scholarly journals Examples of controlling the technological stress state characteristics of layer-by-layer manufactured products in the framework of the accreted solid model

2021 ◽  
Vol 1902 (1) ◽  
pp. 012019
Author(s):  
D A Parshin
Keyword(s):  
Stress State ◽  
Solid Model ◽  
Layer By Layer ◽  
Manufactured Products ◽  
Technological Stress

TECHNOLOGICAL CONTROL OF THE CONTACT PRESSURE ON THE CYLINDRICAL SUBSTRATE FROM THE SIDE OF THE COATING ADDITIVELY FORMED ON ITS EXTERNAL SURFACE

2020 ◽  
Author(s):  
Dmitriy Parshin
Keyword(s):  
Stress State ◽  
Contact Pressure ◽  
Mechanical Model ◽  
External Surface ◽  
Layer By Layer ◽  
Layer Formation ◽  
Technological Control ◽  
Manufactured Products ◽  
Arbitrary Thickness

The article gives an example of controlling the stress state parameters of additively manufactured products. The study was carried out on the basis of a developed non-classical mechanical model of the process of layer-by-layer formation of a coating of arbitrary thickness on a cylindrical substrate. The model is based on modern concepts of the mechanics of continuously growing bodies and allows one to obtain fairly simple analytical dependencies. On the basis of the latter, the problem of technological control of the evolution of contact pressure at the substrate – coating interface is solved in the article. A number of practically significant conclusions have been made.

Mortar for 3D Printing Based on Gypsum Binders

2021 ◽  
Vol 1037 ◽  
pp. 26-31
Author(s):  
Ekaterina Potapova ◽  
Tatiana Guseva ◽  
Kirill Shchelchkov ◽  
Hans Bertram Fischer
Keyword(s):  
3D Printing ◽  
Structural Design ◽  
High Speed ◽  
High Viscosity ◽  
Solid Model ◽  
3D Printer ◽  
Layer By Layer ◽  
Adhesive Properties ◽  
Binding Material ◽  
Complex Shapes

3D construction printer - is an innovative construction approach with which building elements can be constructed without the use of formwork and you to get products of various complex shapes with minimal time and material costs. Binder 3D printing technology results in a cheap and high-speed construction method that allows greater freedom in both architectural and structural design of concrete. The principle of operation of a 3D printer is based on the principle of gradual (layer-by-layer) creation of a solid model, which is, as it were, "grown" from a certain binding material. The working mixture must have thixotropic and adhesive properties, it must be workable by the printer and at the same time not spread under the influence of subsequent layers. Therefore, it is important to select the composition of the composition of the working mixture. This paper presents the results of a study on the development of the composition of a working mixture based on a gypsum-cement-pozzolanic binder. The developed composition of the gypsum-cement-pozzolanic binder with a complex of modifying additives is characterized by low spreadability, high viscosity and is easy to lay.

The Design of Artificial Porous Human Bone and RP Procedure Simulation

2011 ◽  
Vol 58-60 ◽  
pp. 1277-1281
Author(s):  
Xin Rui Gao
Keyword(s):  
Porous Structure ◽  
Human Bone ◽  
Solid Model ◽  
Layer By Layer ◽  
Artificial Bone ◽  
Java 3D ◽  
Laser Head ◽  
Artificial Bones ◽  
Voxel Model

In design of artificial bones, in order to make it live together with the human bone, it should has the same porous structure as the human bone. But the Brep or solid model can’t achieve this. By transforming the three direction DEXEL model of polyhedrons into its VOXEL model and setting transparency attributes of VOXELs, the porous structure of artificial bone could be designed. By merging the same attribute VOXELs along y axis, a big VOXEL is formed. By this big VOXEL, the once sintering procedure of RP laser head is simulated. Layer by layer, the whole product is produced. Under Java2.0 and Java 3D, these algorithms were tested and some design examples were given.

Estimation of residual stress level in plasma coatings of increased thickness

2020 ◽  
pp. 122-131
Author(s):  
Igor N. Kravchenko ◽  
Tatyana A. Chekha ◽  
Boris A. Bogachev ◽  
Yuriy A. Shamarin
Keyword(s):  
Mathematical Model ◽  
Stress State ◽  
Residual Stresses ◽  
Flow Rate ◽  
Material Flow ◽  
Plasma Torch ◽  
Thermal State ◽  
Research Purpose ◽  
Base System ◽  
Layer By Layer

Regulation of the thermal and stress state of the “coating-base” system is an important step of the coatings quality management and is carried out by changing the thermal power of the plasma jet per unit of the sprayed surface by controlling the movement velocity of the plasma torch and the sprayed material flow rate. (Research purpose) The research purpose is development of a mathematical model that describes the process of layer-by-layer coatings formation and the change in the thermal state of the coating-base system during plasma spraying. (Materials and methods) We have used finite differences, finite elements and marching for solving the thermal and strength problems in internal stresses determining. We have used a technique for determining thermal fields, considering the dependence of thermal-physical and mechanical properties of the coating and base materials on temperature, the occurrence of plastic deformations and stress relaxation. A mathematical model has been designed for calculating a thermal field with a moving boundary considering the nonlinear nature of coating growth during layer-by-layer deposition and the dependence on the thermophysical properties of the coating-base system materials. We have substantiated the method that allows eliminating the existing shortcomings of traditional technologies for design and experimental studies of the thermal and stress state of the coating-base system, as well as automatization of the process of solving the numerical model and increasing the efficiency of the entire research cycle. (Results and discussion) It was found that when the flow rate of the sprayed material is changed from 0.1 to 1.0 grams per second and the plasma torch travel velocity is from 10 to 350 millimeters per second, the residual stresses in PG-19M-01 coatings on steel change their sign and can be both compressive and tensile. Varying the coating conditions allows reducing the level of residual stresses by 3-5 times. The article shows that a decrease in the level of residual stresses corresponds to an increase in the coating adhesion strength at a constant mass average temperature of the particles during the deposition process and is achieved by controlling the sprayed material flow rate and the plasma torch velocity, pre-heating the substrate and cooling. (Conclusion) It was found that the use of the proposed model makes it possible to evaluate the effect of the parameters of the spraying process (plasma torch travel velocity, spray material consumption, thermal state of the substrate before spraying, cooling conditions during spraying) on the residual stresses level.

Stress Analysis of the Human Skull due to the Insertion of Rapid Palatal Expander with Finite Element Analysis (FEA)

2008 ◽  
Vol 399 ◽  
pp. 211-218 ◽  
Author(s):  
Laurenţiu Culea ◽  
Cristina Bratu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress State ◽  
Stress Analysis ◽  
Solid Model ◽  
Element Analysis ◽  
Human Skull ◽  
3D Cad ◽  
Ct Slices

The study aims at analyzing the stress state of the human skull with FEA, simulating the loads due to the insertion of rapid palatal expanders with two or four arms. A 3D CAD solid model of a human skull has been created starting from CT slices. Using FEA, forces that simulate the loads developed by the expander have been applied to the solid model of the skull to determine the stress state.

Hopping Barriers at Step Edges

1993 ◽  
Vol 312 ◽  
Author(s):  
Pavel Šmilauer ◽  
Mark R. Wilby ◽  
Dimitri D. Vvedensky
Keyword(s):  
High Energy ◽  
Layer Growth ◽  
Low Energy ◽  
Step Edge ◽  
Solid Model ◽  
Layer By Layer ◽  
Ion Sputtering ◽  
High Energy Electron ◽  
Diffraction Intensity ◽  
Good Agreement

AbstractThe recent discovery of reentrant layer-by-layer growth in metal homoepitaxy has stimulated considerable interest in the role played by barriers to hopping down descending steps. However, the existence of step-edge barriers for semiconductors is far from being clearly established. We have investigated the effects of step-edge barriers for epitaxial growth and the “inverse” process of low-energy ion sputtering on metal surfaces using Monte Carlo simulations of a solid-on-solid model. Our results are in good agreement with available experimental data and provide new insights into the microscopic origins of the evolution of surface morphology during these processes. Our simulations also suggest that such step-edge barriers can explain the observed temperature and time dependence of the reflection high-energy electron diffraction intensity during post-growth recovery on GaAs(001), which sheds new light on this controversial subject.

CREEP OF INHOMOGENEOUS POLYMER CYLINDRICAL SHELL DURING HEATING

2021 ◽  
pp. 33-39
Author(s):  
V.I. Andreev ◽  
◽  
S.A. Sereda ◽  
Keyword(s):  
Differential Equation ◽  
Cylindrical Shell ◽  
Temperature Field ◽  
Stress State ◽  
Nonlinear Problem ◽  
Plane Deformation ◽  
Elastic Solution ◽  
Layer By Layer ◽  
Layer Method ◽  
Significant Difference

Abstract. The article deals with the problem of creep of a polymer thick-walled cylindrical shell under the action of an uneven temperature field. The calculation is based on the nonlinear Maxwell – Gurevich equation, which is widely used in the calculations of polymer structures. To solve a quasi-stationary nonlinear problem, a "layer-by-layer" method is used, where a layer means a certain time of the process. Such methods for solving creep problems are also called step, sequential loading, incremental, etc. The problem is solved in an axisymmetric formulation under conditions of plane deformation. The use of the Maxwell – Gurevich differential equation allows solving rheology problems when exposed to a timevarying temperature field. The change in the stress state with time and its significant difference from the elastic solution are shown.

Residual Stress in Additive Manufactured Nickel Alloy 625 Parts

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Lindsey Bass ◽  
Justin Milner ◽  
Thomas Gnäupel-Herold ◽  
Shawn Moylan
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Nickel Alloy ◽  
Model Development ◽  
Three Dimensional ◽  
Powder Layer ◽  
Layer By Layer ◽  
Negative Effects ◽  
Alloy 625 ◽  
Development And Validation

One of the key barriers to widespread adoption of additive manufacturing (AM) for metal parts is the build-up of residual stresses. In the laser-based powder bed fusion process, a laser selectively fuses metal powder layer by layer, generating significant temperature gradients that cause residual stress within the part. This can lead to parts exceeding tolerances and experiencing severe deformations. In order to develop strategies to reduce the adverse effects of these stresses, the stresses first need to be quantified. Cylindrical Nickel Alloy 625 samples were designed with varied outer diameters, inner diameters, and heights. Neutron diffraction was used to characterize the three-dimensional (3D) stress state throughout the parts. The stress state of the parts was generally comprised of tensile exteriors and compressive interiors. Regardless of part height, only the topmost scan height of each part experienced large reductions in axial and hoop stress. Improved understanding of the residual stress trends will aid in model development and validation leading to techniques to reduce negative effects of the residual stress.

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