Are Strandlie

Material jetting (MJT) is a promising additive manufacturing (AM) technique that offers high-quality appearance reproduction. Considering the limited selection of aesthetic materials available for MJT technology, a thorough optical analysis is required to determine their optimal application. This study focuses on the prominent appearance attributes in MJT and the role of texture variation due to different build orientations (BOs). For this purpose, tilted surfaces were manufactured in a direction ranging from 0° to 90° degrees at 15° intervals. The spectral reflectance, absorbance, transmittance, color difference, gloss, haze, scattering, and texture of MJT objects with varying BOs were investigated. To illustrate the variation in visual appearance and texture of the studied surfaces, the optical properties were rendered to three-dimensional (3D) spherical models. Further, the interaction of the appearance of 3D printing …

The study conducts an experimental investigation to compare the effect of accelerated aging on a glass fiber/vinylester matrix filament wound composite. Two static aging conditions, thermal and hygrothermal, were chosen. Samples were aged at temperatures below the glass transition temperature (Tg) of vinylester for 224 days. Mechanical test – ILSS and flexure testing and physicochemical assessments – DMA, FTIR and colorimetry were conducted to gauge the aging effects on long-term durability and appearance. Results are presented as retained property values over aging durations and environments. Notably, coupons aged below 60 °C under both conditions exhibited residual curing, enhancing mechanical properties. Time-temperature coupling influenced behavior, with higher temperatures and longer durations leading to degradation. Hygrothermal aging at 80 °C prompted earlier degradation than …

Filament winding is a technique to manufacture tubular composite structures and, therefore, is among the most appealing techniques for fabricating critical structures such as hollow tubes. Despite the recent advances, these structures are prone to a varying degree of porosity that may affect their mechanical performance. Therefore, the accurate detection and quantification of the manufacturing porosity is crucial. Micro-CT is most suitable for performing this activity at various scales. This work employs micro-CT for studying porosity inside an as-manufactured filament-winded composite structure. Void characteristics like volume, orientation, size, and relative volume fraction inside the hoop and helical layers are quantified inside a representative curved panel extracted from a glass fiber-vinyl ester tubular composite structure, which has not been studied in detail previously. It was observed that most voids are present in …

As a result of the associated costs and environmental impacts, Material Jetting (MJT) plays a limited role in Additive Manufacturing (AM). Research on the durability and long-term performance of MJT objects by evaluating their appearance is lacking. The objective of this study is to investigate the effect of aging on the color and the physico-mechanical performance of MJT parts. This work examines the influence of production settings on objects subjected to a total of 103days of accelerated aging. The studied Printing Primary Parameters (PPPs) were resin color, build platform position (swath), and finishing configurations. The results indicated the response of the studied PPP according to the aging time was non-linear due to the dynamic appearance response to aging time. VeroBlackPlus and VeroCyan photo resins demonstrated superior color fidelity through aging by a color difference of less than 10. Based on …

Material jetting (MJT) is a recognized additive manufacturing (AM) method to combine various materials and create a wide range of designed appearances. However, the measured color of MJT objects is frequently different from the color provided in the printer software. As a result, estimating the color quality and the measured color attributes of an object before printing is vital for accurate color reproduction. This study investigates the color variation based on the texture in an object 3D-printed using the MJT method on a rotary tray. The novel radial shape of the rotary tray build platform and variation in the layers structure were targeted as the main factors that can increase the uncertainty in accurate color reproduction. The influence of the PolyJet printer setup has been examined by thickness variation of the colored layers, location on the tray (swath selection), ink color, and finish type between layers. Color quality …

Additively manufactured (AM) parts still lack a thorough understanding of their optical properties, particularly surface texture and reflectance characteristics at different viewing angles. This study examines the reflectance properties of material jetting (MJT) parts using bidirectional reflectance distribution functions (BRDFs). The visual appearance of the MJT parts was analyzed using a gonio-spectrophotometer at 328 unique incidence and viewing geometries for seven different wedge angles for build orientation (BO) from 0° to 90° at 15° intervals. The redundancy analysis (RDA) and principal component analysis (PCA) were used to study BO and to determine the prominent measurement geometries. The results indicate higher BOs resulted in more color and texture variation and rougher surfaces, with Sq 4.21 μm vertical compared to 1.42 μm for horizontal BOs. Furthermore, it affected the visual representation and …

Material jetting (MJT) products have a high subjective appearance quality in additive manufacturing (AM). MJT objects are typically manufactured from multiple layers of semi-transparent photo resins to achieve the desired appearance. This study explores the optical properties of photopolymer plates in monolayer and bilayer combinations. The role of the white substrate as the background plate in bilayer configurations is discussed concerning appearance reproduction in MJT parts. For this purpose, spectral reflectance, transmittance, absorbance, color difference, and texture were investigated for MJT objects with different plate combinations. The primary digital materials in MJT were further investigated for haze, gloss, scattering variations, and their corresponding bidirectional reflectance distribution functions (BRDFs). The optical properties of the studied surfaces were then applied to three-dimensional (3D …

Multi-material fused filament fabrication (FFF) offers the ability to print 3D objects with very diverse surface appearances. However, control of the surface appearance is largely a matter of trial and error unless the employed materials are very similar and very translucent, so we can think of them as blending together. When the multiple materials are fused into one filament in a diamond hotend extruder but do not blend, the resulting surface appearance depends on the printing direction. We explore how this leads to milli-scale colorations as a function of the printing direction. By having preferable printing directions, it is possible to exploit the limited color blending of this nozzle with multiple inlets and one outlet and further enhance particular color effects, such as goniochromatism. We present a framework based on both experimental and computational fluid dynamics analysis for controlling the extrusion process and …

Surface roughness is gaining increasing recognition in the processing design methods of additive manufacturing (AM) due to its role in many critical applications. This impact extends not only to various AM product manufacturing but also to indirect applications, such as molding and casting. This review article discusses the role of processing on the surface roughness of AM-printed polymers with limited post-processing by summarizing recent advances. This review offers a benchmark for surface quality improvement of AM processes, considering the surface roughness of polymeric parts. For this purpose, it lists and analyzes the key processes and various printing parameters used to monitor and adjust surface roughness under given constraints. Four AM techniques for manufacturing polymeric parts are compared: fused filament fabrication (FFF), selective laser sintering (SLS), vat photopolymerization (VPP), and …

One correction is noted for the paper. The branching fraction was not included in the conversion of the observed cross-section limit, pb to the coupling constants and and the branching fractions and. The inclusion leads to weaker observed exclusion limits on the coupling constants divided by the scale of new physics of and and on the branching fractions and. The predicted exclusion limits on the coupling constants divided by the scale of new physics are and and on the branching fractions and. Updated distributions of the observed upper limits on the coupling constants for combinations of cgt and ugt channels are shown in Figure 10 a and on the branching fractions in Figure 10 b.

A precise measurement of the integrated luminosity is a key component of the ATLAS physics programme at the CERN Large Hadron Collider (LHC), in particular for cross-section measurements where it is often one of the leading sources of uncertainty. Searches for new physics phenomena beyond those predicted by the Standard Model also often require accurate estimates of the luminosity to determine background levels and sensitivity. This paper describes the measurement of the luminosity of the proton–proton (????????) collision data sample delivered to the ATLAS detector at a centre-of-mass energy of

Predicting the long-term response of polymer composite materials is a continuous challenge to the composite industry. The service aging of structural composites has different effects on composites’ physicochemical behavior manifested as changes in the mechanical properties. This work presents the effects of hot/wet and hot/dry accelerated aging conditions on the interlaminar shear properties of vinyl-ester glass fiber coupons made with filament winding. The test coupons were aged for 224 days, removed and tested after every 28, 56, 112, and 224 days. It was observed that the response of composite coupons is different for the hot/wet and hot/dry aging environments for same duration of aging. This is attributed to the time-temperature-environment coupling during the aging regime. The overall response of the composite behavior is then represented via retention curves and degradation maps that can help correlate the results for both hot/wet and hot/dry aging environment as a function of exposure times and temperatures. The findings of the study thus provide an insight on the dependence of matrix-dominated properties of composite. The results can be taken into account when designing structure made from vinyl-ester glass fiber filament winded composite which foresee aging in hot/wet and hot/dry conditions.

This study examines the impact of additive manufacturing (AM) settings on the durability of 3D-printed polymer composite objects in terms of object color appearance and corresponding mechanical properties when subjected to simulated environmental conditions using accelerated aging. For this purpose, the AM pre-processing factors that influence the performance of the composite material, such as build platform position, color, and finishing configurations, are discussed. The experimental campaign was designed according to the Taguchi method to minimize the color difference and maximize the mechanical parameters. The results indicate that the best factor parameters for each performance characteristic differ following the design goal. Accordingly, black-on-white with a glossy-on-matte finish manufactured on the outer swath demonstrated the best color and mechanical performance fidelity, where the studied properties were not altered significantly due to aging.

The book describes methods of track and vertex resonstruction in particle detectors. The main topics are pattern recognition and statistical estimation of geometrical and physical properties of charged particles and of interaction and decay vertices.

Track fitting is an application of established statistical estimation procedures with well-known properties. For a long time, estimators based on the least-squares principle were—with some notable exceptions—the principal methods for track fitting. More recently, robust and adaptive methods have found their way into the reconstruction programs. The first section of the chapter presents least-squares regression, the extended Kalman filter, regression with breakpoints, general broken lines and the triplet fit. The following section discusses robust regression by the M-estimator, the deterministic annealing filter, and the Gaussian-sum filter for electron reconstruction. The next section deals with linearized fits of space points to circles and helices. The chapter concludes with a section on track quality and shows how to test the track hypothesis, how to detect outliers, and how to find kinks in a track.

Vertex finding is the search for clusters of tracks that originate at the same point in space. The chapter discusses a variety of methods for finding primary vertices, first in one and then in three dimensions. Details are given on model-based clustering, the EM algorithm and clustering by deterministic annealing in 1D, and greedy clustering, iterated estimators, topological vertex finding, and a vertex finder based on medical imaging in 3D.

The chapter gives an overview of particle detectors, with the emphasis on tracking detectors. The working principles and the calibration of gaseous, semiconductor, and fiber detectors are explained, followed by a brief review of detector alignment. As an illustration, the tracking systems of the four experiments at the LHC and two non-LHC experiments, Belle II and CBM, are presented.

A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider corresponding to an integrated luminosity of 139 fb− 1 is presented. Events are selected if they contain a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The events are categorised according to the number of jets and how likely these are to contain b-hadrons. A multivariate technique is then used to discriminate between signal and background events. The measured four-top-quark production cross section is found to be fb, with a corresponding observed (expected) significance of 1.9 (1.0) standard deviations over the background-only hypothesis. The result is combined with the previous measurement performed by the ATLAS Collaboration in the multilepton final state. The combined four …

The chapter gives an overview of the track and vertex reconstruction methods of the LHC experiments that were used in production during Run 2 of the LHC, which ended in autumn of 2018.

There is no systematic theory of track finding yet. Therefore, the first section of this chapter presents a list of basic techniques which have been successfully used, stand-alone or in combination, in past and present experiments. Among them are the conformal transformation, the Hough and the Legendre transform, cellular automata and neural networks, pattern matching, and track following by the combinatorial Kalman filter. The following section gives a brief excursion into online or real-time track finding in the collider experiments CDF, ATLAS, and CMS. As track finding in most cases delivers some candidates that do not correspond to actual particle tracks, the concluding section discusses methods for an efficient selection of valid candidates.