The Properties of an UV Curable Support Material Pre-polymer for Three Dimensional Printing

An ultraviolet（UV） curable support material pre-polymer for three dimensional printing was prepared based on the synergistic effect between PEO-PPO-PEO tri-block copolymer（F127） and polyethylene glycol （400） di-acrylate（SR344）. The effects of jetting conditions, thermal stability, curing time, mechanical properties and shrinking rate on printing models were studied. The situation of removing support material from build model was investigated after building progress was completed. The experimental result shows that when F127 is 6.0wt%, SR344 is 20.0wt%, 4-Methoxy phenol is 0.15wt% and Irgacure 2959 is 1.5wt%, the support material pre-polymer could be jetted out from the nozzles smoothly during building up of three dimensional printing models at 50-55 ℃. In addition, the support material could be removed easily from building model without spoiling the model; furthermore, the forming precision of building model is improved.

Part Orientation Optimization in Three Dimensional Printing

Part orientation is one of the important factors in manufacturing with three dimensional printing (3DP) of rapid prototyping system. The minimum building time, being achieved by the part’s minimum building height and minimum width in 3DP’s y direction, is set as the objective of optimizing the part orientation. Genetic algorithm is adopted to find the minimum building height of parts and then ergodic searching is used to get the minimum width of part in y direction. A corresponding program for optimizing part orientation in 3DP was developed. Tests show the proposed approach is effective and fast.

Impact of three dimensional printing in orthopedics

The primary objective of this article is to explore effects of latest development in the area of three dimensional(3D)printing&to assess its abilities,and further undertake helpful reporting.Here the focus is to assess ad vantages of 3D printing in orthopedics and analyze how 3D printed models help solve complex 3D orthopedics distortions.This study identified that 3D models manufactured by 3D printing models reduce medical parts de velopment cost and surgical planning time.Integrating 3D printing with orthopaedics helps in understanding the conditions of problems and achieving the operation succssfully.This technology can enable doctors/surgeons to design,produce,recreate and plan operations more accurately,carefully,and economicaly.3D models can assist specialists with a visual comprehension of the patient-particular pathology and life structures.Innovation in 3D printing initiated a scaffold for the virtual outline and execution of medical procedures.This research proposes the utilisation of 3D printers as an elective procedure for the fabrication of parts.It empowers surgeons/patients for better raining,education and research.In the future,there is a foreseeable expansion of additive manufacturing in orthopedics.

Use of three dimensional-printing in the management of floating aortic thrombus due to occult aortic dissection:A case report

BACKGROUND Floating thrombus within the thoracic aorta is a rare entity but may cause systemic embolism.The pathogenesis of floating aortic thrombi is not yet fully understood.No definitive guidelines are available for the management of floating aortic thrombus.CASE SUMMARY We report a 48-year-old patient,without a history of trauma and infection,who presented with sudden severe back pain.A floating thrombus within the aortic arch was found by computed tomography angiography(CTA).No evidence of coagulopathies was found.However,with the assistance of a three dimensionalprinted model,this floating thrombus was identified to be caused by occult aortic dissection(AD).Subsequently,an emergency thoracic endovascular repair was performed.The patient’s back pain was rapidly alleviated postoperatively.CTA at 1 year showed no filling defect in the stent-graft and aorta.CONCLUSION Occult AD is a potential factor causing floating aortic thrombi,endovascular stent-graft exclusion may be an optimal therapeutic choice with promising results.Moreover,the combination of CTA and three dimensional-printed models can contribute to the diagnosis and treatment of floating aortic thrombi due to occult AD.

Advances in Study on Three-dimensional Printing in Pharmaceutics

Three dimensional printing（3DP） is a solid freeform fabrication technology which employs powder processing and a liquid binder material in the construction of parts in a layer-wise manner. 3DP can accommodate much geometric outline and be made with many materials due to its unprecedented flexibility. The technology can control over the material composition, microstructure and surface texture so it attracts great attentions in the pharmaceutics field. 3DP can offer many novel strategies and approaches for the research and is widely focused in the field of the controlled-release drug delivery systems. Through consulting a large number of documents the current development and the technical characteristics of 3DP in pharmaceutics field are discussed and reviewed. It is expected that 3DP technique may play a tremendous role in pharmaceutics field in the future.Three dimensional printing （3DP） is a solid freeform fabrication technology which employs powder processing and a liquid binder material in the construction of parts in a layer-wise manner. 3DP can accommodate much geometric outline and be made with many materials due to its unprecedented flexibility. The technology can control over the material composition, microstructure and surface texture so it attracts great attentions in the pharmaceutics field. 3DP can offer many novel strategies and approaches for the research and is widely focused in the field of the controlled-release drug delivery systems. Through consulting a large number of documents the current development and the technical characteristics of 3DP in pharmaceutics field are discussed and reviewed. It is expected that 3DP technique may play a tremendous role in pharmaceutics field in the future.

Preliminary 3D printing of large inclined-shaped alumina ceramic parts by direct ink writing

Three dimensional(3D)printing technology by direct ink writing(DIW)is an innovative complex shaping technology,possessing advantages of flexibility in fabrication,high efficiency,low cost,and environmental-friendliness.Herein,3D printing of complex alumina ceramic parts via DIW using thermally induced solidification with carrageenan swelling was investigated.The rheological properties of the slurry under different thermally-induced modes were systematically studied.The solidification properties of thermally-induced pastes with varying contents of carrageenan were optimized.The experimental results showed that the optimized paste consisting of 0.4 wt%carrageenan could be rapidly solidified at about 55℃,which could print inclined-plane more than 60°in vertical without support,resulting in better homogeneity of the green body.A nearly pore-free structure was obtained after sintering at 1600℃ for 2 h.

Multi-Object Optimal Design of Rapid Prototyping Based on Uniform Experiment

Experiment of rapid prototyping (RP) is a multi-level and multi-factor problem with long process cycle. As powder-based RP method, three dimensional printing (3DP), and selective laser sintering (SLS) are the most prominent RP methods for their flexibility in material selecting. The research of 3DP process shows that much experiments work can be greatly decreased by the method of uniform design with restricted mixtures for RP products’ performance to its forming material. Then, according to backward regression methods, the binomial and inverse terms nonlinear regression equations were set up by statistic analysis and computation. Together with evaluation function method, multi-object optimization model for performance of products to the powder mixtures was developed, and the optimization problem was solved by software MATLAB. After that, the optimum results were solved and tested by experiment with the same condition as before. Differences between the calculation results and testing results, which including product’s density, compression strength, surface evaluation, and deformation in three dimensions, are less than 10%, and have the same error direction. Uniform design method for regression and optimization was proved to be an excellent method to obtain optimum results for multi-level and multi-factor experiments of RP and other process which have a long processing cycle.

Experimental investigation on the deformation characteristics of locking-steel-pipe(LSP)pile retaining structure during excavation in sand

Locking-steel-pipe(LSP)piles connect with adjacent joints to form a pile row enclosure structure.Due to the advantages of quick construction,efficiency in installation,and recycle utilization,the connected LSP piles are frequently used as retaining structure in deep excavation.However,systematic studies of the deformation mechanism of the LSP pile retaining structure are rarely reported,and it still lack of experimental evidence to optimize the design.In this study,a braced supported excavation experimental model test in sand was designed and conducted to investigate the deformation characteristics of LSP pile retaining structure.Three dimensional(3D)printing technique was creatively applied to manufacture LSP model piles.The experimental results show that,a“S”shaped distribution of bending moments is observed along pile shaft when excavation is executed;the deflection of pile shaft develops deep-seated movements toward the excavation side as excavation went deeper,resulting in a“bowl”ground settlement.With the deflection of LSP piles,a rotating trend was occurred between pairs of locking joint,and the severe open deformation of locking joint arose on excavation side.There was a gradual reduction in earth pressure behind the LSP pile retaining wall with excavation depth.The earth pressure between two struts level had no obvious changing,owing to the supported effect of inner struts.