Complex-shaped Parts Research Articles

Analytical modelling of the behaviour and scatter of the flexural modulus of randomly oriented carbon fibre strand thermoplastic composites

Randomly oriented strand composites are promising materials for complex-shaped parts, especially in the aerospace and automotive industries. However, test data from small specimens tend to have a high level of scatter as these materials contain several centimetres of chopped carbon fibre strands. In this study, we investigated the mechanical properties of ultra-thin chopped carbon fibre tape reinforced thermoplastics (UT-CTT), which contain chopped thermoplastic thin-ply prepreg tapes produced using a paper-making technique. We propose a model for accurately evaluating the flexural modulus and its scatter, which was verified by comparison with experimental data. The predictions of the model showed excellent agreement with the experimental results. This method makes it possible to quantify the scatter of the flexural modulus and is useful for designing geometries of, not only standard test specimens, but also complex parts for actual applications.

Electropolishing Behavior of Additive Layer Manufacturing 316L Stainless Steel in Deep Eutectic Solvents

Additive Layer Manufacturing (ALM) presents many design benefits compared to mechanical machining, particularly for complex shape parts. Significant weight and cost savings are achieved because of the production of near-net-shape metallic parts combined with a lower amount of raw materials. However ALM parts suffer from high roughness, worsening the corrosion resistance and the technical endurance. A post-treatment is then necessary to reach mechanical requirements. Electrochemical polishing, usually performed in harmful solutions, appears as a promising technic to reduce surface roughness. The aim of this study is then to develop a sustainable electropolishing process for 316 L ALM parts by using a Deep Eutectic Solvents (DES) as electrolyte. The best electropolishing conditions were first determined on Cast and ALM samples. After electropolishing, both types of sample exhibit bright and smooth aspects, revealing a high roughness reduction. The pitting corrosion resistance of both materials is also enhanced by this process.

Properties of Powders from Stainless and Heat Resistant Alloys Produced by Gas Dynamic Spray for Manufacturing Parts of Complex Shape

The objects of the study were powders of stainless steel and superalloy obtained gas-dynamic spray in the VIGA 2B (ALD, Germany). It have been investigated the microstructure, structural and phase composition, grain size, physical, chemical and technological properties of powders of alloys obtained by gas-dynamic spray melts.To study the structure and properties of powders of different factions were the used electron microscopy techniques, metallographic, sedimentation, X-ray, energy dispersive analysis, imaging, chemical, and other analytical methods. The powders have a spherical shape, low impurity content, good fluidity and can be used for producing parts by selective laser sintering, slip casting, injection molding, coating plasma and the sintering.

Experimental and numerical investigation of single and bi-layered tube hydroforming using a new sealing technique

Tube hydroforming is a metal-forming technology process with expanding applications, particularly that is growing used in the production of hollow and complex-shaped parts in automotive and aerospace industry. One of the challenges of industrial tube hydroforming processes is the low formability of multi-layered tubes. Friction plays an important role in tube hydroforming due to the high contact pressure between the surface of the die and tube. Friction force affects the tube formability by preventing the material flow toward the deformation zone. In this research, a new sealing method is used to eliminate the internal pressure in the feeding zone. As a result of this, the friction force between the tube and the die is removed from this zone and flowing of the material toward the deformation zone is improved. First, the new sealing method was examined in a free bulge formation of aluminum tubes. The results show that the new sealing method can increase the formability of aluminum tubes by 19% compared with the conventional sealing method. Finite element simulation of the free bulge formation was performed in Abaqus software with different process parameters. During the simulations, the forming limit curve obtained from the experimental tests was used for the prediction of necking. Results showed that increasing of the friction coefficient increases the formability of the aluminum tubes in the new sealing method. In addition to that, the formability of parts was improved in bi-layered tubes by this technique.

Numerical modeling of vacuum-assisted resin transfer molding using multilayer approach

Vacuum-assisted resin transfer molding (VARTM) is a very suitable solution for composite manufacturing industry. It allows the manufacturing of large and complex shape parts at low costs. However, the simulation of this process is complicated due to myriad physical phenomena involved, specifically the strong coupling between the resin flow and the preform compressibility, i.e. hydro-mechanical coupling. Moreover, the use of the distribution medium involves two types of flow: Planar flow and through-the-thickness flow. These flows cannot be considered together by a 2D model. On the other hand, 3D models require an important amount of computation time. This article presents a VARTM modeling approach that takes into account the hydro-mechanical coupling and the coexistence of planar and transverse flows. The proposed modeling approach allows the simulation of the infusion process in the case of multilayer preform with different materials and orientations, including the distribution medium. This model is validated experimentally based on several infusions.

Research Opportunities to Improve Technical and Economic Performance of Freight Car through the Introduction of Lightweight Materials in their Construction

The article highlights the problems associated with the design of freight railway cars. In particular, the analysis of possibilities of application of polymeric materials as a structural material of the body of the cars. The relevance of this article is not in doubt, because the improvement of technical and economic parameters of the cars is one of the main tasks of car building at this time. The article describes the basic methods of manufacturing bodies of freight cars with the use of composite material – fiberglass. In the work carried out detailed analysis of the physic-mechanical properties of composite materials and identify their advantage over steel. As the object of research for tank wagon for transportation of petroleum products and a hopper car for transportation of grain. For the production of boiler tank wagon was chosen as the method of winding, characterized by comparative simplicity and adaptability. To create elements for hopper was chosen as method of deposition, are useful when creating components and parts of complex shape. The work identifies and explains such concepts as wet and dry winding, roving, shaping, reinforcement material. The authors in the specific example proves the possibility of application of composite materials in the body structure freight cars of various configurations. Research conducted in this article can be used to create new models of freight cars and their parts.

Design and integration of WAAM technology and in situ monitoring system in a gantry machine

Wire arc additive manufacturing, WAAM, is a popular wire-feed additive manufacturing technology that creates components through the deposition of material layer-by-layer. WAAM has become a promising alternative to conventional machining due to its high deposition rate, environmental friendliness and cost-competitiveness. In this research work, an adaptation of a gantry machine with in-situ monitoring and a control system has been carried out, in order to expose the ability of the WAAM technology to fabricate complex-shaped parts. The retrofitting of the machine has been done in several layers called respectively hardware, control and software layers. For the validation of the implemented system, a stainless steel 316L demonstrator has been manufactured, and the required stages have been employed, including part design (CAD), process parameters selection, tool-path definition (CAM) and part manufacturing. This study has shown the feasibility of the adapted machine for additive manufacturing as a controlled process.

Измерение профилей деталей сложной формы с помощью сканирующего нанотвердомера

Измерение профилей деталей сложной формы с помощью сканирующего нанотвердомера

Fibre laser nitriding of titanium and its alloy in open atmosphere for orthopaedic implant applications: Investigations on surface quality, microstructure and tribological properties

Laser nitriding is known to be an effective method to improve the surface hardness and wear resistance of titanium and its alloys. However, the process requires a gas chamber and this greatly limits the practicability for treating orthopaedic implants which involve complex-shaped parts or curved surfaces, such as the tapered surface in a femoral stem or the ball-shaped surface in a femoral head. To tackle this problem, a direct laser nitriding process in open atmosphere was performed on commercially pure titanium (grade 2, TiG2) and Ti6Al4V alloy (grade 5, TiG5) using a continuous-wave (CW) fibre laser. The effects of varying process parameters, for instance laser power and nitrogen pressure on the surface quality, namely discolouration were quantified using ImageJ analysis. The optimised process parameters to produce the gold-coloured nitride surfaces were also identified: 40W (laser power), 25mm/s (scanning speed), 1.5mm (standoff distance) and 5bar (N2 pressure). Particularly, N2 pressure at 5bar was found to be the threshold above which significant discolouration will occur. The surface morphology, composition, microstructure, micro-hardness, and tribological properties, particularly hydrodynamic size distribution of wear debris, were carefully characterized and compared. The experimental results showed that TiG2 and TiG5 reacted differently with the laser radiation at 1.06μm wavelength in laser nitriding as evidenced by substantial differences in the microstructure, and surface colour and morphology. Furthermore, both friction and wear properties were strongly affected by the hardness and microstructure of titanium samples and direct laser nitriding led to substantial improvements in their wear resistant properties. Between the two types of titanium samples, bare TiG2 showed higher friction forces and wear rates, but this trend was reversed after laser nitriding treatments.

Simulation and prediction of the development of dynamic recrystallization during the deformation of low-alloy low-carbon steel blanks

The results of physical modeling of plastic forming using a torsional plastometer are used to analyze the effect of the temperature–deformation parameters on the development of dynamic recrystallization in a low-alloy low-carbon steel. A technique is proposed to predict the structure formation in zones with a heterogeneous state of stress, and it is based on the results of numerical simulation and physical modeling. This technique can be applied to optimize the process of plastic forming and the subsequent finishing treatment of complex-shape parts.

Measurement of the Appearance and Growth of Tow Buckling Defect in the Frame of Complex Shape Manufacturing Process by Using Fringe Projection Technique

AbstractDuring the manufacturing of composite complex shape parts, defects such as tow buckles characterised by out of plane elevation may appear. The parameters controlling the appearance and growth of the defect are not completely understood and need to be investigated. A device capable of reproducing tow buckles has been used to study the tow buckling phenomenon. Several techniques able to measure out of plane elevations are discussed to detect the appearance and evaluate continuously the growth of the tow buckle in relation to its size and shape. The fringe projection technique was chosen as it gives the best compromise between the size of the defect to measure and its resolution.If the in‐plane bending angle is the main criterion at the origin of the tow buckle appearance and growth, it is not the only one. This work shows that the fabric architecture such as the space between the tows perpendicular to the one showing the buckle is also crucial to control the buckle's appearance and growth. It also shows that the differential bi‐axial loading of the fabric as well as the stiffness of the tows in the three main directions greatly influences the appearance of the defect.

Two-Component Metal Injection Moulding of Ti-6Al-4V and Stainless Steel Bi-Material Parts

Two-component metal injection moulding (2C-MIM) allows producing functionally graded metal parts of complex shape by co-sintering. Until now several studies have demonstrated that different material properties can be combined. Another promising material combination is titanium and iron-based materials. It can combine the biocompatibility and low density of titanium with a ductile and cost efficient stainless steel. However, co-sintering these materials reveals challenges due to a significant mismatch in sintering shrinkage and limitations in sintering temperature for both materials. The recent study showed that Ti-6Al-4V can be joined to the stainless steel 316L by 2C-MIM provided that certain constraints are taken in account. The quality of the interface before and after co-sintering is a crucial factor for intact parts after processing. By applying sinterdilatometry the mismatch in shrinkage was compensated by using adjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle was defined with regard to the sintering characteristics of both materials. The developed two-component specimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interface and a tensile strength of 282 MPa after co-sintering.

A sacrificial material approach for spark plasma sintering of complex shapes

An optimized process for the densification of a complex shape part is studied. Production of samples with a complex shape is very difficult in uniaxial die compaction processes because of the thickness differences responsible for densification inhomogeneities. To solve this problem in the case of a particular shape, we propose a solution consisting of homogenization of the shrinkage distances by means of the use of a sacrificial material. This solution was first studied by a finite element approach and then tested experimentally. We obtained a part of complex shape with an overall relative density of 99% and a homogeneous microstructure.

Магнитопорошковый контроль деталей сложной формы в процессе эксплуатации

Магнитопорошковый контроль деталей сложной формы в процессе эксплуатации

Трехмерная печать металлических объемных изделий сложной формы на основе сварочных плазменно-дуговых технологий (Обзор)

Трехмерная печать металлических объемных изделий сложной формы на основе сварочных плазменно-дуговых технологий (Обзор)

3D-printing of metallic volumetric parts of complex shape based on welding plasma-arc technologies (Review)

3D-printing of metallic volumetric parts of complex shape based on welding plasma-arc technologies (Review)

3D gel-printing—An additive manufacturing method for producing complex shape parts

A new 3D printing process, 3D gel-printing (3DGP) based on methaerylate-2-hydroxy ethyl (HEMA) gelation system, was proposed in this paper, and as an example, 316L stainless steel gear was prepared by 3DGP. The rheological behavior of metal slurry, the surface roughness and strength of green sample and sintered sample were researched. The results show that the metal slurry with a 316L particle content of 62.5vol% can be prepared with a HEMA-based gelation system, whose rheological behavior is fit for printing. Catalyst can accelerate the gelation so that complex shape of parts could be setting in time during printing. The green sample has a strength of 16.1±2.2MPa and a roughness of 3.5±0.5μm on top surface. The sintered sample has a homogeneous microstructure and no interface between the printed layers and lines was observed. The sintered sample has a roughness of 3.8±0.9μm on top surface and a tensile strength of 488±15MPa. Generally, 3DGP based on HEMA gelation system is a promising method for producing complex shape parts.

Improving Surface Roughness of Steel Parts XC48 by Tribofinishing Process

The present paper examines the influence of the tribofinishing process on the surface state of steel parts XC48, while taking into account the variation in hardness and mass. The tribofinishing process is a mechanical-chemical process, which comprises the use of low frequency impact vibration in the presence of abrasive and chemical additives [1]. The treatment regime (frequency and amplitude) has a great influence on geometrical, mechanical and metallographic treated surfaces. The improvement of the surface quality is determined as a function of the treatment time from 30 to 240 minutes. The tribofinishing process has many technical and economic advantages for the treatment of mechanical parts of simple and complex shapes, which have a better surface finish and improved life of parts etc.

Lathe turning of complex-shaped parts providing desired surface microrelief

The machining of complex parts with surface shaping by different sections of the cutting edge is considered.

Magnesium Powder Injection Molding (MIM) of Orthopedic Implants for Biomedical Applications

Metal injection molding (MIM) has a high potential for the economic near-net-shape mass production of small-sized and complex-shaped parts. The motivation for launching Mg into the MIM processing chain for manufacturing biodegradable medical implants is related to its compatibility with human bone and its degradation in a non-toxic matter. It has been recognized that the load-bearing capacity of MIM Mg parts is superior to that of biodegradable polymeric components. However, the choice of appropriate polymeric binder components and alloying elements enabling defect-free injection molding and sintering is a major challenge for the use of MIM Mg parts. This study considered the full processing chain for MIM of Mg–Ca alloys to achieve ultimate tensile strength of up to 141 MPa with tensile yield strength of 73 MPa, elongation at fracture Af of 7% and a Young’s modulus of 38 GPa. To achieve these mechanical properties, a thermal debinding study was performed to determine optimal furnace and atmosphere conditions, sintering temperature, heating rates, sintering time and pressure.