Multi-Physics Coupling Modeling and Experimental Investigation of Vibration-Assisted Blisk Channel ECM

Due to its advantages of good surface quality and not being affected by material hardness, electrochemical machining (ECM) is suitable for the machining of blisk, which is known for its hard-to-machine materials and complex shapes. However, because of the unstable processing and low machining quality, conventional linear feeding blisk ECM has difficulty in obtaining a complex structure. To settle this problem, the vibration-assisted ECM method is introduced to machine blisk channels in this paper. To analyze the influence of vibration on the process of ECM, a two-phase flow field model is established based on the RANS k-ε turbulence model, which is suitable for narrow flow field and high flow velocity. The model is coupled with the electric field, the flow field, and the temperature field to form a multi-physics field coupling model. In addition, dynamic simulation is carried out on account of the multi-physics field coupling model and comparative experiments are conducted using the self-developed ECM machine tool. While a shortcut appeared in the contrast experiment, machining with vibration-assisted channel ECM achieved fine machining stability and surface quality. The workpiece obtained by vibration-assisted channel ECM has three narrow and straight channels, with a width of less than 3 mm, an aspect ratio of more than 8, and an average surface roughness Ra in the hub of 0.327 μm. Compared with experimental data, the maximum relative errors of simulation are only 1.05% in channel width and 8.11% in machining current, which indicates that the multi-physics field coupling model is close to machining reality.

Effects of Particle Size and Composite Composition of Carbon Microparticles as Reinforcement Components on Resin-Based Brake Pad Performance

This study aims to investigate the effect of particle size and composition of bamboo and clove leaves as reinforcement components on resin-based brake pad performance. Bamboo fibers contain cellulose and lignin, making them better mechanical properties compared to glass fibers. Clove leaves due to their containment of oil components can be used, playing roles in binding bamboo with resin material. In short, experiments were done by involving polymerization of polyester resin as an adhesive with methyl ethyl ketone peroxide (MEKP) at room temperature. The composition of polyester/MEKP/reinforcing components was fixed at a mass ratio of 10/1/1.76 and the particle size of the reinforcing components were 582 and 250 m. Reinforcing components were mixed carbonized bamboo fiber and dried clove leaves with a ratio of 4/1; 7/1; and 10/1. The results showed that smaller particles has better mechanical properties, and the more amount of bamboo particles give positive impacts on the material hardness. The best hardness value (reaching 24 N/cm2) and smallest pore volume (0.0213 cm3) were obtained when using the ratio of 10:1. While the smallest weight loss of mass at the rate of 0.1225 g/min was obtained by the ratio of 7/1. The largest friction coefficient and lowest wear rate were obtained by 4/1 with a value of 0.1108 and 1.08 g/s.mm2, respectively. This study demonstrates the use of biomass waste such as bamboo fiber and dried clove leaves as an alternative to asbestos and reduces the abundant waste of bamboo powder and dried clove leaves in Indonesia.

Printing People. Heterogeneous Multi-Property Printing of Humanoid Anatomics

<p>Film and television (TV) have been a way to view unthinkable worlds for many years. Physical props are a fundamental part of many films as they help to portray the story in the real world, which results in a more believable experience for the audience. The technology used in the production of props and creatures has evolved with the changes in the manufacturing process to allow for more computer-controlled designs. This begs the question; what could multi-property, 3D/4D printing bring to the way the film prop manufacturing industry creates physical props? Printing in the fourth dimension (dynamic) is a relatively new concept and is being researched by leading 3D printing companies. This area of study has yet to apply the four-dimensional (4D) capabilities of multi-property printing to the creation of heterogeneous humanoid anatomic’s. Heterogeneous 3D printing is the combination of multiple elements and material qualities in one print, which is possible by using the Stratasys J750 Polyjet printer. This printer allows for both hard and soft components to be incorporated into one design by blending the full-colour hard Vero material with soft, translucent Agilus material. The final humanoid objects have varying material hardness throughout the design, representing the different densities and materiality that is found in the finger joint. By taking the basic parameters of a section of human anatomy, the ability to create a creature by merely changing the size, colour, or the number of joints is achievable. With this technology, the ability to rapidly produce and easily edited final on-screen props is possible.</p>

Printing People. Heterogeneous Multi-Property Printing of Humanoid Anatomics

<p>Film and television (TV) have been a way to view unthinkable worlds for many years. Physical props are a fundamental part of many films as they help to portray the story in the real world, which results in a more believable experience for the audience. The technology used in the production of props and creatures has evolved with the changes in the manufacturing process to allow for more computer-controlled designs. This begs the question; what could multi-property, 3D/4D printing bring to the way the film prop manufacturing industry creates physical props? Printing in the fourth dimension (dynamic) is a relatively new concept and is being researched by leading 3D printing companies. This area of study has yet to apply the four-dimensional (4D) capabilities of multi-property printing to the creation of heterogeneous humanoid anatomic’s. Heterogeneous 3D printing is the combination of multiple elements and material qualities in one print, which is possible by using the Stratasys J750 Polyjet printer. This printer allows for both hard and soft components to be incorporated into one design by blending the full-colour hard Vero material with soft, translucent Agilus material. The final humanoid objects have varying material hardness throughout the design, representing the different densities and materiality that is found in the finger joint. By taking the basic parameters of a section of human anatomy, the ability to create a creature by merely changing the size, colour, or the number of joints is achievable. With this technology, the ability to rapidly produce and easily edited final on-screen props is possible.</p>

The Effect of Temper Condition and Feeding Speed on the Additive Manufacturing of AA2011 Parts Using Friction Stir Deposition

In the current study, solid-state additive manufacturing (SSAM) of two temper conditions AA2011 was successfully conducted using the friction stir deposition (FSD) process. The AA2011-T6 and AA2011-O consumable bars of 20 mm diameter were used as a feeding material against AA5083 substrate. The effect of the rotation rate and feeding speed of the consumable bars on the macrostructure, microstructure, and hardness of the friction stir deposited (FSD) materials were examined. The AA2011-T6 bars were deposited at a constant rotation rate of 1200 rpm and different feeding speeds of 3, 6, and 9 mm/min, whereas the AA2011-O bars were deposited at a constant rotation rate of 200 mm/min and varied feeding speeds of 1, 2, and 3 mm/min. The obtained microstructure was investigated using an optical microscope and scanning electron microscope equipped with EDS analysis to evaluate microstructural features. Hardness was also assessed as average values and maps. The results showed that this new technique succeeded in producing sound additive manufactured parts at all the applied processing parameters. The microstructures of the additive manufactured parts showed equiaxed refined grains compared to the coarse grain of the starting materials. The detected intermetallics in AA2011 alloy are mainly Al2Cu and Al7Cu2Fe. The improvement in hardness of AA2011-O AMPs reached 163% of the starting material hardness at the applied feeding speed of 1 mm/min. The hardness mapping analysis reveals a homogeneous hardness profile along the building direction. Finally, it can be said that the temper conditions of the starting AA2011 materials govern the selection of the processing parameters in terms of rotation rate and feeding speed and affects the properties of the produced additive manufactured parts in terms of hardness and microstructural features.

Investigation of Uneven Properties of Stainless Steel 12Kh18N10T Depending on the Thickness of the Sheet

The authors conduct the research of the properties of a cold-rolled sheet made of corrosion-resistant steel 12Kh18N10T of a variable thickness. Further, they build hardening curves and defined their coefficients. The research identifies the patterns of the thickness impact on the nature of hardening of the sheet material 12Kh18N10T. The authors conduct the measurements of micro-hardness along the sheet thickness. The article confirms the suggestion that hardness in the sheet center decreases for various thicknesses. The authors further present a comparative analysis of hardness values distribution for the corrosion-resistant steel 12Kh18N10T and steel containing 0.08% of carbon. It is revealed that lower material thickness alters the strength parameters of the process and increases the mean material hardness. The authors provide the hardening curves for various sheet thicknesses and the dependence of hardness distribution on the thickness of these sheets.

Relationship between Processing Parameters, Product Dimensions, and Wave Strain Hardening

This article considers the influence of the size of processed workpieces during their strain hardening based on the impact of deformation waves on the processed surface. For the first time, the specificity of the hardened layer formation by wave strain hardening (WSH) makes it possible to draw attention to the fact that, with equal volumes of hardened samples and processing modes, different diagrams of microhardness distribution in the surface layer are observed. The aim of this work is to establish the relationship between processing parameters, workpiece dimensions, and the WSH nature for the first time. The experiments are carried out on a specially designed bench. It is established that WSH occurs not only from the front side (along which the processing was performed), but also from the back side, while leaving the original material hardness in the middle of the sample. The results obtained form a basis for the further development of WSH technology.

Correlation Modeling Between Peening-Induced Hardness, Residual Stress and Roughness in Case-Hardened High Strength Steels

The present paper is focused on the investigation of the correlation modeling of hardness and compressive residual stress on the surface and subsurface regions of case-hardened 18CrNiMo7-6 steels subjected to shot peening. The results exhibit that the relationship between hardness and compressive residual stress can reasonably well be approximated by an inverse linear model. The analysis suggests that the slope and y-intercept of the inverse linear trend line can be related to the compressive residual stress level and the initial material hardness, respectively. It is further revealed that the negative effect brought by the peening-induced roughness on the measurement of experimental data computed on the surface can be compensated by performing the normalization using the roughness parameter called the maximum valley height (Sv).

Structure and Mechanical Properties of Laser Powder Bed-Fused and Wrought PH13-8Mo-Type Precipitation Hardening Stainless Steels: Comparative Study

This work focuses on the structure and properties of a laser powder bed-fused (LPBF) precipitation hardening stainless steel and its chemically analogous wrought counterpart, both subjected to an identical combination of solution and aging treatments with the objective of maximizing the material hardness. It was observed that both the LPBF and wrought alloy follows similar evolution of their phase composition, microstructure, and mechanical properties throughout the different stages of the technological workflow. After a solution treatment at 850 °C for 0.5 h and an aging at 525 °C for 2 h, both alloys achieve their highest hardness of ~50 HRC. Notwithstanding this similarity, the LPBF alloy offers a finer microstructure and a lower amount of retained austenite than its wrought counterpart. This microstructure provides comparable strength characteristics to both the LPBF and wrought alloys, while offering a significantly higher ductility to the former as compared to the latter. The elongation at break of the LPBF alloy is, however, strongly build orientation-dependent, with a measured anisotropy of 23%. This anisotropy is caused by the presence of processing-induced pores (average pore size ~23 µm) in the LPBF alloy preferably distributed in planes oriented perpendicular to the build direction.