Multi Objective Optimisation of Build Orientation for Rapid Prototyping with Fused Deposition Modeling (FDM)

The ability to select the optimal orientation of build up is one of the critical factors since it affects the part surface quality, accuracy, build time and part cost. Various factors to be considered in optimisation of build orientation for FDM are build material, support material, build up time, surface roughness and total cost. Experiments were carried out and results are analysed for varying build orientation for primitive geometries like cylinder. An appropriate weighting factor has been considered for various objective functions depending on the specific requirement of the part while carrying out multi-objective optimisation. These analyses will help process engineers to decide proper build orientation.Mechanical Engineerin

Resource Based Build Direction in Additive Manufacturing Process

Three dimensional free-form geometric shapes can be built by putting layers upon layer in a predefined direction via Additive Manufacturing (AM) processes. The fabrication processes require computational as well as physical resources and can vary not only upon the product but its process plan. Overly simplified process plan may expedite the pre-fabrication techniques, but may create difficulty during fabrication of those slices. For an example, slices with concavity or discrete contour plurality may introduce deposition discontinuity, over deposition, and higher build time during the fabrication. These issues demand more resources there by affecting the part quality and fabrication cost. In this work, we focus upon the build direction of AM process plan to address the fabrication and resource utilization. First, a set of uniform build direction is identified and the object is discretized using a set of critical points considering the object concavity along the build direction. Cutting planes are generated and the object is discretized into strips and each strip is analyzed for contour plurality and the build directions are quantified through the allocation of importance factors. The optimal build direction thus found will result in lowest possible fabrication complexity. The proposed methodology is implemented and presented with a sample example in this paper.Mechanical Engineerin

Рациональная ориентация изделия при его послойном формообразовании на основе статистического анализа исходной триангуляционной 3D модели

Рассмотрена возможность рациональной ориентации изделия при послойном построении на основе статистического анализа распределения углов, образованные между векторами нормалей граней триангуляционной модели и направлением построения. Предложен подход, позволяющий обоснованно определять углы поворота исходной триангуляционной модели для эффективной материализации аддитивными технологиями. Приведены примеры применения предлагаемого подхода при послойном построении изделий аддитивными технологиями.The possibility of rational orientation of product in layer-by-layer build on the basis of statistical analysis of the distribution of angles formed between normal vector of faces of triangulation model and the build direction. The proposed approach, allowing to determine the rotation angles of the original triangulated model for effective materialization of additive technologies. Examples of application of proposed approach for layered construction of products of additive technologies

A Visual Tool to Improve Layered Manufacturing Part Quality

A software tool is described that will aid the user in. choosing the optimum build orientation to obtain the ..best composite set of surface finishes on a part built .on a Fused Deposition Modeling (FDM) rapid prototyping machine.• Experiments were conducted to obtain statistical .surface roughness values as a function of orientation and layer thickness.Three types of surfaces (features}.have been. considered planar (both upward facing and downward facing (over hang surfaces)),.quadratic and free form Surfaces..Data analysis of surface roughness of planar surfaces at various orientations·and their mapping. to. quadratic and freeform surfaces are presented. decision support software tool allows dynamic .. color-coded visualization of the surface quality simultaneous with build parameters including orientation and layer thickness.Mechanical Engineerin

Оценка исходной 3D-модели на приспособленность к определению рациональной ориентации изделия при послойном построении

Рассмотрена возможность оценки технологичности конструкции изделия на основе статистического анализа распределения площади граней при сферическом отображении исходной триангуляционной модели. Предложен показатель, позволяющий при отработке конструкции на технологичность количественно оценивать возможность определения рациональной ориентации изделия в рабочем пространстве установки послойного построения.The possibility of evaluating workability of industrial product on the basis of a statistical analysis of the distribution of the area of faces obtained by spherical mapping of original triangulation model is considered. An index is proposed that allows to assess the possibility of determining the rational orientation of a product in the working space of a layer-by-layer installation when the design is tested for the workability

Оценка исходной 3D-модели на приспособленность к определению рациональной ориентации изделия при послойном построении

Рассмотрена возможность оценки технологичности конструкции изделия на основе статистического анализа распределения площади граней при сферическом отображении исходной триангуляционной модели. Предложен показатель, позволяющий при отработке конструкции на технологичность количественно оценивать возможность определения рациональной ориентации изделия в рабочем пространстве установки послойного построения.The possibility of evaluating workability of industrial product on the basis of a statistical analysis of the distribution of the area of faces obtained by spherical mapping of original triangulation model is considered. An index is proposed that allows to assess the possibility of determining the rational orientation of a product in the working space of a layer-by-layer installation when the design is tested for the workability

Layerless fabrication with continuous liquid interface production

Despite the increasing popularity of 3D printing, also known as additive manufacturing (AM), the technique has not developed beyond the realm of rapid prototyping. This confinement of the field can be attributed to the inherent flaws of layer-by-layer printing and, in particular, anisotropic mechanical properties that depend on print direction, visible by the staircasing surface finish effect. Continuous liquid interface production (CLIP) is an alternative approach to AM that capitalizes on the fundamental principle of oxygen-inhibited photopolymerization to generate a continual liquid interface of uncured resin between the growing part and the exposure window. This interface eliminates the necessity of an iterative layer-by-layer process, allowing for continuous production. Herein we report the advantages of continuous production, specifically the fabrication of layerless parts. These advantages enable the fabrication of large overhangs without the use of supports, reduction of the staircasing effect without compromising fabrication time, and isotropic mechanical properties. Combined, these advantages result in multiple indicators of layerless and monolithic fabrication using CLIP technology

Feasibility of Additive Manufactured Materials for Use in Geotechnical Laboratory Testing Applications

The factors affecting the positive volumetric strain, or dilatancy, typically observed in response to shearing of a dense granular material have long been investigated; however, there still lacks a direct relationship between particle shapes and the resulting dilatant response. The typical Mohr-Coulomb strength parameter associated with granular material is known as the effective friction angle (φ’). For a dense granular assemblage, the peak friction angle has been described as being comprised of a dilatant friction angle (φ’d) component and a critical state friction angle (φ’cv) component. While the topic of dilatancy and factors (both inherent and extrinsic) affecting its behavior are understood by researchers, added complexity exists due to the dependency of the dilatation angle on features such as density, confining stress, and stress path. With continuous innovation in additive manufacturing (AM), the technology has encompassed a broader spectrum of users including scientists and engineers. AM provides a new avenue for understanding the effect of particle shape on the dilatant response of granular material by providing the ability to change shape geometry while maintaining consistent material properties. It is hypothesized that an AM-fabricated analogue soil sample can then be used in a laboratory setting. A preliminary investigation was carried out to identify the various AM technologies available and their associated materials. After examining the strength and stiffness characteristics of the various materials, two separate AM technologies were selected. An analogue soil sample was fabricated using each device and was tested in consolidated drained triaxial compression. The analogue soils provided a shearing behavior similar to that of natural granular materials, thus indicating its feasibility for additional studies in geotechnical engineering

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044