Xuan Song

Biomimetic Anisotropic Reinforcement Architectures by Electrically Assisted Nanocomposite 3D Printing

Biomimetic architectures with Bouligand-type carbon nanotubes are fabricated by an electrically assisted 3D-printing method. The enhanced impact resistance is attributed to the energy dissipation by the rotating anisotropic layers. This approach is used to mimic the collagen-fiber alignment in the human meniscus to create a reinforced artificial meniscus with circumferentially and radially aligned carbon nanotubes.

Equilibrium Design Based on Design Thinking Solving: An Integrated Multicriteria Decision-Making Methodology

A multicriteria decision-making model was proposed in order to acquire the optimum one among different product design schemes. VIKOR method was introduced to compute the ranking value of each scheme. A multiobjective optimization model for criteria weight was established. In this model, projection pursuit method was employed to identify a criteria weight set which could keep classification information of original schemes to the greatest extent, while PROMETHEE II was adopted to keep sorting information. Dominance based multiobjective simulated annealing algorithm (D-MOSA) was introduced to solve the optimization model. Finally, an example was taken to demonstrate the feasibility and efficiency of this model.

Piezoelectric component fabrication using projection-based stereolithography of barium titanate ceramic suspensions

Purpose Conventional machining methods for fabricating piezoelectric components such as ultrasound transducer arrays are time-consuming and limited to relatively simple geometries. The purpose of this paper is to develop an additive manufacturing process based on the projection-based stereolithography process for the fabrication of functional piezoelectric devices including ultrasound transducers. Design/methodology/approach To overcome the challenges in fabricating viscous and low-photosensitive piezocomposite slurry, the authors developed a projection-based stereolithography process by integrating slurry tape-casting and a sliding motion design. Both green-part fabrication and post-processing processes were studied. A prototype system based on the new manufacturing process was developed for the fabrication of green-parts with complex shapes and small features. The challenges in the sintering process to achieve desired functionality were also discussed. Findings The presented additive manufacturing process can achieve relatively dense piezoelectric components (approximately 95 per cent). The related property testing results, including X-ray diffraction, scanning electron microscope, dielectric and ferroelectric properties as well as pulse-echo testing, show that the fabricated piezo-components have good potentials to be used in ultrasound transducers and other sensors/actuators. Originality/value A novel bottom-up projection system integrated with tape casting is presented to address the challenges in the piezo-composite fabrication, including small curing depth and viscous ceramic slurry recoating. Compared with other additive manufacturing processes, this method can achieve a thin recoating layer (as small as 10 μm) of piezo-composite slurry and can fabricate green parts using slurries with significantly higher solid loadings. After post processing, the fabricated piezoelectric components become dense and functional.

Joint Design for 3-D Printing Non-Assembly Mechanisms

The layer-based additive manufacturing (AM) processes can directly fabricate sub-systems with multiple components during the building process. Novel applications in robotics and many others have been demonstrated by removing the need of component assembly. However, the AM processes also have inferior accuracy compared to the Computer Numerical Control (CNC) machining process. Hence the joint clearance that can be achieved in a 3D-printed mechanism is large. This would significantly limit the use of AM in directly building movable sub-systems without further assembly operations after the building process. To reduce the joint clearance, we present a novel joint design by considering the fabrication limitation of AM processes. A novel marker structure is developed for various types of joints including cylindrical pin joints. The relation of the marker design and the rotation performance of the 3D-printed joint is modeled. Test cases based on the Stereolithography Apparatus (SLA) process have been performed to verify the effectiveness of the developed joint design. Compared to the traditional pin joint design, the new design can achieve a smaller clearance during rotation while still be able to be fabricated by the SLA process. Consequently its rotation performance can be improved.Copyright

Robust engineering: improved inductive design exploration approach to bionic system

Abstract Multidimensional space biomimetic information of space variables is acquired by evaluating bionic degree indices of them. According to bionic degree of each space variable, comprehensive hyperdimensional error margin index in variable space is defined to characterise bionic robustness of discrete points in input space based on inductive design exploration method. Feasible point checking equation is established, which considers differences between space variables, to further reduce target dimensions in optimisation and distinguish variables with different bionic degree. Compromise decision support problem method is used to identify the best solution from the subset using deviation of comprehensive hyperdimensional error margin index in each output space as objective function.

Recent Progress in Biomimetic Additive Manufacturing Technology: From Materials to Functional Structures

Nature has developed high-performance materials and structures over millions of years of evolution and provides valuable sources of inspiration for the design of next-generation structural materials, given the variety of excellent mechanical, hydrodynamic, optical, and electrical properties. Biomimicry, by learning from natures concepts and design principles, is driving a paradigm shift in modern materials science and technology. However, the complicated structural architectures in nature far exceed the capability of traditional design and fabrication technologies, which hinders the progress of biomimetic study and its usage in engineering systems. Additive manufacturing (three-dimensional (3D) printing) has created new opportunities for manipulating and mimicking the intrinsically multiscale, multimaterial, and multifunctional structures in nature. Here, an overview of recent developments in 3D printing of biomimetic reinforced mechanics, shape changing, and hydrodynamic structures, as well as optical and electrical devices is provided. The inspirations are from various creatures such as nacre, lobster claw, pine cone, flowers, octopus, butterfly wing, fly eye, etc., and various 3D-printing technologies are discussed. Future opportunities for the development of biomimetic 3D-printing technology to fabricate next-generation functional materials and structures in mechanical, electrical, optical, and biomedical engineering are also outlined.

3D printing of piezoelectric transducer/array for ultrasonic imaging

Piezoelectric ceramics are currently of considerable interest for their capabilities of converting compressive/tensile stresses to an electric charge, or vice versa. The applications of piezoelectric devises are far reaching, ranging from acoustic imaging to energy harvesting. However, conventional manufacturing processes such as etching and dicing for piezoelectric ceramics fabrication have limited capability of achieving complex geometry. Because ceramics cannot be cast and machined easily, additive manufacturing (AM) processes (3D printing technology) are considered as a promising way in novel piezoelectric devices. This article presents piezoelectric element/array with complex geometry, fabricated by Mask-Image-Projection-based Stereolithography (MIP-SL) technology.

Piezoelectric array for transducer application using additive manufacturing

Piezoelectric ceramic and the corresponding array are widely used in energy harvesting and ultrasonic application for the capabilities of converting compressive/tensile stresses to an electric charge, or vice versa. However, the need for a complex geometry of array is a major technical challenge for further application. To enable the fabrication of piezoelectric ceramics, additive manufacturing (AM) processes (3D printing technology) is expect. In this study, we propose a Mask-Image-Projection-based Stereolithography (MIP-SL) technology to print piezoelectric-composite slurry with BaTiO3 particles into different arrays. After post-process, the printed arrays display piezoelectric properties that can be used in ultrasonic application.

A Stereolithography-Based Sugar Foaming Method for Porous Strucutre Fabrication

Porous structure has wide application in industry, thanks to some of its special properties such as low density, low thermal conductivity, high surface area and efficient stress transmission. Both templating and foaming agent methods are used to fabricate porous structures. However, these methods can only produce simple geometries. In recent years, many research studies have been done to use additive manufacturing (AM), e.g. stereolithography (SLA), in the fabrication of porous structure, but the porosity that can be achieved is relatively small due to their limited accuracy in building micro-scale features on a large area. This paper presents a projection based SLA process to fabricate porous polymer structures using sugar as the foaming agent. With a solid loading of 50wt% of the sugar in the resin, the method can achieve a porosity over 50%. This method can be used to increase the porosity achieved by current SLA methods by over 100%.Copyright