwhile, a thin-walled profile with higher precision was achieved. Specifically, the springback angle was reduced to ∼4.1° and a compact profile with a radius-to-thickness ratio of ∼1.0 was obtained.

Analysis of Springback Characteristics of Bending Unloading for Stainless Steel tubes

Stainless steel tubes are widely used in piping systems in aviation, aerospace and other high-tech fields because of their high strength, excellent corrosion and high-pressure resistance, and good resistance to high-temperature oxidation. This paper takes 304 stainless steel pipe as the research object, based on ABAQUS finite element platform, the springback behaviour of stainless steel pipe in the process of precise bending and forming has been studied in depth. The results show that: pipe bending unloading bending springback angle increases with the increase of the bending angle. The results of the study have important theoretical and practical significance for improving the accurate forming and springback of stainless steel tube bending.

Microstructural evolution and formability of Ti−6Al−4V alloy sheet during electropulsing-assisted bending

Microstructural evolution and formability of Ti−6Al−4V alloy sheet during electropulsing-assisted bending

Forming Characteristics of Tailor Rolled Blank of Aluminum Alloy during Three-Point Bending.

This paper presents an investigation on the forming characteristics of the tailor rolled blank of an aluminum alloy (Al-TRB) during three-point bending at room temperature through experiments and finite element simulations. The strain distribution, spring-back characteristics, and metal flow law of 6000 series Al-TRB during three-point bending are explored. The prepared Al-TRB has good bending properties, and no surface cracks appear in the bending region of the Al-TRB when bent to 180°. Surface roughening occurs on the outside of the bending region. Since the strain in the thick zone is greater than that in the thin zone, the surface roughening in the thick zone is more obvious than that in the thin zone. The spring-back angle in the thin zone is higher than that in the thick zone after three-point bending, and the overall spring-back angle of Al-TRB becomes larger with an increasing bending angle. When the transition zone of Al-TRB is centered and the length of the transition zone is certain, as the length of the equal-thickness zone increases, the spring-back angle of the thin zone is larger, while the spring-back angle of the thick zone is smaller. Under the premise of a certain total length of Al-TRB and the length of the transition zone, the larger the length proportion of the thin zone, the larger the overall spring-back angle of Al-TRB, and the larger the length proportion of the thick zone, the smaller the overall spring-back angle of Al-TRB. In addition, a slight metal flow phenomenon exists during three-point bending, which shows that the metal in the bending region will flow to the thick zone, and the metal at the edge will flow to the thin zone. At the same time, there are localized thickening and thinning phenomena in Al-TRB. This study is helpful because it provides theoretical guidance for designing molds for the actual production of Al-TRB parts for automotives.