In-mould graining of 3D-shaped parts with micro-structured surfaces

2016 ◽  
Vol 36 (6) ◽  
pp. 583-588
Author(s):  
Christian Hopmann ◽  
Jonathan Martens
Keyword(s):  
Three Dimensional ◽  
Rheological Behaviour ◽  
Functional Surface ◽  
Structured Surfaces ◽  
Conflict Of Interests ◽  
Cycle Times ◽  
Processed Material ◽  
Side Walls ◽  
Plastic Components ◽  
Micro Structures

Abstract To make functional surface effects on plastic components usable on an industrial scale, new processes have to be developed. The in-mould graining (IMG) process is a variant of the thermoforming enabling the manufacture of micro-structures. One advantage of the IMG process is that the surface structure is formed to the final shape of the part. Recent investigations show that the forming accuracy of a flat mould can be extended by applying a variothermal mould heating in the IMG process. As high mould temperatures lead to high forming accuracies but also increase the cycle time of the process, a conflict of interests follows. In this paper, it is investigated to what extent high moulding accuracies can be achieved to form three-dimensional parts by using the IMG process extended by a variothermal mould heating. The results show that forming accuracies of micro-scaled structures of >90% can be reached on the bottom and the side walls of a cup-shaped mould. To address the conflict of interests between high moulding accuracy and long cycle times, the influence of the mould temperature is investigated in detail. To analyse the micro-forming behaviour of the processed material, analyses of the rheological behaviour with a rotational rheometer are carried out.

FEM-Based Analysis of Micro-Structure Parameters for Roll Forming on Aluminum Alloy Sheet

2013 ◽  
Vol 762 ◽  
pp. 763-768
Author(s):  
Zhi Qing Hu ◽  
Ji Zhao ◽  
Zeng Ming Feng
Keyword(s):  
Three Dimensional ◽  
Alloy Sheet ◽  
Roll Forming ◽  
Micro Structure ◽  
Structured Surfaces ◽  
Micro Patterning ◽  
Dimensional Finite Element ◽  
Marine Applications ◽  
Three Dimensional Finite Element ◽  
Micro Structures

Micro-structured surfaces with drag reduction, desorption, and excellent optical performance are widely used in the field of automotive, aerospace, marine applications. Therefore, the manufacturing of the micro-structure on the metal surface is of high impotance. Although the processing methods for micro-patterning of surfaces have progressed in recent years, micro-structure processing is still not used on large metal surfaces. In this paper, a method of roll forming micro-structure on the plate surface is proposed. A simulation model for micro-structure roll forming (MRF) was presented by using three-dimensional finite element method (FEM). The strain and stress, and the displacements caused by micro-structure were analyzed. The results provide theoretical guidance for the design of different micro-structures and the sequence of their processing.

scholarly journals Vibration welding of components with angled areas in the direction of vibration

2020 ◽  
Vol 64 (11) ◽  
pp. 1843-1853
Author(s):  
Sascha Vogtschmidt ◽  
Isabel Fiebig ◽  
Volker Schoeppner
Keyword(s):  
Weld Seam ◽  
Three Dimensional ◽  
High Energy ◽  
Weld Strength ◽  
Short Cycle ◽  
Cycle Times ◽  
Linear Movement ◽  
Vibration Welding ◽  
Plastic Components ◽  
Design Freedom

Abstract Conventional manufacturing processes for plastic products, such as injection molding or extrusion, often limit the achievable component geometries. Therefore, it is necessary to join components in order to generate highly complex geometries. Vibration welding is one way of joining components. This process is frequently used and is characterized by short cycle times, high energy efficiency, and the possibility of joining large components. In vibration welding, plastic components are heated by an oscillating friction movement of the joining surfaces, then plasticized and subsequently welded together. The joining of three-dimensional seam geometries is therefore a challenge for vibration welding, as the components can be lifted off by the linear movement and the surfaces do not plasticize sufficiently. Previous investigations have shown that angles of up to 20° can be welded in the direction of vibration, but that the deviation from the plane considerably reduces the weld strength. In order to weld three-dimensional weld seam geometries with short cycle times and simultaneously achieve a high weld seam strength, a process is being developed which is intended to extend the design freedom in vibration welding.

Solid and Hollow Micro and Nano Spherical Structures: in Polysilicon and Phosphosilicate Glass

1994 ◽  
Vol 372 ◽  
Author(s):  
M. M. Farooqui ◽  
A. G. R. Evans
Keyword(s):  
Ion Beam ◽  
Three Dimensional ◽  
Optical Components ◽  
Circular Symmetry ◽  
Spherical Structures ◽  
Phosphosilicate Glass ◽  
Micro Systems ◽  
Micro Structures ◽  
Microfabrication Techniques

Fabrication of three dimensional micro structures in silicon and silicon related materials is becoming increasingly important for the realisation of micro systems comprising of sensors, actuators, transducers and analytical assemblies. Fabrication of such devices so far has been mostly in form of structures defined by the crystal planes of silicon, or has involved sophisticated technologies such as ion beam machining, replication using LIGA, or micromachining techniques involving a sequence of alignment and etch stages using binary masks. Structures with circular symmetry are of great interest as micro optical components amongst others, and these are not easily amenable to microfabrication techniques commonly employed.

scholarly journals Modelling Polycrystalline Materials: An Overview of Three-Dimensional Grain-Scale Mechanical Models

2013 ◽  
Vol 05 (01) ◽  
pp. 1350002 ◽  
Author(s):  
I. Benedetti ◽  
F. Barbe
Keyword(s):  
Three Dimensional ◽  
Constitutive Modelling ◽  
Polycrystalline Materials ◽  
High Fidelity ◽  
Computational Capability ◽  
Mechanical Models ◽  
Three Dimensional Models ◽  
The Individual ◽  
Individual Grains ◽  
Micro Structures

A survey of recent contributions on three-dimensional grain-scale mechanical modelling of polycrystalline materials is given in this work. The analysis of material micro-structures requires the generation of reliable micro-morphologies and affordable computational meshes as well as the description of the mechanical behavior of the elementary constituents and their interactions. The polycrystalline microstructure is characterized by the topology, morphology and crystallographic orientations of the individual grains and by the grain interfaces and microstructural defects, within the bulk grains and at the inter-granular interfaces. Their analysis has been until recently restricted to two-dimensional cases, due to high computational requirements. In the last decade, however, the wider affordability of increased computational capability has promoted the development of fully three-dimensional models. In this work, different aspects involved in the grain-scale analysis of polycrystalline materials are considered. Different techniques for generating artificial micro-structures, ranging from highly idealized to experimentally based high-fidelity representations, are briefly reviewed. Structured and unstructured meshes are discussed. The main strategies for constitutive modelling of individual bulk grains and inter-granular interfaces are introduced. Some attention has also been devoted to three-dimensional multiscale approaches and some established and emerging applications have been discussed.

Hierarchical Nano/Micro-structured Surfaces with High Surface Area/Volume Ratios

2021 ◽  
pp. 1-36
Author(s):  
Ketki Lichade ◽  
Yizhou Jiang ◽  
Yayue Pan
Keyword(s):  
Surface Structure ◽  
Surface Area ◽  
Light Trapping ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Structure Design ◽  
Surface Structures ◽  
Structured Surfaces ◽  
Design And Manufacture

Abstract Recently, many studies have investigated additive manufacturing of hierarchical surfaces with high surface area/volume (SA/V) ratios, and their performance has been characterized for applications in next-generation functional devices. Despite recent advances, it remains challenging to design and manufacture high SA/V ratio structures with desired functionalities. In this study, we established the complex correlations among the SA/V ratio, surface structure geometry, functionality, and manufacturability in the Two-Photon Polymerization (TPP) process. Inspired by numerous natural structures, we proposed a 3-level hierarchical structure design along with the mathematical modeling of the SA/V ratio. Geometric and manufacturing constraints were modeled to create well-defined three-dimensional hierarchically structured surfaces with a high accuracy. A process flowchart was developed to design the proposed surface structures to achieve the target functionality, SA/V ratio, and geometric accuracy. Surfaces with varied SA/V ratios and hierarchy levels were designed and printed. The wettability and antireflection properties of the fabricated surfaces were characterized. It was observed that the wetting and antireflection properties of the 3-level design could be easily tailored by adjusting the design parameter settings and hierarchy levels. Furthermore, the proposed surface structure could change a naturally-hydrophilic surface to near-superhydrophobic. Geometrical light trapping effects were enabled and the antireflection property could be significantly enhanced (>80% less reflection) by the proposed hierarchical surface structures. Experimental results implied the great potential of the proposed surface structures for various applications such as microfluidics, optics, energy, and interfaces.

scholarly journals A Biomedical Surface Enhanced Raman Scattering Substrate: Functionalized Three-Dimensional Porous Membrane Decorated with Silver Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Li Yuan ◽  
Jinghuai Fang ◽  
Yonglong Jin ◽  
Chaonan Wang ◽  
Tian Xu
Keyword(s):  
Silver Nanoparticles ◽  
Raman Scattering ◽  
Three Dimensional ◽  
Surface Enhanced Raman Scattering ◽  
Porous Membrane ◽  
Raman Signal ◽  
Functional Surface ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

We fabricated a simple, cheap, and functional surface enhanced Raman scattering substrate for biomedical application. Hot spots between two close silver nanoparticles distributed in the skeleton of a three-dimensional porous membrane, especially in the pores, were formed. The dual poles of micropores in the membrane were discussed. The pores could protect the silver nanoparticles in the pores from being oxidized, which makes the membrane effective for a longer period of time. In addition,Staphylococcus aureuscells could be trapped by the micropores and then the Raman signal became stronger, indicating that the functional surface enhanced Raman scattering substrate is reliable.

Investigation of Three-Dimensional Flow in Microchannels With Patterned Surfaces

2007 ◽  
Author(s):  
Auro Ashish Saha ◽  
Sushanta K. Mitra
Keyword(s):  
Surface Tension ◽  
Flow Instability ◽  
Numerical Study ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Bottom Wall ◽  
Surface Tension Effect ◽  
Hydrophobic Region ◽  
Side Walls ◽  
Dimensional Simulation

A three-dimensional numerical simulation of flow in patterned microchannel with alternate layers of hydrophilic and hydrophobic surfaces at the bottom wall is studied here. Surface characteristics of the microchannel are accounted by specifying the contact angle and the surface tension of the fluid. Meniscus profiles with varying amplitude and shapes are obtained under the different specified surface conditions. Flow instability increases as the fluid at the bottom wall traverses alternately from hydrophilic region to hydrophobic region. To understand the surface tension effect of the side walls, a two-dimensional numerical study has also been carried out for the microchannel and the results are compared with three-dimensional simulation. The surface tension effect of the side walls enhances the capillary effect for three-dimensional case.

Bistable Phenomenon of the Aerodynamic Forces on a Square Prism with the Aspect Ratio of 5

2012 ◽  
Vol 256-259 ◽  
pp. 844-849
Author(s):  
Han Feng Wang
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
Side Surface ◽  
Shear Layers ◽  
Cylinder Wake ◽  
Near Wake ◽  
Square Prism ◽  
Bistable Phenomenon ◽  
Side Walls ◽  
Simulation Results

The flow around a finite-length square prism with aspect ratio of 5 is numerical investigated using LES at Red = 3900. The prism is mounted on a flat wall, with one end free. Based on the simulation results, it is found that the near wake is highly three dimensional under the effects of free-end downwash flow. The shear layers from prism side walls and free end form an arch-type structure. There are two typical flow modes presence in the near wake: first, the spanwise vortices are staggered arranged similar to that in 2D cylinder wake; second, the spanwise vortices are quasi-symmetrically arranged. These two modes occur alternately and intermittently. When the first mode occurs, the pressure on the prism side surface fluctuates periodically, corresponding to large values of drag and fluctuating lift coefficients; when the second modes occurs, there is no obvious pressure fluctuation on prism side surfaces, and the correspond drag and fluctuation life coefficients are significantly smaller than those for the first mode.

Micro-Patterning of Silicon by Frictional Interaction and Chemical Reaction

1998 ◽  
Vol 120 (2) ◽  
pp. 353-357 ◽  
Author(s):  
Dae-Eun Kim ◽  
Jae-Joon Yi
Keyword(s):  
Chemical Reaction ◽  
Low Cost ◽  
Three Dimensional ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Micro Electro Mechanical Systems ◽  
Micro Patterning ◽  
Frictional Interaction ◽  
Micro Structures ◽  
Micro Patterns

In this paper a novel and economical method of generating three-dimensional micro-patterns on single crystal silicon without the need for a mask is presented. The technique is based on the fundamental understanding of frictional interaction at light loads. Micro-patterning is done through a two-step process that comprises mechanical scribing and chemical etching. The basic idea is to induce micro-plastic deformation along a prescribed track through frictional interaction between the tool and the workpiece. Then, by exposing the surface to a chemical under controlled conditions, preferential chemical reaction is induced along the track to form hillocks about 5 μm wide and 1 μm high. This method of micro-machining may be used for making patterns in micro-electro-mechanical systems (MEMS) at low cost. Furthermore, this process demonstrates how microtribological processes can be utilized in the fabrication of micro-structures.

The strain hardening behaviour of particulate media

1976 ◽  
Vol 13 (3) ◽  
pp. 311-323 ◽  
Author(s):  
S. Frydman
Keyword(s):  
Strain Hardening ◽  
Three Dimensional ◽  
Flow Rule ◽  
Finite Element Program ◽  
Particulate Media ◽  
Stress Strain Relation ◽  
Element Program ◽  
Plastic Components ◽  
Associated Flow Rule ◽  
Particulate Medium

The strain increment resulting from an increment of stress applied to a particulate medium has been expressed in terms of its elastic and plastic components. The concepts of strain-hardening plasticity have been employed to develop an incremental stress–strain relation, based on a non-associated flow rule. The parameters appearing in the relation have been found using results of three-dimensional shear tests on sands and glass-microspheres. It is suggested that relations of the type developed in the paper could be beneficially incorporated into a finite-element program.

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