Mechanical Properties Of Parts Research Articles

Two-staged attention-based identification of the porosity with the composite features of spatters during the laser powder bed fusion

Porosity is one of the most serious defects in laser powder bed fusion (LPBF). Reducing porosity is essential to improve the mechanical properties of parts in high-end applications. It is found that the spatter dynamic status is closely related to the porosity, giving an idea to identify. In this study, we propose a novel approach for in-situ identification of porosity in the LPBF with spatter features. To achieve efficient and accurate detection, segmentation, and motion tracking of spatters from captured high-speed images during the LPBF process, YOLO and DeepSORT algorithms are employed. Subsequently, a two-staged attention-based recurrent neural network (TARNN) method is proposed to realize the classification of porosity. The input to TARNN consists of both static and dynamic spatter features extracted from every 10 consecutive frames. Leveraging the RNN architecture enables us to effectively exploit temporal information. Moreover, we introduce an attention-aware linear layer and an attention-based RNN to enhance the extraction of representative features related to porosity characteristics. Through the analysis of the attention mechanism, we can explicitly assess the importance ranking of input features, providing a deeper understanding of spatter features. Experimental results demonstrate the superior performance of the proposed TARNN, with an accuracy of 99.50 % at an inference time of 6.5 milliseconds. The proposed method offers a promising avenue for advancing the understanding and characterization of porosity using spatter features in the LPBF process.

Application of Linear Mixed-Effects Model, Principal Component Analysis, and Clustering to Direct Energy Deposition Fabricated Parts Using FEM Simulation Data.

The purpose of this study is to investigate the effects of toolpath patterns, geometry types, and layering effects on the mechanical properties of parts manufactured by direct energy deposition (DED) additive manufacturing using data analysis and machine learning methods. A total of twelve case studies were conducted, involving four distinct geometries, each paired with three different toolpath patterns based on finite element method (FEM) simulations. These simulations focused on residual stresses, strains, and maximum principal stresses at various nodes. A comprehensive analysis was performed using a linear mixed-effects (LME) model, principal component analysis (PCA), and self-organizing map (SOM) clustering. The LME model quantified the contributions of geometry, toolpath, and layer number to mechanical properties, while PCA identified key variables with high variance. SOM clustering was used to classify the data, revealing patterns related to stress and strain distributions across different geometries and toolpaths. In conclusion, LME, PCA, and SOM offer valuable insights into the final mechanical properties of DED-fabricated parts.

Molecular dynamics research on the effect of selective laser melting parameters on porosity and properties of parts

Selective laser melting (SLM) is considered as a new production technology which has the potential to produce amorphous alloy parts. However, pores are often observed in parts prepared by SLM, which seriously affect the properties and life of the parts. In this work, an atomic model for SLM forming of Cu50Zr50 amorphous alloy is established. The effects of laser power and scanning speed on the porosity and mechanical properties of parts fabricate by SLM are researched using molecular dynamics methods. The results indicate that increasing laser power or reducing laser scanning speed could enhance the laser energy input of the molten pool and increase the molten pool temperature, which could improve the fluidity of the metal melt and prolong the existence time of the molten pool. The molten metal could fully fill the gaps between powders, which reduces the porosity and is beneficial to obtain dense parts. The tensile strength of samples formed by SLM is positively correlated with their porosity. Stress concentration occurs in the system with through holes and internal pores. Defects expand and interconnect rapidly under stress concentration, which leads to a decrease in strength and plasticity. The porosity could be reduced by adjusting the process parameters, thus improving the mechanical properties of the parts. This study provides a theoretical reference for a deeper understanding of the formation mechanism of SLM pores and the development of advanced alloys with high density.

Optimisation of microstructures from filament extrusion additive manufacturing based on numerical simulation with VOLCO-X

The mechanical properties of parts built with material extrusion additive manufacturing are highly dependent on the material distribution within parts’ microstructure. This varies with the choice of process parameters. Therefore, when designing a functional printed part, one must tailor the printing parameters in order to obtain the desired properties, such as minimal voids. The present work proposes an optimisation method that designs printing parameters to minimise manufacturing time while keeping the void volume fraction at very low values (hence improving mechanical properties), keeping dimensions within tight tolerances and guaranteeing structural integrity. The new optimisation method utilises the authors’ previously developed software VOLCO-X, which is capable of efficiently predicting material distribution from filament extrusion within printed parts, including print track dimensions and microstructure geometry, without the need for any experimental calibration. In order to validate the proposed optimisation scheme, optimised printed parts using the scheme and parts using printing parameters determined by a commercial slicing software were manufactured and compared for different printing speeds and deposition strategies. At printing speed of 16 mm/s, it was possible to decrease the manufacturing time by more than 20% and structural mass by more than 5% in comparison to the commercial slicer printed part, whilst maintaining similar mechanical properties. At printing speed of 96 mm/s, due to the high printing speed, the commercial printed part presented gap faults between deposited strands, while the optimised part had structural integrity. At this printing speed, the optimised printed part presented significant improvements in terms of mechanical properties. The proposed optimisation methodology, in conjunction with VOLCO-X, is a powerful tool that can be used to improve manufacturing by filament extrusion. This innovative tool allows the identification of printing parameters without experiments and trial-and-error approaches, thus saving time and expense.

Response of PLA material to 3D printing speeds: A comprehensive examination on mechanical properties and production quality

This study investigates the impact of printing speed on the mechanical properties of parts produced through the fused deposition modeling (FDM) method using a three-dimensional (3D) printer. Tensile test specimens, fabricated with Polylactic Acid (PLA) material on an Ender 3 S1 3D printer, were subjected to varying printing speeds from 15 mm/s to 105 mm/s in 15 mm/s increments, maintaining a 100% infill rate. Detailed measurements of sample masses, hardness values, and surface roughness were conducted to assess the potential effects of printing speed on PLA’s mechanical properties. Porosity values were also calculated to evaluate internal structure homogeneity and void ratios. The results indicate that an increase in printing speed leads to a substantial reduction in production time. For instance, at a speed of 15 mm/s, the printing time was 119 minutes, decreasing to 15 minutes at 105 mm/s. As speed increased, there was a tendency for a decrease in sample masses, with a notable 12% reduction from 8.21 grams at 15 mm/s to 7.21 grams at 105 mm/s. While lower speeds (15 and 30 mm/s) exhibited higher Shore D hardness values, an overall decrease in hardness was observed with increasing speed. Surface roughness showed a proportional increase with printing speed; for example, at 0° angle, the roughness value increased from 0.8 at 15 mm/s to 1.9 at 105 mm/s. Moreover, tensile strength values decreased with higher printing speeds. For samples printed at 15 mm/s, the tensile strength was 60 MPa, decreasing to 44 MPa at 105 mm/s, representing a 27% reduction. These numerical findings underscore the significant influence of 3D printing speed on both production efficiency and the mechanical properties of the printed material.

Determination of selective laser melting process parameters of tungsten carbide powders coated with nickel via electroless plating for improved interface properties

Tungsten carbide powders are commonly used at various industrial applications due to their high hardness. However, these powders may exhibit low binding and processing challenges without a binder. Therefore, various binding methods such as electroless Ni coating are used to hold WC powders together, increase their processability and improve the mechanical properties of the final product. Electroless Ni plating plays an important role in the use of WC powders, especially in processes such as selective laser melting. The structural, tribological, and mechanical properties of parts manufactured by SLM method are significantly influenced by the parameters employed in the process. Hence, optimizing process variables is essential to unlock the full potential of this advanced manufacturing technique. The main objective of this study was to identify the optimum process parameters for the SLM method of WC-Ni composite powders, which were prepared by coating WC powder materials with electroless Ni. Experimental investigations focused on analyzing the laser power, scanning speed, and hatch spacing parameters. The effects of these parameters on the mechanical and tribological properties of WC-Ni composite material were investigated using microhardness tester, tribometer device, optical microscope, 3D optical profilometer and scanning electron microscope. Eventually, it was determined that the manufacturing parameters employed in the SLM method had a significant impact on relative density, microstructure, surface roughness, hardness, and tribological properties. Samples exhibited a relative density of nearly 99%, and the highest observed hardness value was 1962 HV. This article supports a specialized SLM manufacturing process developed specifically to enhance durability and performance across a broad spectrum of industrial applications through interface improvement and the optimization of manufacturing parameters.

Microstructure evolution and strengthening mechanism of pure copper sheet induced by laser shock forming

laser shock forming (LSF) is a high strain rate forming process, which can significantly improve the formability of materials. Nevertheless, there is a lack of research on the microstructure evolution and improving mechanical properties of parts deformed by LSF. In this paper, pure copper sheet are formed into flat bottom parts under one- and two-shot LSF. The deformation topography, surface morphology and thickness distribution of the deformed parts are tested. The surface micro morphology of the mould can be additionally printed in the formed parts, and the sheet forming accuracy improved continuously and lower thickness thinning with the increase of the shock number. Transmission electron microscopy (TEM) showed that the microstructure on the surface of the formed specimens was composed of nanocrystalline arrays elongated in the direction of the transverse flow of the workpiece material. The dislocation density decreased and the twinned structures gradually disappeared with an increasing depth from the treated surface. More laser shocking can refine the metal material grain and improve material mechanical property of the formed part further. Eventually, the underlying improvement mechanism of mechanical properties induced by LSF-induced microstructure evolution on pure copper was systematically revealed.

Mechanical performances of continuous carbon fiber reinforced PEEK (polyether ether ketone) composites printed in a vacuum environment

Continuous fiber-reinforced thermoplastic (CFRTP) composites have attracted significant attention in various industries due to their exceptional mechanical properties and lightweight nature. Various methods have been applied to improve the mechanical properties of parts produced by fused deposition modeling (FDM), such as printing in a vacuum environment. Vacuum is utilized during printing to minimize heat transfer by convection, improve interfacial bonding, and reduce void formation. This study investigates the effects of vacuum and process parameters on the mechanical and microstructural properties of continuous fiber-reinforced thermoplastic composites. The goal was to investigate the effects of the printing parameters in a vacuum environment and therefore, enhance the mechanical properties. CFRTP test specimens were produced under various vacuum levels and processed at nozzle temperatures, heated bed temperatures, and printing speeds. Three-point bending tests were conducted to evaluate the flexural properties, and microstructural analysis was performed using optical microscopy. The results demonstrate the positive influence of vacuum on flexural performance and highlight the importance of controlling parameters, such as nozzle temperature and heated bed temperature for achieving enhanced mechanical properties. This study provides valuable insights into the production of higher mechanical properties of CFRTP composites and contributes to advancements in their manufacturing.

The process‐structure–property relationship of 3D printed G‐Polymer using fused filament fabrication technique

AbstractThe ever‐increasing demand for additive manufacturing (AM) is driven by the technology's rapid prototyping and flexible manufacturing benefits. Among the various AM techniques, fused filament fabrication (FFF) is one of the most commonly used techniques, in which thermoplastic polymer filaments are deposited layer by layer to create the final part. This technique has been used extensively in various sectors. However, new materials have yet to be developed for use in FFF. This research aims to introduce a new biodegradable highly amorphous polyvinyl alcohol (HAVOH), commercially known as G‐Polymer (GP), into the scope of FFF, to propose a process window for the fabrication of parts with enhanced mechanical properties and to discover the process‐structure–property relationship for this material. This study investigates the effect of five key parameters in GP FFF, including raster angle, number of contours, nozzle temperature, build platform temperature, and print speed. The results of the chemical, thermal, and thermo‐mechanical analysis of the filaments before and after hot extrusion of the 3D printer nozzle showed a significant increase in the mechanical properties of the hot‐extruded filaments. In addition, the mechanical characterization of 3D printed parts showed that increasing the number of contours can improve the mechanical properties of parts, while the raster angle can have a complex effect. The mechanical properties of the parts are also improved by reducing the temperature of the nozzle and the build platform. Printing speed, as an essential parameter in AM, was related to the previously mentioned parameters, and the results showed that increasing the printing speed could improve the UTS and Young's modulus of the 3D printed part.Highlights A novel biodegradable polymer (HAVOH) was introduced into the scope of FFF. The hot extruded G‐Polymer filament from the nozzle showed improved mechanical properties. 180°C nozzle and room temperature platform resulted in improved mechanical properties. 3D printed parts with +45°/−45° raster angle show improved mechanical properties 110 mm/s print speed results in higher mechanical strength than 70 mm/s print speed.

Application of Fractal Formalism for Express Analysis of Mechanical Properties of Parts

Application of Fractal Formalism for Express Analysis of Mechanical Properties of Parts

Influence of contour processing parameters on porosity, surface roughness, and fatigue life in laser powder bed Al-10Si-0.4Mg

Additive manufacturing (AM) enables fabrication of net-shape components with high geometric complexity, however mechanical properties of parts with as-fabricated surfaces are limited by surface roughness and subsurface porosity that may initiate fatigue cracks. This study aims to improve the utility of parts with as-fabricated surfaces by quantifying processing-surface condition-fatigue performance relationships, optimizing surface contour parameters for fatigue performance, and investigating the application of surface profilometry as a non-destructive quality control method. Eleven contour parameter sets of varying energy densities were produced in three classifications: no contour passes, single contour passes, and contours with secondary healing passes. Surface roughness was evaluated using line scan profilometry and subsurface porosity by optical microscopy. Contouring reduced the average surface roughness from Ra ≅ 25 μm to Ra ≅ 5 μm, and the layer of subsurface porosity introduced by this process could be partially eliminated by a secondary healing pass. One set of processing conditions from each contour class was selected for fatigue studies (R = -1), and their results were compared with the fatigue data from machined and polished specimens to evaluate the relative influence of surface condition. Relative to machined and polished specimens, fatigue lives are approximately five times lower for contoured specimens (with and without a healing pass) and twenty times lower for non-contoured specimens at equivalent stress levels up to 107 cycles to failure. Fractographic measurements of initial defect √area of all specimens reveal that fatigue behavior is well characterized by stress intensity factor amplitude across all surface conditions. An extreme value statistical method is developed using profilometry data to predict S-N curves, and it is concluded that non-destructive surface roughness measurements may be suitable for estimating the fatigue lives of components with as-fabricated surfaces as a rapid method for quality control.

Studying the effects of FDM process parameters on the mechanical properties of parts produced from PLA using response surface methodology

Studying the effects of FDM process parameters on the mechanical properties of parts produced from PLA using response surface methodology

Study of the influence of additive manufacturing applicable surface treatment methods on mechanical part properties for use in aerospace applications

The adequate assessment of the quality of parts produced by additive manufacturing is crucial for their application in the aviation industry. Therefore, parameters of the manufacturing process, which influence the part quality, have to be identified and quantified to reveal existing correlations. Besides, it is essential to gain an overall understanding of the influence of each step in the additive manufacturing chain, including also post-process treatments and inspection methods, on the data, which is used to develop a statement about the additively manufactured parts’ quality. The present study aims on forming such a comprehensive picture. For this purpose, 120 test specimens from AlSi10Mg were manufactured on an EOS M 290. Four different surface treatments (centrifugal blasting, barrel finishing, abrasive flow machining and turning & polishing) were applied to the specimens and compared to the as-built condition regarding the resulting material properties. The relative density, surface roughness, surface hardness, ultimate tensile strength, yield strength, Young’s modulus and the fatigue properties were determined and analysed especially for correlations with the surface treatment and specimen positions in the build space. The surface roughness, fatigue properties and static tensile properties showed to be dependent on the applied surface treatment, while fewer correlations could be found regarding the surface hardness and relative part density. No clear indication was found relating one of the mentioned properties to certain areas in the build space.

Effect of the Number of Shells on Selected Mechanical Properties of Parts Manufactured by FDM/FFF Technology

Abstract The technological parameters of 3D printing have an influence on the mechanical properties of the manufactured components. The purpose of the article was to study the comparative influence of the technological parameter of the number of shells variable in two stages (2 and 10) on selected mechanical properties. The maximum tensile stress for the number of shells 10 was 39.80 MPa, which is higher compared to the number of shells 2: 30.98 MPa. In the case of the maximum bending stress for the number of shells 10, an average value of 61.02 MPa was obtained, which is higher compared to the number of shells of 2: 37.46 MPa. Furthermore strong fit of the Kelvin-Voight model was obtained, as confirmed by the values of the Cℎi 2: 0.0001 and R 2: 0.997 coefficients.

Additive manufacturing of thermoplastic elastomer structures using dual material core-shell filaments

Filament-based flexible material extrusion additive manufacturing is highly desirable yet faces critical challenges such as limited print resolution and repeatability. To enhance printability of a thermoplastic elastomer (TPE), a series of core-shell filaments comprising a TPE shell (Shore hardness 75 A) and a rigid ABS core are fabricated, with the ABS volume fraction varying from 11% to 78%. The presence of an ABS core imparts rigidity to the filament to inhibit buckling and allow for successful high-fidelity 3D printing. Rheological characterizations of TPE and ABS using capillary and parallel-plate viscometry point to the optimized extrusion parameters suitable for filament coextrusion, printability, and wettability between the print interfaces. Complex benchmark geometries are printed to verify the print resolution. Printed specimens with less than 20% ABS preserve the shore hardness of 75 A, providing flexibility and a soft touch to the printed structures. Izod impact, 3-point bending, and tensile tests reveal tunable mechanical properties of parts printed in z-direction with ABS+TPE filaments. Lower ABS content exhibits higher flexibility and impact resistance, while higher ABS imparts higher stiffness and tensile strength. Notably, the parts printed with 30–40% ABS exhibit higher toughness and impact strength than specimens composed of ABS or TPE alone. Lastly, a coil spring printed with a ABS+TPE filament exhibits reversible extension up to 120 mm, at least twice the reversible extension of an ABS-printed coil spring.

The columnar dendrite and equiaxed dendrite transformation of high Nb-TiAl alloy by laser-directed energy deposition

Laser-directed energy deposition (LDED) is a significant method for shaping high Nb-TiAl alloys. The dendrite type has an impact on the mechanical properties of parts fabricated with LDED. This study establishes a dendrite transformation model for the alloy. The refinement mechanism of microstructure and the strengthening mechanism of high-temperature mechanical properties are analyzed through experiment and simulation. The results show that the scanning rate has a significant influence on the dendrite type. Modifying the scanning rate brings about a gradual decrease in the G/R (where G denotes temperature gradient and R is the growth rate) value of the molten pool, and a concurrent gradual increase in the value of G×R. These changes facilitate the transformation of columnar dendrites into equiaxed dendrites. Furthermore, the lamellar colony size is reduced by 72.8% and the tensile strength at 900 °C is increased by 16.2%. Microstructure refinement is the primary reason for the enhancement of high-temperature tensile characteristics, with dislocations and deformation twins also contributing to crack propagation resistance.

Throughput scaling and thermomechanical behaviour in multiplexed fused filament fabrication

Multiplexed Fused Filament Fabrication (MF3) combines a dynamic extrusion-based toolpath with a multi-extruder-single-gantry machine tool architecture to increase printing speed without sacrificing geometric capabilities or increasing hardware complexity. This work establishes a novel capability for geometrically generalizable synthesis of MF3 toolpaths and creates a new thermal model that incorporates the unique nature of material deposition. It is shown that MF3 can increase throughput by an order of magnitude or more via the atypical and nonlinear effects of part size, infill density and extruder spacing. Further, the unusual temperature history in MF3 is found to enhance the part's mechanical properties.

Optimization of Rheology Parameters for Feedstock by Powder Injection Molding (PIM) Via Taguchi Analysis

The most critical process in the powder injection molding method is determining the powder/binder rate and its properties. The most important feature that distinguishes the powder injection molding method from other powder metallurgy production methods is its advantage in producing high raw density and complex shaped parts. However, providing these advantages includes a multi-parameter process that directly affects the injection molding parameters and the final part's mechanical properties. In addition, the difficulty of experimental studies causes energy, time, and cost losses in determining the powder/binder rate and rheological properties of the feedstock so that the advantages of the method turn into a manageable disadvantage. This study performed rheology studies for three different feedstocks (PW/CW/SA, PW/PE/SA, and PEG8000/PP/SA). In this context, this paper determined the rheological properties of different feedstocks to take advantage of the Taguchi analysis. Flow behavior index, viscosity and optimum loading rates were determined separately for all feedstocks. The results exhibited the injection molding can be done with the determined best (58% steatite+PEG8000/PP/SA) F3 feedstock by volume. Based on it was found that viscosity and melt flow index were not a problem for injection molding in three different feedstocks used in the result, advantages and disadvantages were observed.

A novel method for measurements of surface topography in previously inaccessible areas

Abstract Since mechanical properties of parts in mechanical engineering are influenced in many ways by their surface structure, detailed knowledge of the surface structure is essential for predicting and describing these properties. Tactile and optical measurement methods are well established but cannot always reach every area of a part due to geometric constraints. To enable measurements in these areas, a method utilizing impressions and a laser scanning microscope is proposed. It is easy to use and able to correctly reproduce surface structures of technical surfaces, which is proven by a comparison of original parts and impressions of three surface areas on an example specimen. Two application examples from the domain of fatigue strength tests are shown. The surface structure is measured directly in the notch radius of shaft shoulders and inside hollow shafts made in different manufacturing processes. Utilizing modern optical measurement instruments, the proposed method enables accurate measurements of surface structure in previously inaccessible areas.

Investigation of Mechanical Properties of Part Produced By Selective Laser Sintering

It is possible to build physical models, prototypes, components, tools, and functioning parts from 3D data created using a computer (CAD), with sophisticated geometry, using Additive Manufacturing - AM, which is difficult or impossible to perform with traditional manufacturing methods. Metals, ceramics, and polymers in the form of liquids, powders, wire, foil, and other materials are used in AM techniques to create prototypes. However, there are several constraints, the most significant of which being the material selection. As a result, it is critical to understand material qualities and how machine settings affect them, especially if the machine is producing functioning components. The influence of component placement (X and Y direction) in the build on the dimensional accuracy and mechanical qualities of parts produced by this SLS method will be investigated in this research.