scholarly journals Numerical Modeling of Bond Formation in Polymer Surface Metallization Using Cold Spray

Author(s):  
Asghar Heydari Astaraee ◽  
Chiara Colombo ◽  
Sara Bagherifard

AbstractSurface metallization of polymeric materials using cold spray technology has gained increasing attention in the past decade. Experimental studies have evidenced multiple challenges of this process regarding continuity and homogeneity of the metallic deposits on polymer substrates. Modeling and simulation tools could be very helpful to assess the efficiency of different strategies suggested for improved deposition at a considerably reduced cost; nevertheless, the efforts to use numerical modeling in this sector have been less successful. Here, we develop a detailed finite element model for the cold spray deposition of metal particles on polymeric substrates to shed light on the underlying deposition mechanisms. The simulation results are compared with the literature experiments to establish the effectiveness of the proposed model. The developed model is able to capture the key phenomena involved in the deposition mechanism particularly the particle and substrate mechanical interlocking and substrate local melting. It is shown that a particle velocity threshold value should be exceeded to achieve an effective mechanical interlocking. The substate thermal domain and melting as well as the effects of particle velocity and size on deformation and particle anchorage are discussed.

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1849
Author(s):  
Martin Schmidt ◽  
Stefan Zahn ◽  
Florian Gehlhaar ◽  
Andrea Prager ◽  
Jan Griebel ◽  
...  

Radiation-induced graft immobilization (RIGI) is a novel method for the covalent binding of substances on polymeric materials without the use of additional chemicals. In contrast to the well-known radiation-induced graft polymerization (RIGP), RIGI can use non-vinyl compounds such as small and large functional molecules, hydrophilic polymers, or even enzymes. In a one-step electron-beam-based process, immobilization can be performed in a clean, fast, and continuous operation mode, as required for industrial applications. This study proposes a reaction mechanism using polyvinylidene fluoride (PVDF) and two small model molecules, glycine and taurine, in aqueous solution. Covalent coupling of single molecules is achieved by radical recombination and alkene addition reactions, with water radiolysis playing a crucial role in the formation of reactive solute species. Hydroxyl radicals contribute mainly to the immobilization, while solvated electrons and hydrogen radicals play a minor role. Release of fluoride is mainly induced by direct ionization of the polymer and supported by water. Hydrophobic chains attached to cations appear to enhance the covalent attachment of solutes to the polymer surface. Computational work is complemented by experimental studies, including X-ray photoelectron spectroscopy (XPS) and fluoride high-performance ion chromatography (HPIC).


2021 ◽  
Vol 405 ◽  
pp. 126676
Author(s):  
Xinliang Xie ◽  
Zhanqiu Tan ◽  
Chaoyue Chen ◽  
Yingchun Xie ◽  
Hongjian Wu ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.


2018 ◽  
Vol 941 ◽  
pp. 1639-1644
Author(s):  
Xin Chu ◽  
Phuong Vo ◽  
Stephen Yue

The splat test is usually generated by low feed rate cold spraying of particles onto an as-polished substrate and it can be considered as a monolayer coating deposition. In this study, in order to investigate cold spray deposition mechanisms, Fe splats were sprayed onto the cold-sprayed single component 316L, Fe, and a composite 90Fe coatings. Results showed that although there is only 3.6 vol.% of 316L in the composite 90Fe coating, Fe splats exhibit a much better deposition behavior onto the 90Fe as compared with the single component Fe coating. To explain this observation, Fe splat samples were characterized using the scanning electron microscope (SEM), optical profilometry, splat adhesion tests, and splat nanoindentation. Finally, a preliminary explanation towards the Fe splat deposition behavior onto the composite coating was drawn.


2017 ◽  
Vol 53 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Alexander L Popov ◽  
Sergei E Alexandrov ◽  
Victor M Kozintsev ◽  
Alexander L Levitin ◽  
Dmitri A Chelyubeev

Theoretical, calculated, and experimental results of studies on the registration of the accounting effect of plasticity in the diagnosis of axisymmetric stresses by the hole method and speckle-interferometric detection of the field of normal displacements in its vicinity are presented. Theoretical and computational studies were carried out on a disk model of finite thickness from an ideally elastic–plastic material. The theoretical model considers the formation of elastoplastic deformations in the vicinity of the through hole; the calculated finite element model considers in the vicinity of both through and blind holes of different depths. It was noted that at the blind hole, the most informative are the movements of the axisymmetric bend caused by the violation by the blind hole of symmetry of the disk with respect to its median plane. At the same time, an approximate analytical method has been developed to calculate the stresses that cause only elastic deformations. Experimental studies were carried out on a series of samples in the form of steel disks with axisymmetric stresses near the yield point. These stresses were induced by the hot fit of grinded rings from hardened high-strength steel onto disks made of steel with a low yield strength. Examples are given which show that the stress values determined from normal displacements in the vicinity of the probe holes from the calculated–theoretical and experimental are similar.


Author(s):  
Roghayeh Nikbakht ◽  
Mohammad Saadati ◽  
Taek-Soo Kim ◽  
Mohammad Jahazi ◽  
Hyoung Seop Kim ◽  
...  

Author(s):  
Pan Fang ◽  
Yuxin Xu ◽  
Shuai Yuan ◽  
Yong Bai ◽  
Peng Cheng

Fibreglass reinforced flexible pipe (FRFP) is regarded as a great alternative to many bonded flexible pipes in the field of oil or gas transportation in shallow water. This paper describes an analysis of the mechanical behavior of FRFP under torsion. The mechanical behavior of FRFP subjected to pure torsion was investigated by experimental, analytical and numerical methods. Firstly, this paper presents experimental studies of three 10-layer FRFP subjected to torsional load. Torque-torsion angle relations were recorded during this test. Then, a theoretical model based on three-dimensional (3D) anisotropic elasticity theory was proposed to study the mechanical behavior of FRFP. In addition, a finite element model (FEM) including reinforced layers and PE layers was used to simulate the torsional load condition in ABAQUS. Torque-torsion angle relations obtained from these three methods agree well with each other, which illustrates the accuracy and reliability of the analytical model and FEM. The impact of fibreglass winding angle, thickness of reinforced layers and radius-thickness ratio were also studied. Conclusions obtained from this research may be of great practicality to manufacturing engineers.


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