Automated Geometric Correction System for Additive Manufacturing Considering Build Orientation

2021 ◽  
pp. 1-30
Author(s):  
Seyedeh Elaheh Ghiasian ◽  
Kemper Lewis
Keyword(s):  
Additive Manufacturing ◽  
Optimization Model ◽  
Experimental Validation ◽  
Minimal Amount ◽  
Feature Size ◽  
Build Orientation ◽  
Computational Performance ◽  
The Difference ◽  
Processing Effort ◽  
Correction System

Abstract One of the current challenges for the additive manufacturing (AM) industry lies in providing component designs compatible with the AM manufacturability and constraints without compromising the component structural functionalities. To address this challenge, we present an automated correction system that provides geometrically feasible designs for additive processes by applying locally effective modifications while avoiding substantial changes in the current designs. Considering a minimum printable feature size from the process parameters, this system identifies the problematic features in an infeasible part's design using a holistic geometric assessment algorithm. Based on the obtained manufacturability feedback, the system then corrects the detected problematic regions using a set of appropriate redesign solutions through an automated procedure. In addition, to reduce the difference between the current and modified part geometries, a novel optimization model for build orientation is presented. Using this model, one can identify appropriate orientations for obtaining a feasible design with a minimal amount of corrections while also reducing the post-processing effort by minimizing the area of contact with the support structure. The functionalities of the presented correction system and the optimization model are illustrated using a number of case studies with varying geometries. The computational performance of the system and an experimental validation are also presented to demonstrate the effectiveness of the implemented detection and modification approaches.

scholarly journals Mode Shape-Based Damage Detection Method (MSDI): Experimental Validation

2021 ◽  
Vol 11 (10) ◽  
pp. 4589
Author(s):  
Ivan Duvnjak ◽  
Domagoj Damjanović ◽  
Marko Bartolac ◽  
Ana Skender
Keyword(s):  
Boundary Conditions ◽  
Damage Detection ◽  
Mode Shape ◽  
Experimental Validation ◽  
Detection Method ◽  
Dynamic Properties ◽  
Damage Index ◽  
Main Principle ◽  
The Difference ◽  
Different Levels

The main principle of vibration-based damage detection in structures is to interpret the changes in dynamic properties of the structure as indicators of damage. In this study, the mode shape damage index (MSDI) method was used to identify discrete damages in plate-like structures. This damage index is based on the difference between modified modal displacements in the undamaged and damaged state of the structure. In order to assess the advantages and limitations of the proposed algorithm, we performed experimental modal analysis on a reinforced concrete (RC) plate under 10 different damage cases. The MSDI values were calculated through considering single and/or multiple damage locations, different levels of damage, and boundary conditions. The experimental results confirmed that the MSDI method can be used to detect the existence of damage, identify single and/or multiple damage locations, and estimate damage severity in the case of single discrete damage.

Recent Developments of the Multiphysics Discrete Element Method for Additive Manufacturing Modeling and Simulation

2017 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Additive Manufacturing ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Additive Manufacture ◽  
Computational Tools ◽  
Computational Performance ◽  
Macro Scale ◽  
Recent Developments ◽  
Am Processes ◽  
Element Method

Recent years have seen a sharp increase in the development and usage of Additive Manufacturing (AM) technologies for a broad range of scientific and industrial purposes. The drastic microstructural differences between materials produced via AM and conventional methods has motivated the development of computational tools that model and simulate AM processes in order to facilitate their control for the purpose of optimizing the desired outcomes. This paper discusses recent advances in the continuing development of the Multiphysics Discrete Element Method (MDEM) for the simulation of AM processes. This particle-based method elegantly encapsulates the relevant physics of powder-based AM processes. In particular, the enrichment of the underlying constitutive behaviors to include thermoplasticity is discussed, as are methodologies for modeling the melting and re-solidification of the feedstock materials. Algorithmic improvements that increase computational performance are also discussed. The MDEM is demonstrated to enable the simulation of the additive manufacture of macro-scale components. Concluding remarks are given on the tasks required for the future development of the MDEM, and the topic of experimental validation is also discussed.

A statistical method for build orientation determination in additive manufacturing

2019 ◽  
Vol 25 (1) ◽  
pp. 187-207 ◽  
Author(s):  
Yicha Zhang ◽  
Ramy Harik ◽  
Georges Fadel ◽  
Alain Bernard
Keyword(s):  
Additive Manufacturing ◽  
Statistical Method ◽  
Supervised Machine Learning ◽  
Surface Model ◽  
Generic Level ◽  
Content Type ◽  
Build Orientation ◽  
Cad Models ◽  
Feature Based ◽  
Orientation Determination

Purpose For part models with complex shape features or freeform shapes, the existing build orientation determination methods may have issues, such as difficulty in defining features and costly computation. To deal with these issues, this paper aims to introduce a new statistical method to develop fast automatic decision support tools for additive manufacturing build orientation determination. Design/methodology/approach The proposed method applies a non-supervised machine learning method, K-Means Clustering with Davies–Bouldin Criterion cluster measuring, to rapidly decompose a surface model into facet clusters and efficiently generate a set of meaningful alternative build orientations. To evaluate alternative build orientations at a generic level, a statistical approach is defined. Findings A group of illustrative examples and comparative case studies are presented in the paper for method validation. The proposed method can help production engineers solve decision problems related to identifying an optimal build orientation for complex and freeform CAD models, especially models from the medical and aerospace application domains with much efficiency. Originality/value The proposed method avoids the limitations of traditional feature-based methods and pure computation-based methods. It provides engineers a new efficient decision-making tool to rapidly determine the optimal build orientation for complex and freeform CAD models.

Multi-Component Topology Optimization for Powder Bed Additive Manufacturing (MTO-A)

2018 ◽  
Author(s):  
Yuqing Zhou ◽  
Tsuyoshi Nomura ◽  
Kazuhiro Saitou
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Simultaneous Optimization ◽  
Previous Attempt ◽  
Numerical Instability ◽  
Feature Size ◽  
Powder Bed ◽  
Nonlinear Projection ◽  
Gradient Based ◽  
Length Width

This paper presents a gradient-based multi-component topology optimization (MTO) method for structures assembled from components made by powder bed additive manufacturing. It is built upon our previous work on the continuously-relaxed MTO framework utilizing the concept of fractional component membership. The previous attempt on the integration of the relaxed MTO framework with additive manufacturing constraints, however, suffered from numerical instability for larger size problems, limiting its application to 2D low-resolution examples. To overcome this difficulty, this paper proposes an improved MTO formulation based on a design field regularization and a nonlinear projection of component membership variables, with a focus on powder bed additive manufacturing. For each component, constraints on the maximum allowable build volume (i.e., length, width, and height), the elimination of enclosed voids, and the minimum printable feature size are imposed during the simultaneous optimization of the overall base topology and component partitioning. The scalability of the new MTO formulation is demonstrated by a few 2D examples with much higher resolution than previously reported, and the first reported 3D example of MTO.

Shape-driven control of layer height in robotic wire and arc additive manufacturing

2019 ◽  
Vol 25 (10) ◽  
pp. 1637-1646 ◽  
Author(s):  
Bohao Xu ◽  
Xiaodong Tan ◽  
Xizhi Gu ◽  
Donghong Ding ◽  
Yuelin Deng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Deposition Rate ◽  
Control Method ◽  
Single Layer ◽  
Optimization Method ◽  
Content Type ◽  
Layer Height ◽  
Layer Deposition ◽  
Complex Shapes ◽  
The Difference

Purpose Once an uneven substrate is aligned, traditional control theories and methods can be used on it, so aligning is of great significance for the development of wire and arc additive manufacturing (WAAM). This paper aims to propose a shape-driven control method for aligning a substrate with slopes to expand the application of WAAM. Design/methodology/approach A substrate with slopes must be aligned by depositing weld beads with slopes. First, considering the large height differences of slopes, multi-layer deposition is needed, and the number of layer of weld beads must be ascertained. Second, the change in the deposition rate is controlled as a ramp function to generate weld beads with slopes. Third, the variation of the deposition rate must be fine-tuned to compensate for the deviation between the actual and theoretical layer heights at the deposition of each layer. Finally, the parameters of the ramp functions at the deposition of each layer are determined through an optimization method. Findings First, to model the response function of layer height to deposition rate, the experiments are conducted with the deposition rate jumping from 4 to 8 mm/s and from 8 to 4 mm/s. When the deposition rate jumps from 4 to 8 mm/s and from 8 to 4 mm/s, the difference in the height of each layer decreases as the number of layer increases. Second, the variation of the deposition rate can be fine-tuned based on the deviation between the measured and theoretical layer heights because the variation of the deposition rate is proportional to the layer height when the initial and end deposition rates are near 4 or 8 mm/s, respectively. Third, the experimental results demonstrate that the proposed method is effective for single-layer aligning and aligning a substrate with one or more slopes. Originality/value The proposed method can expand the application of WAAM to an uneven substrate with slopes and lays the foundation for aligning tasks focused on uneven substrates with more complex shapes.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

scholarly journals Road lighting density and brightness linked with increased cycling rates after-dark

2020 ◽  
Author(s):  
Jim Uttley ◽  
Steve Fotios ◽  
Robin Lovelace
Keyword(s):  
Negative Impact ◽  
Time Of Day ◽  
Aerial Images ◽  
Minimal Amount ◽  
Night Time ◽  
Road Lighting ◽  
International Policies ◽  
Relative Brightness ◽  
Two Measures ◽  
The Difference

Cycling has a range of benefits as is recognised by national and international policies aiming to increase cycling rates. Darkness acts as a barrier to people cycling, with fewer people cycling after-dark when seasonal and time-of-day factors are accounted for. This paper explores whether road lighting can reduce the negative impact of darkness on cycling rates. Changes in cycling rates between daylight and after-dark were quantified for 48 locations in Birmingham, United Kingdom, by calculating an odds ratio. These odds ratios were compared against two measures of road lighting at each location: 1) Density of road lighting lanterns; 2) Relative brightness as estimated from night-time aerial images. Locations with no road lighting showed a significantly greater reduction in cycling after-dark compared with locations that had some lighting. A nonlinear relationship was found between relative brightness at a location at night and the reduction in cyclists after-dark. Small initial increases in brightness resulted in large reductions in the difference between cyclist numbers in daylight and after-dark, but this effect reached a plateau as brightness increased. These results suggest only a minimal amount of lighting may be sufficient to promote cycling after-dark.

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