Postbuckling analysis of ultra-low rigidity serpentine structures

Serpentine structures are of growing interest due to its unique mechanical and physical properties for applications in stretchable electronics, mechanical sensing, biomedical devices. Mechanics-guided, deterministic three-dimensional (3D) assembly provide routes to form remarkable 3D structures, which in turn significantly improve its potential for applications. Therefore, an accurate postbuckling analysis is essential to the complex 3D serpentine structures with arbitrary geometry/material parameters. Here, simple, analytical expressions are obtained for the displacement and effective rigidity of serpentine structures during postbuckling. By tuning geometry parameters, the amplitude of assembled 3D serpentine structures can span a very broad range from zero to that of a straight ribbon. The analytical model can be used in design, fabrication, and application of versatile 3D serpentine structures to ensure their compatibility with the ultra-low rigidity biological tissues. A hierarchical 3D serpentine structure with ultra-low rigidity is presented to demonstrate the application of the analytical model.

Discovery of key function module in complex mechanical 3D CAD assembly model for design reuse

Purpose Complex mechanical 3D computer-aided design (CAD) model embodies rich implicit design knowledge. Through discovering the key function parts and key function module in 3D CAD assembly model in advance, it can promote the designers’ understanding and reuse efficiency of 3D assembly model in design reuse. Design/methodology/approach An approach for discovering key function module in complex mechanical 3D CAD assembly model is proposed. First, assembly network for 3D CAD assembly model is constructed, where the topology structure characteristics of 3D assembly model are analyzed based on complex network centrality. The degree centrality, closeness centrality, betweenness centrality and mutual information of node are used to evaluate the importance of the parts in 3D assembly model. Then, a multi-attribute decision model for part-node importance is established, and the comprehensive evaluation for key function parts in 3D assembly model is accomplished by combining Analytic Hierarchy Process and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). Subsequently, a community discovery of function module in assembly model-based Clauset–Newman–Moore (CNM)-Centrality is given in details. Finally, 3D CAD assembly model of worm gear reducer is taken as an example to verify the effectiveness and feasibility of proposed method. Findings The key function part in CAD assembly model is evaluated comprehensively considering assembly topology more objectively. In addition, the key function module containing key function part is discovered from CAD assembly model by using CNM-Centrality-based community discovery. Practical implications The approach can be used for discovering important design knowledge from complex CAD assembly model when reusing the assembly model. It can help designers capture and understand the design thinking and intent, improve the reuse efficiency and quality. Originality/value The paper first proposes an approach for discovering key function module in complex mechanical 3D CAD assembly model taking advantage of complex network theory, where the key function part is evaluated using node centrality and TOPSIS, and the key function module is identified based on community discovery.

Research on key technology of 3D digitization for secondary system of power grid based on model application analysis

In order to solve the problems of long development time, poor expansibility and small application scope in the digital design of secondary system of intelligent substation at present, this paper puts forward the 3D assembly techniques based on the expanded model by analyzing the integration of secondary model files of intelligent substation. In the design process of this method, the relationship between primary equipment and secondary equipment, the mapping between logical circuit and real circuit are fully considered. By using standard family library techniques, file analysis techniques and automatic mapping techniques, the coupling between physical model and logical relationship is realized. Taking the actual 220kV intelligent substation as the pilot, the three-dimensional model in secondary system simulation analysis, online monitoring and the application of fault diagnosis shows that the techniques can effectively improve the efficiency of three-dimensional design and maintenance of secondary system.

Optimization of the Fluidic-Based Assembly for Three-Dimensional Construction of Multicellular Hydrogel Micro-Architecture in Mimicking Hepatic Lobule-like Tissues

Three-dimensional (3D) assembly of microstructures encapsulating co-cultured multiple cells can highly recapitulate the in vivo tissues, which has a great prospect in tissue engineering and regenerative medicine. In order to fully mimic the in vivo architecture, the hydrogel microstructure needs to be designed into a special shape and spatially organized without damage, which is very challenging because of its limited mechanical properties. Here, we propose a 3D assembly method for the construction of liver lobule-like microstructures (a mimetic gear-like microstructure of liver lobule) through the local fluidic interaction. Although the method has been proven and is known as the consensual means for constructing 3D cellular models, it is still challenging to improve the assembly efficiency and the assembly success rate by adjusting the fluidic force of non-contact lifting and stacking. To improve the assembly efficiency and the assembly success rate, a fluidic simulation model is proposed based on the mechanism of the interaction between the microstructures and the fluid. By computing the simulation model, we found three main parameters that affect the assembly process; they are the velocity of the microflow, the tilt angle of the manipulator and the spacing between the microstructures and the manipulator. Compared with our previous work, the assembly efficiency was significantly improved 63.8% by using the optimized parameters of the model for assembly process, and the assembly success rate was improved from 98% to 99.5%. With the assistance of the assembly simulation, the luminal 3D micromodels of liver tissue show suitable bioactivity and biocompatibility after long-term hepatocytes culture. We anticipate that our method will be capable of improving the efficiency of the microstructures assembly to regenerate more complex multicellular constructs with unprecedented possibilities for future tissue engineering applications.

Redesign of protein nanocages: the way from 0D, 1D, 2D to 3D assembly

This review focuses on the design and construction of artificial protein nanocages, and their assembly into highly ordered supramolecules.

A Novel Method for Characterization of Ultralow Viscosity NCF Layers Using TCB for 3D Assembly

For die-to-wafer (D2W) stacking of high-density interconnects and fine-pitch microbumps, underfill serves to fill the spaces in-between microbumps for protection and reliability. Among the different types of underfill, nonconductive film (NCF) has the advantages of fillet and volume control. However, one of the challenges is the solder joint wetting. An NCF must have good embedded-flux activation to mitigate Cu UBM pad oxidation due to the repeated TCB cycles that accelerate oxidation on neighboring dice. The flux in the NCF also helps in wetting the solder bumps. To realize efficient solder wetting, one must also understand the NCF deformation quality, which is a function of its viscosity. This parameter has direct impact on the deformation of solder bumps. High-viscosity NCF would be difficult to deform, thus preventing solder contact to pad during TCB reflow temperature. High bond force is required and could lead to reduced alignment accuracy. For a low viscous NCF, it requires low bond force. Solder joint wetting is a challenge with excessive squeezeout due to fast and instantaneous deformation. We seek to demonstrate in this article a creative methodology for NCF material characterization, considering the factors of NCF viscosity, deformation, and solder squeezeout. We use TCB tool position-tracking data to define the deformation curve of the NCF as a function of temperature and time at very fast profile of TCB. We use the NCF viscosity curve as reference in relation to the actual deformation, and predict dynamic deformation in three different configurations. Deformation test configurations were performed on chips with and without microbumps bonded with a rigid flat glass surface and with a bottom Cu UBM pad. The experiments were performed with different heating ramp rates at target above Sn reflow of ~250°C interface temperature. As validation, we applied the optimized TCB process (force, temperature, and ramp rate) on a test vehicle with 20 and 40 μm pitch daisy chains and obtained very good connectivity with good joint and IMC formation.

Crystal capillary origami capsule with self-assembled nanostructures

Self-assembling mechanism of elasto-capillary opens new applications in micro and nanotechnology by providing 3D assembly structures with 2D planar unit cells, so-called capillary origami. To date, the final structure has...

Towards 3D self-assembled rolled multiwall carbon nanotube structures by spontaneous peel off

Controlling the 3D assembly of individual nanomaterials can be a challenging task. However, it opens up opportunities for the production of increasingly complex nanostructures. Unusual rolled multiwall carbon nanotube structures are synthesized here by simply inducing a change of precursor composition during the growth of multiwall carbon nanotube forests. The multiwall carbon nanotube structures are comprised of nitrogen-doped and undoped sections, and are obtained via a detailed peel off and roll mechanism. These results open new doors for the development of increasingly complex nanostructures.