scholarly journals Inline measurement strategy for additive manufacturing

2018 ◽  
Vol 233 (5) ◽  
pp. 1402-1411 ◽  
Author(s):  
Matthias Bordron ◽  
Charyar Mehdi-Souzani ◽  
Olivier Bruneau
Keyword(s):  
Additive Manufacturing ◽  
Path Planning ◽  
Free Form ◽  
Elastic Model ◽  
Laser Sensor ◽  
Post Process ◽  
Working Volume ◽  
Inline Measurement ◽  
Cloud Of Points

Additive manufacturing takes a growing place in industry tanks to its ability to create free-form parts with internal complex shape. Yet, the quality of the final surfaces of the additive manufacturing parts is still a challenge since it doesn’t reach the required level for final use. To address this issue, it is necessary to measure the form and dimension deviation in order to plan post-process operations to be considerate. Moreover in a context of industry 4.0, this measurement step should be fully integrated into the manufacturing line as close as possible to the additive manufacturing process and post-process. We introduce in this article an inline measurement solution based on a robot combined with a laser sensor. Robot allows reaching most of the orientation and positions necessary to digitize complex parts in a short time. The use of robot for digitizing is already addressed but not for metrological applications. Robots are perfectly designed for velocity, ability and robustness but their poor positioning accuracy is not compatible with measuring requirements. The strategy adopted in this article is to provide an algorithm to generate path planning for digitizing additive manufacturing parts at a given quality of the resulting cloud of points. After a discussion about the geometric and elastic model of the robot to identify the one that answers the quality requirements, the performances of the robot are evaluated. Thus, several performances maps are introduced to characterize the behavior of the robot in its working volume. The qualification of the digitizing sensor is also performed to identify relation between digitizing parameters and the quality of final cloud of points. Using data resulting from the qualifications of sensor and robot and the parts CAD model, the algorithm allows generating path planning to ensure the final quality necessary to measure the shape deviation.

scholarly journals Early-age creep behaviour of 3D printable mortars: Experimental characterisation and analytical modelling

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Laura Esposito ◽  
Lorenzo Casagrande ◽  
Costantino Menna ◽  
Domenico Asprone ◽  
Ferdinando Auricchio
Keyword(s):  
Additive Manufacturing ◽  
Creep Behaviour ◽  
Digital Fabrication ◽  
Free Form ◽  
Process Time ◽  
Early Age ◽  
Elastic Model ◽  
Layer By Layer ◽  
Fresh State ◽  
Mechanical Properties Prediction

AbstractThe construction sector is experiencing significant technological innovations with digitalisation tools and automated construction techniques, such as additive manufacturing. Additive manufacturing utilising cement-based materials can potentially remove the technological/economic barriers associated with innovative architectural/structural shapes which are not suitable for conventional formworks adopted for concrete material. However, in the “free-form” digital fabrication with concrete, the mechanical properties prediction of the material in the fresh state is essential for controlling both the element deformations and overall stability during printing. In this paper, the authors explore the critical aspects related to the determination of the early-age creep properties of a 3D printable cement-based material, particularly investigating such a behaviour at different resting times. The experimental results are used to calibrate the Burgers’ analytical model to consider both the elastic and the viscous response of the 3D printable mortar investigated in the fresh state. The visco-elastic model is validated by comparing the analytical total strain vs time curve with the corresponding experimental counterpart replicating the layer-by-layer stacking process in the 3D concrete printing process. It was found that the Burgers’ model represents a valuable numerical approach to evaluate the overall accumulation of layer deformation of a 3D printed element, since it is capable of taking into account the time dependency due to the time gap and the variable material stiffness over the process time.

scholarly journals A Review of Post-Processing Technologies in Additive Manufacturing

2021 ◽  
Vol 5 (2) ◽  
pp. 38
Author(s):  
Xing Peng ◽  
Lingbao Kong ◽  
Jerry Ying Hsi Fuh ◽  
Hao Wang
Keyword(s):  
Additive Manufacturing ◽  
Surface Quality ◽  
Complex Geometries ◽  
Operational Flexibility ◽  
Post Processing ◽  
Processing Technologies ◽  
Post Process ◽  
Critical Issues ◽  
Am Processes

Additive manufacturing (AM) technology has rapidly evolved with research advances related to AM processes, materials, and designs. The advantages of AM over conventional techniques include an augmented capability to produce parts with complex geometries, operational flexibility, and reduced production time. However, AM processes also face critical issues, such as poor surface quality and inadequate mechanical properties. Therefore, several post-processing technologies are applied to improve the surface quality of the additively manufactured parts. This work aims to document post-processing technologies and their applications concerning different AM processes. Various types of post-process treatments are reviewed and their integrations with AM process are discussed.

scholarly journals Occlusion Culling for Wide-Angle Computer-Generated Holograms Using Phase Added Stereogram Technique

Photonics ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 298
Author(s):  
Juan Martinez-Carranza ◽  
Tomasz Kozacki ◽  
Rafał Kukołowicz ◽  
Maksymilian Chlipala ◽  
Moncy Sajeev Idicula
Keyword(s):  
Point Sources ◽  
Wide Angle ◽  
Computer Generated Holograms ◽  
Propagation Methods ◽  
Propagation Technique ◽  
3D Scene ◽  
Occlusion Culling ◽  
Fourier Type ◽  
Cloud Of Points

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion between surfaces because it provides correct perception of encoded 3D scenes. Although there is a vast family of occlusion culling algorithms, none of these, at the best of our knowledge, consider occlusion when calculating CGHs with wide-angle view. For that reason, in this work we propose an occlusion culling algorithm for wide-angle CGHs that uses the Fourier-type phase added stereogram (PAS). It is shown that segmentation properties of the PAS can be used for setting efficient conditions for occlusion culling of hidden areas. The method is efficient because it enables processing of dense cloud of points. The investigated case has 24 million of point sources. Moreover, quality of the occluded wide-angle CGHs is tested by two propagation methods. The first propagation technique quantifies quality of point reproduction of calculated CGH, while the second method enables the quality assessment of the occlusion culling operation over an object of complex shape. Finally, the applicability of proposed occlusion PAS algorithm is tested by synthetizing wide-angle CGHs that are numerically and optically reconstructed.

scholarly journals SURFACE ROUGHNESS CONSIDERATIONS IN DESIGN FOR ADDITIVE MANUFACTURING - A LITERATURE REVIEW

2021 ◽  
Vol 1 ◽  
pp. 2841-2850
Author(s):  
Didunoluwa Obilanade ◽  
Christo Dordlofva ◽  
Peter Törlind
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Literature Review ◽  
Future Research ◽  
Reduction Potentials ◽  
Research Fields ◽  
Post Process ◽  
Accessibility Issues ◽  
End Use ◽  
And Performance

AbstractOne often-cited benefit of using metal additive manufacturing (AM) is the possibility to design and produce complex geometries that suit the required function and performance of end-use parts. In this context, laser powder bed fusion (LPBF) is one suitable AM process. Due to accessibility issues and cost-reduction potentials, such ‘complex’ LPBF parts should utilise net-shape manufacturing with minimal use of post-process machining. The inherent surface roughness of LPBF could, however, impede part performance, especially from a structural perspective and in particular regarding fatigue. Engineers must therefore understand the influence of surface roughness on part performance and how to consider it during design. This paper presents a systematic literature review of research related to LPBF surface roughness. In general, research focuses on the relationship between surface roughness and LPBF build parameters, material properties, or post-processing. Research on design support on how to consider surface roughness during design for AM is however scarce. Future research on such supports is therefore important given the effects of surface roughness highlighted in other research fields.

Accuracy Analysis of Fringe Projection Systems Based on Blue Light Technology

2014 ◽  
Vol 615 ◽  
pp. 9-14 ◽  
Author(s):  
Claudio Bernal ◽  
Beatriz de Agustina ◽  
Marta María Marín ◽  
Ana Maria Camacho
Keyword(s):  
Blue Light ◽  
Point Clouds ◽  
Fringe Projection ◽  
Accuracy Analysis ◽  
Scanning Procedure ◽  
Structured Light Scanner ◽  
Cloud Of Points ◽  
3D Digitizing

Some manufacturers of 3D digitizing systems are developing and market more accurate, fastest and affordable systems of fringe projection based on blue light technology. The aim of the present work is the determination of the quality and accuracy of the data provided by the LED structured light scanner Comet L3D (Steinbichler). The quality and accuracy of the cloud of points produced by the scanner is determined by measuring a number of gauge blocks of different sizes. The accuracy range of the scanner has been established through multiple digitizations showing the dependence on different factors such as the characteristics of the object and scanning procedure. Although many factors influence, accuracies announced by manufacturer have been achieved under optimal conditions and it has been noted that the quality of the point clouds (density, noise, dispersion of points) provided by this system is higher than that obtained with laser technology devices.

scholarly journals Automated Testing and Characterization of Additive Manufacturing (ATCAM)

2021 ◽  
Author(s):  
Arash Alex Mazhari ◽  
Randall Ticknor ◽  
Sean Swei ◽  
Stanley Krzesniak ◽  
Mircea Teodorescu
Keyword(s):  
Additive Manufacturing ◽  
Fused Deposition Modeling ◽  
Cell System ◽  
Automated Testing ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Machine Calibration

AbstractThe sensitivity of additive manufacturing (AM) to the variability of feedstock quality, machine calibration, and accuracy drives the need for frequent characterization of fabricated objects for a robust material process. The constant testing is fiscally and logistically intensive, often requiring coupons that are manufactured and tested in independent facilities. As a step toward integrating testing and characterization into the AM process while reducing cost, we propose the automated testing and characterization of AM (ATCAM). ATCAM is configured for fused deposition modeling (FDM) and introduces the concept of dynamic coupons to generate large quantities of basic AM samples. An in situ actuator is printed on the build surface to deploy coupons through impact, which is sensed by a load cell system utilizing machine learning (ML) to correlate AM data. We test ATCAM’s ability to distinguish the quality of three PLA feedstock at differing price points by generating and comparing 3000 dynamic coupons in 10 repetitions of 100 coupon cycles per material. ATCAM correlated the quality of each feedstock and visualized fatigue of in situ actuators over each testing cycle. Three ML algorithms were then compared, with Gradient Boost regression demonstrating a 71% correlation of dynamic coupons to their parent feedstock and provided confidence for the quality of AM data ATCAM generates.

Constrained Shape Scaling of Trimmed NURBS Surfaces

1999 ◽  
Author(s):  
Pifu Zhang ◽  
Caiming Zhang ◽  
Fuhua (Frank) Cheng
Keyword(s):  
Data Exchange ◽  
Surface Deformation ◽  
Current Data ◽  
Free Form ◽  
Test Results ◽  
Nurbs Surface ◽  
Curvature Distribution ◽  
The Given ◽  
Boundary Curves

Abstract A method to scale and deform a trimmed NURBS surface while holding the shape and size of specific features (trimming curves) unchanged is presented. The new surface is formed by scaling the given surface according to the scaling requirement first; and then attaching the (original) features to the scaled NURBS surface at appropriate locations. The attaching process requires several geometric operations and constrained free-form surface deformation. The resulting surface has the same features as the original surface and same boundary curves as the scaled surface while reflecting the shape and curvature distribution of the scaled surface. This is achieved by minimizing a shape-preserving objective function which covers all the factors in the deformation process such as bending, stretching and spring effects. The resulting surface maintains a NURBS representation and, hence, is compatible with most of the current data-exchange standards. Test results on several car parts with trimming curves are included. The, quality of the resulting surfaces is examined using the highlight line model.

Overhanging Feature Analysis for the Additive Manufacturing of Topology Optimized Structures

2018 ◽  
Author(s):  
Dylan Bender ◽  
Ahmad Barari
Keyword(s):  
Additive Manufacturing ◽  
Difference Operator ◽  
Optimized Design ◽  
3D Printer ◽  
Structural Topology ◽  
Gradient Vector ◽  
Distribution Matrix ◽  
Structural Parts ◽  
Part Orientation

This paper presents a methodology to find the optimum build orientation in the additive manufacturing of topologically optimized structural parts. The outlined methodology is based on applying a differential operator to the density distribution matrix of a topologically optimized design. The methodology is developed for 2D parts, where the profile of the geometry is constant. The 2D spatial difference operator effectively calculates the elemental density gradient vector, ultimately used to calculate the angles between i) overhanging surfaces of a topology optimized design, and ii) the build platform of a 3D printer. These angles, referred to as build angles, are used to estimate the relative amount of supporting structure required to print the design at a prescribed part orientation. This methodology can potentially be adopted to simulate the additive manufacturing surface quality of density based, structural topology optimization designs.

scholarly journals The current trend of administering a patient-generated index in the oncological setting: a systematic review

2014 ◽  
Author(s):  
Jessica A. Tang ◽  
Taemin Oh ◽  
Justin K. Scheer ◽  
Andrew T. Parsa
Keyword(s):  
Quality Of Life ◽  
Systematic Review ◽  
Current Trend ◽  
Free Form ◽  
Patient Generated Index ◽  
Novel Approach ◽  
Patient Reported ◽  
Assess Quality ◽  
In The Beginning

The patient-generated index (PGI) is a more novel approach to evaluating health-related quality of life (HRQOL) that allows patients to formulate their own responses in an open-ended format in order to measure HRQOL based on each patient’s own stated goals and expectations. To date the use of PGI in the setting of patients diagnosed with cancer remains relatively less common compared to other health conditions. This systematic review primarily aims to identify current literature in which PGI has been used as a tool to assess quality of life in cancer patients. A systematic review using the MEDLINE database from January 1990 to July 2013 was performed with the following search terms to identify the implementation of PGI in oncology settings: (PGI OR patient generated index OR patient-generated OR patient-reported OR patient generated OR patient reported) AND (cancer OR oncology OR tumor OR neoplasm OR malignancy). Of the 2167 papers initially identified, 10 papers evaluated quality of life in oncology patients by collecting free-form responses from the patient, 4 of which actually used PGI. An overarching theme observed in these studies highlighted the concerns mentioned by patients that were not targeted or detected by standardized quality of life measures. While implementing the PGI may require slightly more investment of resources in the beginning, the potential implications of allowing patients to characterize their quality of life on their own terms are tremendous.

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