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To overcome the limitation in formability at room temperature, manufacturers have developed magnesium alloys with remarkable properties by adding rare-earth elements. The rare-earth magnesium alloys behave differently from the conventional alloys, especially with respect to their coupled anisotropic and strain rate sensitive behavior. In the current work, such behavior of the rare-earth Mg alloy ZEK100 sheet at room temperature is investigated with the aid of the elastic viscoplastic self-consistent polycrystal plasticity model. Different strain rate sensitivities (SRSs) for various deformation modes are employed by the model to simulate the strain rate sensitive behaviors under different loading directions and loading rates. Good agreement between the experiments and simulations reveals the importance and necessity of using different SRSs for each deformation mode in hexagonal close-packed metals. Furthermore, the relative activities of each deformation mode and the texture evolution during different loadings are discussed. The anisotropic and strain rate sensitive behavior is ascribed to the various operating deformation modes with different SRSs during loading along different directions.

Sheet metal channels with variable sections or local features have been widely used in automobile and construction industries, and novel forming techniques, such as flexible roll forming process, flexibly-reconfigurable roll forming process, Deakin’s flexible forming facility and chain-die forming recently have been developed to manufacture those channels. In this paper, the feasibility of chain-die forming technique to manufacture channels with variable sections are systematically investigated through experiment and finite element simulation by taking 6 types of channel products as demonstration, including three variable-width and three variable-depth profiles. The forming process of the channels shows a combination of roll forming and stamping, and this roll-stamp mode is greatly potential in manufacturing a wide variety of channels with variable cross-sections. The formability for roll-stamp forming variable-depth channels is evaluated through finite element simulation and forming limit diagram. The roll-stamp mode can be discomposed into roll forming longitudinally and stamping vertically, and can achieve a reduction in forming load by the maximum of 33.9% compared with the conventional stamping in forming the flange step product. The forming direction sensitivity of the variable-width feature is discussed from the aspect of web arch height development.

The deformation behavior of the mush zone for superalloy during investment casting directly affects the dimensional control of casting has puzzled many engineers and scientists for years. Numerical simulations are not directly useful to predict the most suitable pattern allowances. A new data-driven approach to be effectively used for pattern allowance and casting process parameters prediction is proposed. The constitutive relationships and deformation parameter from high-temperature mechanical tests on superalloy K4169 is reported. The inputs are alloy temperature, shell temperature, and pattern allowance with the outputs of diameter and ovality of the ring-to-ring casting, respectively. It turns out that the shell temperature is the most momentous factor that governs the dimensional variability in ovality. An RBF-based approximation model is established and the optimized parameters are the alloy temperature 1500.5°C, shell temperature1052.5°C, and the pattern allowance 1.7258%. The optimized results agree well with the observed in practical casting and the ring-to-ring casting tolerance has been optimized as required within CT6 grade. The proposed method is believed to benefit to provide theoretical guidance for casting practice. The data-driven approach used in this research can be easily applied to different materials and different kinds of casting that are subject to dimensional control upon solidification.

Chain-die forming can be used to manufacture Advanced High Strength Steels (AHSS) channel components. Flange wrinkling is one of typical defects for chain-die formed products. The purpose of this paper is to investigate the cause of flange wrinkling in chain-die forming of AHSS and to propose a potential method to suppress it. A hat channel product with a curved axis is formed as a benchmark to illustrate the mechanism of flange wrinkling in chain-die forming. When forming such a profile, longitudinal compressive strain of the sheet metal is geometrically necessary, and the compression has to be achieved by plastic wrinkling due to the insufficient restricted boundary condition. Finite element models are established to better understand the complex interaction between the tools and plate. An initial imperfection calculated from the differential equilibrium equations for elastic plates with small deflections is implemented into the finite element model to predict occurrence of the flange wrinkling. In order to eliminate the wrinkling defect, an M-shaped die design is proposed, which intends to provide additional restriction to the sheet metal and increase longitudinal and transversal tension. A three-factor, three-level Design of Experiment (DOE) scheme for the M-shaped die design is conducted. The DOE results show that a benign wrinkling always corresponds to a larger compressive strain and the width of the ears for M-shaped dies is a decisive factor to suppress wrinkling. The verification experiments show that the plastic flange wrinkling is completely eliminated by employing the proposed method.

To assist designers in making comprehensive decisions for objective design values (DVs) and subjective preference values (PVs) during the design solution evaluation stage, this study builds an information-intensive design solution evaluator (IIDSE) that combines multi-information from DVs and PVs. In the IIDSE, the importance degrees of the DVs and PVs are analysed based on their differences. Then, according to the importance classifications , values, characteristics, and numbers of DVs and PVs, a multi-information fusion (MIF)-based ideal solution definition strategy, which covers quantitative criteria with i) benefit characteristics, ii) cost characteristics, and iii) qualitative criteria, is proposed. A rough multi-criteria decision-making (R-MCDM) model is used to evaluate an alternative by computing its deviation from the defined ideal solution. The effectiveness of the IIDSE was validated via empirical comparisons. Experiment I showed that the MIF-based strategy is compatible with different R-MCDM models for selecting the preferred and best performing solution. In experiment II, among the R-MCDM models, R-COPRAS plus the MIF-based strategy is the best combination for constructing the IIDSE. Experiments III and IV demonstrated that the IIDSE can obtain more reasonable solutions compared with classical evaluators, especially in the case where conflictions between the objective DVs and subjective PVs exist.

Chain-die forming is an emerging sheet metal technique for manufacturing advanced high strength steel (AHSS) products. Springback and longitudinal bow are two of the major shape defects in gradual forming. In this study, the springback and longitudinal bow of AHSS in chain-die forming of hat and U profiles are investigated through experiment and finite element simulation. The disparity of springback along the longitudinal direction and disparate longitudinal bow signifies complex deformation processes of chain-die forming. Finite element simulation of the chain-die forming process gives an insight into the formation of non-uniform springback and longitudinal bow. The gradual forming process by one die block after another causes bending and reverse-bending deformation in the web area and the redundant deformation of the sheet metal, which further leads to non-uniform bending moment and accumulated stresses along the longitudinal direction. At the same time, the redundant deformation will also result in the longitudinal strain on the edge, while the downhill deformation decreases the maximum longitudinal strain at the edge and introduces the longitudinal strain on the web. The different non-uniform longitudinal strain distribution along the transversal direction causes disparate longitudinal bow behaviors for chain-die formed AHSS hat and U profiles, downward bowing and upward bowing respectively. By the established model, the disparate springback and longitudinal bow behavior can be determined, which also contribute to the process design for chain-die formed AHSS products.

The ingredient devices tend to be designed and fabricated with microscale, high accuracy, and complex geometry and are subjected to complex loading. Many experiments have proved that the size effect plays a significant role in designing and manufacturing an engineering component. This size effect is largely attributed to the grain size and the strain gradient. While the grain size effect was omitted in conventional strain gradient theories, an extended model that considers both effects of grain size and strain gradient has been proposed in the current work (denoted as GMSG). The proposed GMSG model has been implemented into the finite element method (denoted as GMSG-FEM) to investigate the size effect of copper wires under complex working conditions. The simulation results show that the hollow structure can improve the bearing capacity of the micro-wires under torsion. Among micro-wires with different cross-sections, the bearing capacity of the micro-wire with a circular section is the largest, followed by those with square and triangle sections. Complex loading also has an important influence on stress distribution. Based on the current study, it can be envisaged that the GMSG-FEM could be a useful tool in engineering applications where the size effect has to be considered.

Due to their low symmetry in crystal structure, low elastic modulus (∼45 GPa) and low yielding stress, magnesium (Mg) alloys exhibit strong inelastic behaviors during unloading. As more and more Mg alloys are developed, their unloading behaviors were less investigated, especially for rare-earth (RE) Mg alloys. In the current work, the unloading behaviors of the RE Mg alloy ZE10 sheet is carefully studied by both mechanical tests and crystal plasticity modeling. In terms of the stress–strain curves, the inelastic strain, the chord modulus, and the active deformation mechanisms, the substantial anisotropy and the loading path dependency of the unloading behaviors of ZE10 sheets are characterized. The inelastic strains are generally larger under compressive Loading–UnLoading (L–UL) than under tensile L–UL, along the transverse direction (TD) than along the rolling direction (RD) under tensile L–UL, and along RD than along TD under compressive L–UL. The basal slip, twinning and de-twinning are found to be responsible for the unloading behaviors of ZE10 sheets.

Spot welds are extensively used on autobodies and also a key factor affecting the performance of automobiles. Automatic detection of spot welding based on machine vision provides an effective way for car body welding quality control. Considering the traditional image processing methods are greatly disturbed by the environment and have unsatisfying robustness, a network model for small object detection is proposed to detect the position and quality of the spot welding of the car body. Based on the existing You Only Look Once (YOLOv3) model, the proposed model has three novel improvements. Firstly, the lightweight network MobileNetV3 is introduced to replace the backbone network of YOLOv3 to ensure accuracy and real-time performance. Secondly, to improve the model’s ability for small object detection, a new feature pyramid network (FPN) with efficient cross-scale connections is proposed, which allows easy and fast multiscale feature fusion. Finally, considering the shortcomings of intersection and union ratio (IoU) loss, complete IoU (CIoU) loss is used to improve convergence speed and regression accuracy. Moreover, novel data augmentation is used to enrich the dataset during the model training. Quantitative results on the spot welding dataset show that the proposed approach achieves successful results for resistance spot welding vision inspection.

Summary Enhancing automobile fuel efficiency is crucial to decarbonizing the transport sector. Recent studies have revealed a gap between real-world fuel efficiency and results from laboratory tests, where “off-cycle” auxiliary devices, like air conditioning (AC) systems, are not turned on. AC consumes the most energy among all off-cycle devices; however, the exact contribution of AC to fuel consumption remains unclear. Here, by analyzing 1 million trip-level fuel efficiency records from China, we show that AC use when the temperature exceeds 25°C increases gasoline consumption annually by 1.3%. The amount differs across car models, with those produced by Chinese manufacturers showing relatively lower AC efficiency. Improving AC efficiency could cost-effectively reduce CO2 emissions by 1.6–2.4 million tons in China every year. Therefore, we suggest integrating off-cycle devices into future fuel efficiency regulations, which will reveal the fuel efficiency gap, incentivize car manufacturers to develop high-efficiency devices, and further tap this emissions reduction potential.

The aim of present work is to develop a crystal plasticity modeling approach to integrate slip, dynamic recrystallization (DRX) and grain boundary sliding (GBS) for simulating the deformation behavior and texture evolution of magnesium alloys at high temperatures. Firstly, the deformation mechanisms of an AZ31B Mg alloy sheet at 300 °C were investigated by examining texture and microstructure evolution during uniaxial tension and compression tests. DRX refines microstructure at strains less than 0.2, and subsequently GBS plays a significant role during deformation process. A GBS model is developed to evaluate strain and grain rotation induced by GBS, and implemented into the polycrystal plasticity framework VPSC. The VPSC-DRX-GBS model can well reproduce the stress−strain curves, grain size, texture evolution and significant texture differences in tension and compression tests due to GBS. The calculated GBS contribution ratio in tension is obviously higher than that in compression due to easier cavity nucleation at grain boundaries under tension loading.

The geometrical shape of the gating system and the casting process are vital to the occurrence of shrinkage porosity, and the effects of their combination directly determine the desired high-quality casting. Casting simulation plays a significant role in the deduction of the trial and error method for gating system design in investment casting, which is time-consuming. A breakthrough in optimization design often requires a comprehensive understanding of the geometrical structure of the gating system and the complex process parameter to generate a novel data-driven framework that improves the higher quality of casting and reduces the period of design. This paper proposed a data-driven framework to investigate the optimal gating system design integrated with complex casting processes through RBF optimization algorithm with the target of porosity-free casting as well as high casting yield percentage. The results demonstrate that the optimization of the gating design is more inspiring with high accuracy and high efficiency, and the casting yield is increased by 14.91%. Furthermore, the verification between simulation and experiments shows good agreement. The demonstrated data-driven approach is feasible and effective and can be extended not only incorporating the geometrical structure of the gating system and casting processes in investment casting optimization but also other potential types of casting design.

A phase field model was presented to investigate the effect of particles-pinning on grain boundary migration in materials containing stored energy differences across the grain boundaries. The accuracy of the phase field framework was examined by comparing the simulated results with theoretical predictions. The pinning effects of coherent and non-coherent second phase particles on the boundary migration were studied in triple-grain models. 2D simulations with second phase particles of different sizes or different area fractions were performed. The effect of stored energy difference across the boundary on the particles-pinning was also investigated. The results showed that the pinning effect could be enhanced by the decrement of the particle size and the increment of particle area fraction. Increasing the stored energy difference across the grain boundary induced higher grain boundary migration velocity and weaker particles-pinning.

The manipulation of liquid droplets on a specific surface with reversible wettability is of great importance for various applications from science to industry. Herein, the concept of a smart, flexible photodriven droplet motion (PDM) device with programmable wettability is designed using the 2D material of MXene film. Because of the MXene photothermal property, the Vaseline layer in the device is in transition between solid and liquid states under the heat transformation due to light illumination, thus attractively producing a reversible wettability for liquid motion with respect to sliding and pinning. Multifarious pathways for liquid motion could be designed through the flexibility of light illumination, which is a revolutionary enhancement in diverse liquid motion to form the desired pathways. In addition, we demonstrated liquid motion under illumination of the back face, which has a profound influence on applications, such as microfluidic systems, microengines, and liquid manipulation.

Gas embolism is a potentially serious complication of hysteroscopic surgery. It is particularly necessary to monitor bubble parameters in hysteroscopic images by computer vision method for helping develop automatic bubble removal devices. In this work, a framework combining a deep edge-aware network and marker-controlled watershed algorithm is presented to extract bubble parameters from hysteroscopy images. The proposed edge-aware network consists of an encoder-decoder architecture for bubble segmentation and a contour branch which is supervised by edge losses. The post-processing method based on marker-controlled watershed algorithm is used to further separate bubble instances and calculate size distribution. Extensive experiments substantiate that the proposed model achieves better performance than some typical segmentation methods. Accuracy, sensitivity, precision, Dice score, and mean intersection over union (mean IoU) obtained for the proposed edge-aware network are observed as 0.859 ± 0.017, 0.868 ± 0.019, 0.955 ± 0.005, 0.862 ± 0.005, and 0.758 ± 0.007, respectively. This work provides a valuable reference for automatic bubble removal devices in hysteroscopic surgery.

The influence of the solidification process parameters on the microstructure is still identified by the trial and error method. It is common practice to perform multiple casting tests to defecate the optimum process parameters for high-quality casting parts. In order to establish the solidification-microstructure relationship, a high-efficiency experimental method is proposed to accelerate the speed of finding the optimum casting process parameters by the controlled cooling rate of 0.25 °C/s, 1 °C/s, 5 °C/s, and 10 °C/s, respectively. It demonstrated that the physics simulation can successfully predict the microstructure of the GTD-222 Ni-based superalloy casting and the relationship between the secondary dendrite arm spacing (SDAS) and cooling rate is λ2 = 76.4747(GV)−0.2926.The response behavior of secondary dendrite arm spacing is sensitive to the change of solidification parameters. Moreover, the microhardness tends to decrease along the axial direction as well. The relationships between the temperature gradient, cooling rate, and microstructure are discussed as well. The results also show that the prior model of the numerical simulation and the physical simulation of the high-efficiency experiment design can reproduce the conventional casting conditions and the high-efficiency experiment can be applied to other casting studies of all kinds for the enhancement of time- and cost-saving.

Magnesium alloys usually lack “operative deformation slip mechanisms” because of their hexagonal close-packed structure. Therefore, the mechanical behavior of magnesium alloys at different temperatures is dictated by other deformation mechanisms such as twinning, detwinning, secondary twinning, or dynamic recrystallization (DRX). Twinning and DRX can affect the development of grain size and orientation distribution, as well as the deformation behavior of magnesium alloys. The current understanding of the mechanisms and mechanics of these different deformation modes and their implementation in crystal plasticity-based modeling are highlighted in this article. Future directions in the development of constitutive models are also discussed.

Abnormally large grains (ALGs) appear after annealing of prestrained multiport extrusion (MPE) tubes, which will significantly degrade the mechanical properties of the tubes. In the present work, the underpinning mechanisms of ALGs’ formation are probed through experiments. MPE tubes made of A3102 alloy are prestrained by roll leveling with different thickness reduction ratios and are then subjected to annealing at 600 °C for different times. Microstructural evolutions during annealing are characterized through electron backscatter diffraction (EBSD), in terms of crystallographic orientation, grain size distribution, grain boundary characters, and residual plastic strain. Uniaxial tension tests are carried out on the annealed tubes to study the effect of annealing on tubes’ strength. The thickness reduction prior to annealing produces heterogeneous deformation in tubes. The hard zones formed near grain boundaries and triple junction (TJs) are responsible for recrystallized nucleation in annealing. The duration of the identified incubation period for grain growth is inversely proportional to the thickness reduction ratio. The strain-free nuclei formed in the incubation period can grow fast into ALGs by means of strain-induced boundary migration. Further grain growth is inhibited by grains’ impingement after the strained grains are exhausted. Grains consumed by the growing ALGs tend to establish special boundary relationships with the ALGs and can turn into island grains. The significant reduction of tubes’ strength after annealing is attributed to the diminishment of grain boundaries caused by the formation of ALGs.

The dependencies of solidification parameters of complex castings on microstructure at a microscopic scale were investigated by numerical simulation combined with physical simulation. A nov...

In this paper, a smooth and time-optimal S-curve trajectory planning method is proposed to meet the requirements of high-speed and ultra-precision operation for robotic manipulators in modern industrial applications. This method utilizes a piecewise sigmoid function to establish a jerk profile with suitably chosen phase durations such that the generated trajectories are infinitely continuously differentiable under the given constraints on velocity, acceleration and jerk. All the trajectory parameters are derived with an analytical algorithm to ensure an acceptable computational cost. This S-curve model achieves a greater efficiency than the trigonometric models, while avoiding the high complexity presented by conventional high order polynomial models. The trade-off between efficiency and smoothness can be modulated by the limit value of the snap (the derivative of jerk), this feature is advantageous for adapting to different task requirements. Furthermore, a synchronization strategy is suggested to coordinate multi-axis motions, enabling the full capabilities of the actuators to be exploited. The feasibility and practicality of the proposed approach is evaluated by the simulation and experimental studies in comparison with other benchmark techniques in the literature.

The manufacturing process of multiport extrusion tubes generally includes homogenization, extrusion, roll leveling and heat treatment. In order to investigate the influence of the manufacturing procedures on strength variation of multiport extrusion tubes made of A1100 and A3102 alloys, the tube fabrication experiments and following materials characterization are carried out. The alloys’ stress–strain curves after every processing procedure are measured, and pressure-bearing capacity of the tubes is tested. The tubes’ strength and pressure-bearing capacity reach the peak values after straightening process and drop to the minimum after annealing. The contributions of solid solution hardening, grain boundary hardening and constituent particle strengthening to yield strength are evaluated. It is deduced that cluster hardening is the dominant strengthening mechanism for the as-homogenized and as-extruded samples; the contribution of clusters is second to work hardening after straightening process; slight cold work in conjunction with high-temperature annealing accelerates abnormal grain growth. The loss of strength increment from clusters can be interpreted by the remarkable reduction of high-angle grain boundaries after abnormal grain growth.

Hot forming often has to be resorted when processing metals with limited room-temperature formability, such as aluminum, magnesium, etc. The temperature rise induced by plastic work, especially under high strain rates, can exert significant effect on mechanical response as well as dynamic recrystallization of deformed metals. In the present work, a polycrystal plasticity based thermo-mechanical-dynamic recrystallization (DRX) coupled approach is established by implementing thermo-mechanical effect in a VPSC-DRX model where a grain nucleation and growth model is implemented into the VPSC framework. The modeling parameters associated with various slip modes, temperatures and strain rates are calibrated by isothermal compression experiments, and then evolution functions of hardening and DRX related parameters with respect to temperature and strain rate are established. The integrated computation of plastic deformation, texture, grain size and temperature update in hot deformation of metals can be achieved. The proposed method is verified and then applied to simulate hot extrusion processes of magnesium alloy bars at three different ram speeds. The influences of ram speed on development of deformation texture and grain size are analyzed. The temperature rise due to plastic work enhances stress softening and stimulates grain growth, makes the macro/micro responses of materials no longer monotonically varied with strain rate.

The cage roll forming process improves the flexibility of electrical resistance welding (ERW) pipes manufacturing by employing several groups of cage rolls, but poses great challenge to flower design and roll positioning, since the flower pattern and rolls’ positions are no longer one-to-one correlated as in conventional roll forming processes. In the present work, a forming flower design method for cage roll forming of ERW pipes is proposed, considering the transversal bending characteristics of the sheet metal, especially the existence of “non-bending area”. Furthermore, based on kinematic analysis of the cage roll frame, a roll positioning method is put forward by implementing flower pattern and enforcing the geometric constraint condition between rolls and the steel strip. The proposed flower pattern design and roll positioning methods are demonstrated by the cage roll forming of two ERW pipes. The forming processes by using the newly designed parameters and old experience based parameters are compared. The proposed method provides a science based process design method for cage roll forming processes. To the best of our knowledge, the present work is the first effort on developing flower pattern and roll positioning design methods for the cage roll forming process of ERW pipes.

It is common practice for Singapore wastewater treatment plant (WWTP) to treat primary sludge and secondary active sludge by anaerobic digestion (AD) to recover energy through biogas. However, sewage sludge (SS) is low in biodegradable organic matter and biomethane potential, which result in low AD efficiency both from a processing and an economic standpoint. Co-digestion of SS together with food waste (FW) not only provides a practical alternative for FW management, but also improves the performance and energy efficiency of often under-performed anaerobic digester in WWTP, as the potential synergistic effect between FW and SS could increase the biogas production and system stability. Prior to applying co-digestion in reality, life cycle assessment (LCA) is required to understand the environmental advantages and drawbacks of the co-digestion strategy so that it can be implemented more sustainability. It was found that everyday 4400 tonne of SS and 1000 t of FW were generated in Singapore. For co-digestion, the possible outcomes may be categorized as neutral, synergistic, and antagonistic, if methane production from the mixture is equivalent, higher or lower than the sum of mono-digestion. The LCA results show that when the antagonistic situation happens, the co-digestion system becomes much less favorable, although it requires less water consumption and land foot print. Therefore, the key efforts of plant manager are suggested to be spent on the maximization of biogas output.

The increasing challenge in waste disposal and high dependency on imported fossil fuel has compelled Singapore to make continuous efforts in advancing waste to energy (WTE) technology, which could ensure sustainable development on one hand and energy resilience on the other hand. This paper summarizes the current WTE practices and research trends in Singapore, covering anaerobic digestion (AD), gasification, combustion-based biomass combined heat and power (CHP) production, and incineration, with the aim to define future perspectives of Singapore WTE application. Among the different aspects assessed, source-separated food waste (FW) and brown water present the biggest energy potential if AD is adopted instead of incineration. Given that the purity of source separated waste determines the extent of recovered energy, suggestions are made to increase the participating rate in source separation among Singapore residents, such as environmental education through social media and phone apps and proper facilities installation at household and community. Moreover, additional benefits can be credited to WTE system if the waste to material practice is also conducted on top of energy production.

The low lattice symmetry and limit deformation modes of wrought magnesium (Mg) alloys restrain it from wide use in aerospace and automobile industries. Addition of rare earth (RE) elements has been used as the texture modifier to improve the formability of Mg alloys. Mg-1Al and Mg-4Y extruded alloys were investigated to probe the effects of the Y addition on the texture and microstructure of Mg alloys. It is demonstrated that the non-RE alloys exhibit a \( \left\{ {10\bar{1}0} \right\} \) or \( \left\{ {10\bar{1}0} \right\} - \left\{ {11\bar{2}0} \right\} \) texture depending on the recrystallized fraction, whereas the yttrium (Y) Mg alloys develop a \( \left\{ {11\bar{2}1} \right\} \) “RE texture” component. The mechanism of “RE texture” component’s formation was studied by using the electronic backscattered diffraction (EBSD) technique. The results indicate that the formation of both \( \left\{ {11\bar{2}0} \right\} \) and \( \left\{ {11\bar{2}1} \right\} \) texture components is closely related to the continuous dynamic recrystallization (CDRX) of the grains which nucleate in the mantle regions of the original grains.

Post-extrusion cold deformation followed by brazing has a significant effect on mechanical properties of micro-channel tubes used in heat exchangers. To understand this relationship, cold rolling with different thickness reductions (0–15%) and a following brazing are conducted on extruded tubes, and the microstructure and strength are examined. The results show that with increasing rolling reduction, tensile strength and burst strength of the as-rolled tubes increase monotonously. While after brazing, both strengths decline obviously, and them decrease first and then increase with increasing rolling reduction. The change is attributed to recrystallization and grain growth observed in the post-braze tubes. Driven by different levels of strain from the rolling, recrystallized grain size increases first and then decreases. At 5% thickness reduction, abnormal large grains form in the web and result in the minimum post-braze strength. Finally, the ductile fraction mode is observed in the web, which shear strength determines the burst strength.

The hot deformation behaviors of the SJTU-1 alloy, the high-throughput scanned casting Nickel-based superalloy, was investigated by compression test in the temperature range of 900 to 1200 °C and strain rate range of 0.1–0.001 s−1. The hot processing map has been constructed with the instability zone. At the beginning of hot deformation, the flow stress moves rapidly to the peak value with the increased strain rates. Meanwhile, the peak stress is decreased with the increased temperature at the same strain rates. However, the peak stress shows the same tendency with the strain rates at the same temperature. The optimum hot deformation condition was determined in the temperature range of 1000–1075 °C, and the strain rate range of 0.005–0.1 s−1. The microstructure investigation indicates the strain rate significantly affects the characteristics of the microstructure. The deformation constitutive equation has also been discussed as well.

The mechanical properties and damage behaviors of carbon/epoxy woven fabric composite under in-plane tension and compression are studied at the meso-scale level through experiment and simulation. An efficient representative volume element (RVE) modeling method with consistent mesh, high yarn volume fraction and realistic geometry is proposed. The material constitutive laws with plasticity, tension-compression asymmetry and damage evolution are established for the three components - yarn, matrix and interface, respectively. Significantly different mechanical properties and damage evolutions are observed depending on loading conditions and initial geometry characteristics. It shows a non-linear stress-strain curve with clear transition region and intensive damage in tension, while a quasi-linear behavior up to facture is observed in compression with little damage prior to final fracture. Moreover, compared to the constant Poisson's ratio with straining in compression, a dramatic increase in Poisson's ratio appears in tension. Simulation shows damage mechanisms including transverse damage, matrix damage and delamination, which all play critical roles in the property evolution. In particular, the rapid damage accumulation after elastic deformation destroys the strong bonds and causes the easy deformation of transverse yarns which results in the transition region and large Poisson's ratio in tension. All the mechanical behaviors and damage evolutions are well captured and explained with the current RVE model.