Ultra-large aluminum shape casting:Opportunities and challenges

Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and manufacturing.This paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and benefits.Factors affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and performance.Metallurgical analysis and mechanical property assessment of an ultra-large aluminum shape casting are presented.Challenges are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.

Developments and perspectives on the precision forming processes for ultra-large size integrated components

In order to meet the requirements of high reliability,long-lifetime and lightweight in a new generation of aerospace,aviation,high-speed train,and energy power equipment,integrated components are urgently needed to replace traditional multi-piece,welded components.The applications of integrated components involve in a series of large-size,complex-shaped,highperformance components made of difficult-to-deform materials,which present a huge challenge for forming ultra-large size integrated components.In this paper,the developments and perspectives of several extreme forming technologies are reviewed,including the sheet hydroforming of ultra-large curved components,dieless hydroforming of ellipsoidal shells,radial-axial ring rolling of rings,in situ manufacturing process of flanges,and local isothermal forging of titanium alloy components.The principle and processes for controlling deformation are briefly illustrated.The forming of typical ultra-large size integrated components and industrial applications are introduced,such as the high strength aluminum alloy,3m in diameter,integrated tank dome first formed by using a sheet blank with a thickness the same as the final component,and a 16m diameter,integrated steel ring rolled by using a single billet.The trends for extreme forming of ultra-large size integrated components are discussed with a goal of providing ideas and fundamental guidance for the further development of new forming processes for extreme-size integrated components in the future.

Manufacturing of ultra-large plate forgings by unfolding and flattening of thick cylinders

Ultra-large plate forgings are foundation of heavy machinery,but many parts of the type cannot be made by conventional technologies due to the characters of extreme manufacturing in terms of size and quality requirements.This paper introduced a systematically method called cylinder unfolding method(CUM)for producing large plate forgings,by using a serial of operations including“splitting”,“unfolding”,and“flattening”of a thick cylinder obtained from saddle forging.The technological route of CUM was presented in detail with an example of plate forging with the horizontal sizes of 6100 mm and thickness of 300 mm.The deformation features of saddle forging for fabricating transitional cylinders were analyzed,and then the subsequent handling steps including splitting,unfolding and flattening of the cylinder,as well as the auxiliary processing,were addressed.The practice proved that CUM can provide an efficient way for manufacturing ultra-large plate forgings and meet the strict requirements in geometry and mechanical performance,without highly increasing the investments of forming equipment and tooling.

On a plastic instability criterion for ultra-large radial-axial ring rolling process with four guide rolls

A dynamic mechanical model is proposed to describe the complexing actions of all the rolls on the ring during the ultra-large radial-axial ring rolling(RARR)process with four guide rolls.Based on the model,the calculation models for bending moment and normal stress at any section of the ring are deduced by force method.If the maximum section bending normal stress exceeds the yield stress of the ring materials,the ring will be distorted thus leading to the instability of the RARR process.According to this,a plastic instability criterion for the ultra-large RARR process with four guide rolls is developed,based on which a mathematical model to calculate the critical guide force for avoiding plastic instability of ring is obtained.The influence rule of the position of guide roll on the dangerous ring section of plastic instability is revealed,from which it is found the dangerous ring section mainly appears at the radial and axial deformation regions and the contact positions of the guide rolls and ring.The optimized layout of guide roll around the ring in favor of stability is determined to be about a1=61°and a2=119°.The plastic instability criterion is proven to be reliable from the aspects of the critical guide force,the section bending moment and normal stress and the dangerous ring section of plastic instability.Intelligent simulation case studies for the RARR process of ultra-large aluminum alloy ring indicate that the stable forming of the process can be effectively realized by regulating the guide force based on the plastic instability criterion.This work could provide a valuable guidance for the control of guide rolls and the optimization of the ultra-large RARR process with four guide rolls.

A 2D covalent organic framework with ultra-large interlayer distance as high-rate anode material for lithium-ion batteries

Covalent organic frameworks(COFs)have been broadly investigated for energy storage systems.However,many COF-based anode materials suffer from low utilization of redox-active sites and sluggish ions/electrons transport caused by their densely stacked layers.Thus,it is still a great challenge to obtain COF-based anode materials with fast ions/electrons transport and thus superior rate performance.Herein,a redox-active piperazine-terephthalaldehyde(PA-TA)COF with ultra-large interlayer distance is designed and synthesized for high-rate anode material,which contains piperazine units adopting a chair-shaped conformation with the nonplanar linkages of a tetrahedral configuration.This unique structure renders PA-TA COF an ultra-large interlayer distance of 6.2Å,and further enables it to achieve outstanding rate and cycling performance.With a high specific capacity of 543 mAh·g^(−1) even after 400 cycles at 1.0 A·g^(−1),it still could afford a specific capacity of 207 mAh·g^(−1) even at a high current density of 5.0 A·g^(−1).Our study indicates that expanding the interlayer distance of COFs by rational molecular design would be of great importance to develop high-rate electrode materials for lithium-ion batteries.

Wearable and washable textile-based strain sensors via a single-step, environment-friendly method

Recently, soft and stretchable strain sensors that can be incorporated into textiles have attracted significantly increasing interest for use in a diverse range of applications. However, the simple fabrication of stretchable devices that exhibit excellent sensing performance, are highly durability and are a good fit to the human body remains a challenge. Herein, we describe the fabrication of a new flexible strain sensor on a traditional polyester fabric using a one-step method that involves the reduction of graphene oxide(GO) using ascorbic acid(L-AA). The resulting textile-based strain sensors could be washed, exhibited long-term stability,and had a negative linear response that gave a good sensing response when used in wearable applications. In addition to effectively detecting human motions, the textile was modified such that it could detect ultra-large deformations. The impressive mechanical performance, durability and the ability to capture and monitor a variety of human actions and motions mean that these textile-based sensors have great potential in biomonitoring, soft co-robotics, and human-machine interactions.

Exploration on learning molecular docking with deep learning models

Background:Molecular docking-based virtual screening(VS)aims to choose ligands with potential pharmacological activities from millions or even billions of molecules.This process could significantly cut down the number of compounds that need to be experimentally tested.However,during the docking calculation,many molecules have low affinity for a particular protein target,which waste a lot of computational resources.Methods:We implemented a fast and practical molecular screening approach called DL-DockVS(deep learning dock virtual screening)by using deep learning models(regression and classification models)to learn the outcomes of pipelined docking programs step-by-step.Results:In this study,we showed that this approach could successfully weed out compounds with poor docking scores while keeping compounds with potentially high docking scores against 10 DUD-E protein targets.A self-built dataset of about 1.9 million molecules was used to further verify DL-DockVS,yielding good results in terms of recall rate,active compounds enrichment factor and runtime speed.Conclusions:We comprehensively evaluate the practicality and effectiveness of DL-DockVS against 10 protein targets.Due to the improvements of runtime and maintained success rate,it would be a useful and promising approach to screen ultra-large compound libraries in the age of big data.It is also very convenient for researchers to make a well-trained model of one specific target for predicting other chemical libraries and high docking-score molecules without docking computation again.