Mingke Li and Wangyu Liu
The purpose of this paper is to present the novel parameterized digital-mask generation method which is aimed at enhancing bio-scaffold’s fabricating efficiency with digital…
Abstract
Purpose
The purpose of this paper is to present the novel parameterized digital-mask generation method which is aimed at enhancing bio-scaffold’s fabricating efficiency with digital micro-mirror device (DMD)-based systems.
Design/methodology/approach
A method to directly generate the digital masks of bio-scaffolds without modeling the entire 3D scaffold models is presented. In most of the conventional methods, it is inefficient to dynamically modify the size of the structural unit cells during design, because it relies more or less on commercial computer aided design (CAD) platforms. The method proposed in this paper can achieve high efficient parameterized design, and it is independent from any CAD platforms. The generated masks in binary bitmap format can be used by the DMD-based to achieve scaffold’s additive manufacture. In conventional methods, the Boolean operation of the external surface and the internal architectures would result in the damage of unit cells in boundary region. These damaged unit cells not only lose its original mechanical property but also cause numbers of gaps and isolated features that would reduce the geometric accuracy of the fabricated scaffolds; the proposed method in this paper provides an approach to tackle this defect.
Findings
The results show that the proposed method can improve the digital masks generation efficiency.
Practical implications
The proposed method can serve as an effective supplement to the slicing method in additive manufacture. It also provides a way to design and fabricate scaffolds with heterogeneous architectures.
Originality/value
This paper gives supports to fabricate bio-scaffold with DMD-based systems.
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Wangyu Liu, Dong Sun, Aimin Tang and Mingke Li
Hydrogel is an excellent material for the fabrication of porous scaffold by mask-prototyping method. Different from the common commercial resin, hydrogel is hydrophilic and…
Abstract
Purpose
Hydrogel is an excellent material for the fabrication of porous scaffold by mask-prototyping method. Different from the common commercial resin, hydrogel is hydrophilic and hyperelastic, so that it cannot bear the conventional post-curing process to improve its mechanical properties. The purpose of this paper is to put forward a method to improve the curing bonding strength at the weak juncture of the porous hydrogel scaffold.
Design/methodology/approach
The working curve of the resin was obtained through the single layer cure experiment, and the energy accumulation model has been set up by MATLAB. Aimed at the specificity of material, a new method of partial curing on different kind of structure has been proposed. Under the same condition, only the tn2 needs to be changed to fabricate different test specimens with different accumulated energy between two layers. The tensile test is carried out with the authors’ preferred equipment.
Findings
The analysis reveals that accumulated energy can be changed by adjusting the key parameters, and the tensile test shows that when the accumulated energy is bigger, the ultimate tensile strength is higher.
Research limitations/implications
Subject to the equipment accuracy and specificity of material, some errors coming from the experiment and test might exist, but the authors believe they will not change their findings and conclusions in this paper.
Practical implications
The research provides a method which is different from the common methods but friendlier to improve the bonding strength of the hydrogel scaffold.
Social implications
This work can help to adjust the mechanical property of the scaffold used in tissue engineering.
Originality/value
This method can improve the bonding strength at weak juncture and give a direction for the design of porous scaffold.
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Aimin Tang, Qinwen Wang, Shan Zhao and Wangyu Liu
Nanocellulose is characterised by favourable biocompatibility, degradability, nanostructure effect, high modulus and high tensile strength and has been widely applied in various…
Abstract
Purpose
Nanocellulose is characterised by favourable biocompatibility, degradability, nanostructure effect, high modulus and high tensile strength and has been widely applied in various fields. The current research in the field of new nanocellulose materials mainly focuses on the hydrogel, aerogel and the tissue engineering scaffold. All of these are three-dimensional (3D) porous materials, but conventional manufacturing technology fails to realise precise control. Therefore, the method of preparing structural materials using 3D printing and adopting the nanocellulose as the 3D printing material has been proposed. Then, how to realise 3D printing of nanocellulose is the problem that should be solved.
Design/methodology/approach
By adding the photosensitive component polyethyleneglycol diacrylate (PEGDA) in the aqueous dispersion system of nanocellulose, the nanocellulose was endowed with photosensitivity. Then, nanocellulose/PEGDA hydrogels were prepared by the additive manufacturing of nanocellulose through light curing.
Findings
The results showed that the nanocellulose/PEGDA hydrogels had a uniform shape and a controllable structure. The nanocellulose supported the scaffold structure in the hydrogels. Prepared with 1.8 per cent nanocellulose through 40 s of light curing, the nanocellulose/PEGDA hydrogels had a maximum compression modulus of 0.91 MPa. The equilibrium swelling ratio of the nanocellulose/PEGDA hydrogel prepared with 1.8 per cent nanocellulose was 13.56, which increased by 44 per cent compared with that of the PEGDA hydrogel without nanocellulose.
Originality/value
The paper proposed a method for rapidly prototyping the nanocellulose with expected properties, which provided a theoretical basis and technological reference for the 3D additive manufacturing of nanocellulose 3D structure materials with a controlled accurate architecture.
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Wangyu Liu and Mingke Li
This paper aims to propose the new two-step adaptive direct slicing method for building bio-scaffold with digital micro-mirror device (DMD)-based MPμSLA systems.
Abstract
Purpose
This paper aims to propose the new two-step adaptive direct slicing method for building bio-scaffold with digital micro-mirror device (DMD)-based MPμSLA systems.
Design/methodology/approach
In this paper, the authors proposed a new approach to directly slice a scaffold’s CAD model (i.e the three-dimensional model built by computer-aided design platforms) and save the slices’ data as BMP (bitmap, i.e. the data format used in DMD) files instead of other types of two-dimensional patterns as an intermediary. The proposed two-step strategy in this paper, i.e. a CAD model’s exterior surface and internal architecture were sliced, respectively, at first, and then assembled together to obtain one intact slice. The assembly process is much easier and convenient based on the slice data in BMP format. To achieve the adaptive slicing for both the exterior part and internal part, two new indices, the exterior surface-dominated index and internal architecture-dominated index, are, respectively, utilized as the error estimation indices. The proposed approach in this paper is developed on SolidWorks platform, but it can also be implemented on other platforms.
Findings
The authors found that the approach is not only more accurate but also more efficient by avoiding the repeated running of those inefficient rasterization programs. The approach is able to save computer resource and time, and enhance the robustness of slicing program, as well as is appropriate for the scaffolds’ model with internal pore architecture and external free-form surface.
Practical implications
Bio-scaffolds in tissue engineering require precise control over material distribution, such as the porosity, connectivity, internal pore architecture and external free-form surface. The proposed two-step adaptive direct slicing approach is a good balance of slicing efficiency and accuracy and can be useful for slicing bio-scaffolds’ models.
Originality/value
This paper gives supports to build bio-scaffold with DMD-based MPμSLA systems.
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Yu Wang, Daqing Zheng and Yulin Fang
The advancement of enterprise social networks (ESNs) facilitates information sharing but also presents the challenge of managing information boundaries. This study aims to explore…
Abstract
Purpose
The advancement of enterprise social networks (ESNs) facilitates information sharing but also presents the challenge of managing information boundaries. This study aims to explore the factors that influence the information-control behavior of ESN users when continuously sharing information.
Design/methodology/approach
This study specifies the information-control behaviors in the “wall posts” channel and applies communication privacy management (CPM) theory to analyze the effects of the individual-specific factor (disposition to value information), context-specific factors (work-relatedness and information richness) and risk-benefit ratio (public benefit and public risk). Data on actual information-control behaviors extracted from ESN logs are examined using multilevel mixed-effects logistic regression analysis.
Findings
The study's findings show the direct effects of the individual-specific factor, context-specific factors and risk-benefit ratio, highlighting interactions between the individual motivation factor and ESN context factors.
Originality/value
This study reshapes the relationship of CPM theory boundary rules in the ESN context, extending information-control research and providing insights into ESNs' information-control practices.
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Haiyang Hu, Yu Wang, Chenchen Lian and Peiyan Wang
In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method…
Abstract
Purpose
In this paper, an attempt is made to obtain buckling loads, ultimate bearing capacity and other required structural characteristics of grid structure panels. The numerical method for post-buckling behavior analysis of panels involving multiple invisible damages is also presented.
Design/methodology/approach
In this paper, two bidirectional stiffened composite panels are manufactured and tested. Multiple discrete invisible damages are introduced in different positions of the stringers, and the experimental and simulation investigation of buckling and post-buckling were carried out on the damaged stiffened panels.
Findings
The simulation load–displacement curves are compared with the experimental results, and it is found that the simulation model can well predict the occurrence of buckling and failure loads. The strain curve shows that the rate of strain change at the damaged site is greater than that at the undamaged site, which reflects that the debond is more likely occurred at the damaged site. The simulation verifies that the panel is usually crushed due to matrix compression and fiber–matrix shear.
Originality/value
In this paper, post-buckling tests and numerical simulations of bidirectional stiffened composite panels with impact damage were carried out. Two panels with four longitudinal stringers and two transverse stringers were manufactured and tested. The buckling and post-buckling characteristics of the grid structure are obtained, and the failure mechanism of the structure is explained. This is helpful for the design of wall panel structure.
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This chapter is a narrative account of a Ford Foundation sponsored project from mid-2005 through 2008 for investigating into the causes and engineering a solution to the migrant…
Abstract
This chapter is a narrative account of a Ford Foundation sponsored project from mid-2005 through 2008 for investigating into the causes and engineering a solution to the migrant workers education access problems in manufacturing areas in Shanghai, China. The project team was comprised of faculty members and students from East China Normal University, consulted by two professors from Columbia University. This chapter describes how the team arrived at a solution to the problem by investigating the problems, socializing with the migrant workers, and doing experiments that helped us to make adjustments on the proposed solution from time to time. Unlike the popular understanding of the educational needs of the migrant workers that the workers just need some short-term training for a job, our finding is that the workers need degree and certificate programs too. They need further education for personal and career development, not just a job that can feed them. The workers are Internet fans too, most of those who want further education would prefer a blended learning. We ran quite a few courses and a learning center to observe the learning behavior of the workers, which allowed us to actually interact with the workers and see how they respond to our experimental stimuli. While most of the migrant workers show an interest in learning, we did not observe much active learning involvement of the migrant workers. We identified seven factors that limit access to learning engagement: (1) inadequate transportation means; (2) very long work days and weeks and irregular shifts; (3) difficult living conditions; (4) restricted computer and Internet access; (5) inaccessibility of information; (6) unsupportive social environment; (7) lack of educational infrastructure. As a solution to the identified problem, we propose a learning center based community college network in all the manufacturing areas. A learning center serves as a social learning incubator to nurture the learning practices of the academically less prepared learner, the migrant workers.