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1

Accelerations Caused by Underwater Explosions on the Naval Gun Foundation

Szturomski Bogdan, Kiciński Radosław, Milewski Stanisław

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 1

129--141

EN

The manuscript analyzes the impact of a non-contact underwater explosion on the foundation of a 35 mm naval cannon mounted on board a Project 258 minehunter. The finite element method was used to complete the task. Cole's empirical formulas were used to describe the distribution of the pressure wave from the explosion of the TNT charge in water as a function of distance, time, and mass. The hull geometry was reflected based on technical documentation as a shell structure reinforced with beam-bar elements. Devices with large weights were represented as rigid bodies. Simplifications were used to minimize the number of degrees of freedom. The construction of ship's hull is made of non-magnetic austenitic steel. The dynamic characteristics of this steel were determined based on static and dynamic tensile tests. The Johnson-Cook constitutive model was used to describe the material properties of steel. As part of the work, the impact resistance study of marine structures was presented, how it is defined by the existing regulations in the Polish Navy was considered, and the scope of their applicability was given. The scientific innovation of the presented work consists of checking and specifying the guidelines for designing and constructing warships.

2

Investigation of acoustic-plastic constitutive modeling based on Johnson-Cook model and numerical simulation application

Wang Xingxing, Qi Zhenchao, Chen Wenliang

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

605--620

EN

In this paper, a modified acoustic-plastic Johnson–Cook model for Ti–45Nb alloy was established, which can be used to reveal the metallic deformation behavior under ultrasonic vibration-assisted (TUV) forming. First, the experiments of traditional compression and TUV compression were carried out, the influence of vibration amplitude on yield strength, strain hardening coefficient and index, and strain rate hardening coefficient. The yield strength reduction is caused by the acoustic softening effect. The yield strength and strain hardening coefficient present a negative correlation with amplitude increase, the strain hardening index and strain rate hardening coefficient present a positive correlation with amplitude increase. Further, the accuracy of the developed constitutive model was quantitatively identified, the relative coefficient is as high as 0.954, the mean absolute percentage error less than 5.42%. On this basis, a user-defined subroutine was developed to implement the numerical simulation of the TUV forming processes using the finite element method, the results of numerical simulation and experiment are in good agreement, and prediction accuracy is as high as 95.25%. Therefore, the developed constitutive model can be well revealed the material deformation behavior and provides an application guide.

3

Application of two fracture models in impact simulations

Fras T., Roth C. C., Mohr D.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 2

317--325

EN

The following discussion concerns modelling of fracture in steel plates during an impact test, in which both target and striker are manufactured from the same material, high-strength high-hardness armour steel – Mars® 300. The test conditions (3 mm thick targets, projectiles with different nose shapes at impact velocity lower than 400 m/s) result in severely damaged components, which results in an analysis of stress states showing material failure. Numerical analyses are performed using two material models: the Johnson-Cook approach, as traditionally used in impact simulations, accounting for the effect of stress triaxiality, strain rate and temperature and for comparison, a simulation by means of the stress triaxiality and Lode angle parameter-dependent Hosford-Coulomb model, also incorporating the effect of the strain rate on a fracture initiation. The aim of the study is to analyse the mechanisms of penetration and perforation observed in the armour steel plates and validation of the modelling approaches.

4

Optimization of Johnson–Cook constitutive model parameters

Löschner Piotr, Jarosz Krzysztof, Niesłony Piotr

Journal of Machine Engineering

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2019

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Vol. 19, No. 3

66--73

EN

In modern machining industry, the concept of process optimization has gained widespread recognition. FEM simulations are commonly used for the optimization of machining operations, allowing for a proper choice of tool geometry and process parameters to obtain results that are in accordance with end user criteria. However, one has to be wary that a good agreement of experimental and simulation results is mandatory if the simulation is to be used as a basis for optimization of a real-life process. Therefore, a proper choice of constitutive model parameters is vital. Those parameter values are dependent on many variables. Constitutive model parameter values are determined experimentally – therefore, they are accurate only for the conditions (temperature, strain rate etc.) under which the experiment was performed. The alteration, or optimization of model parameters is necessary if cutting and experiment conditions differ, if one wishes to obtain applicable results. In this work, the authors aim to present a method of optimizing the Johnson–Cook constitutive model parameters to obtain a better fit with experimental data.

5

Study on constitutive model and deformation mechanism in high speed cutting Inconel718

Hao Zhao Peng, Li Ji Ning, Fan Yi Hang, Ji Fang Fang

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

439--452

EN

The nickel-based alloy Inconel718 is a multi-component complex alloy. There exists complex cutting deformation, higher cutting temperature, higher cutting force and formation of serrated chip in the machining process. However, the formation time of every saw tooth unit in serrated chip is very short. It is difficult to use traditional method to analyze the chip at any time. Simulation analysis, integrated with the experimental results, was used to study the whole process of cutting deformation. The Johnson–Cook (JC) constitutive model of Inconel718 under high speed and high strain rate is established through split Hopkinson pressure bar (SHPB) test. The finite element method was used to study the deformation process. Combining the analysis of metallographic pictures which were obtained in the cutting experiment, the plastic behavior evolution of material in the cutting zone is deeply studied to further reveal the forming mechanism of serrated chip. The results showed that the local temperature in the cutting zone increased rapidly. The appearance of thermal softening of materials led to the change of stress distribution in the cutting zone. The thermoplastic shear instability further appeared which resulted in the shear localization, subsequently leading to the uneven deformation of chip and then serrated chip formed.

6

Wpływ parametrów modelu konstytutywnego Johnsona-Cooka na wyniki symulacji numerycznych procesu skrawania

Löschner P., Jarosz K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2018

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z. 109

57--64

PL

W artykule zaprezentowano wpływ wartości parametrów modelu konstytutywnego Johnsona–Cooka na wyniki symulacji MES procesu toczenia. W symulacjach użyte zostały cztery dostępne w literaturze zestawy parametrów modelu J–C dla stopu tytanu Ti6Al4V. Wyniki symulacji zostały porównane pod kątem otrzymanych wartości siły skrawania, rozkładu naprężeń oraz postaci wióra. Odnotowano znaczący wpływ wartości parametrów modelu J–C na wyniki symulacji.

XX

The article presents the effect of different sets of Johnson–Cook constitutive model parameters on the results of an FEM turning process simulation. Four different sets of parameters available for Ti6Al4V titanium alloy taken from open literature were used. Simulation results were compared on the account of cutting force, stress distribution and chip shape. The research has shown a substantial effect of J–C model parameter values on simulation results.

7

Analiza za pomocą MES wpływu zużycia ostrza na temperaturę skrawania

Znojkiewicz N., Madajewski M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2017

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z. 89 [295], nr 4

573--583

PL

W artykule przedstawiono analizę metodą elementów skończonych wpływu stopnia zużycia powierzchni przyłożenia na temperaturę procesu, a także model formowania wióra. Symulację prowadzono dla modelu Johnsona-Cooka. Do analizy wybrano dwie płytki skrawające. Ostrza były zamodelowane jako bryły idealnie sztywne, dlatego nie definiowano dla nich opisu zachowania materiału w zakresie występowania odkształceń plastycznych. Badanie każdego z ostrzy zostało przeprowadzone dla stanów zużycia wynoszących VBB = 0,25 mm, VBB = 0,40 mm i dla przypadku nowego ostrza. Podczas symulacji ostrza zostały poddane operacji toczenia ortogonalnego. Przedmiot obrabiany jest definiowany jako warstwa wióra powierzchni nieobrobionej oraz powierzchni obrobionej. Wszystkie wartości temperatury zostały zapisane dla czasu symulacji t = 1,0 ms. W wyniku analizy zmierzono maksymalną wartość temperatury na przedmiocie obrabianym i na ostrzu. Dodatkowo, w analizie temperatury przyjęto arbitralne punkty referencyjne dla przedmiotu obrabianego i ostrza. Zamieszczono także wyniki symulacji dla zmiennej HFL, przedstawiającej gęstość strumienia ciepła i przedstawiono rozkłady pól temperatury.

EN

This paper presents the finite element analysis of the influence of tool wear on the process temperature and on chip formation model behavior. The simulation was conducted for the Johnson--Cook constitutive model. Two cutting inserts were selected for the analysis. In the FE simulation the tool was modeled as a perfectly rigid body, therefore the stress-strain analysis was excluded from its domain. The simulations were carried out for the tool with wear VBB = 0.25 mm, VBB = 0.40 mm and for a new insert geometry. In the simulation, inserts were subjected to an orthogonal turning. The workpiece is defined as a chip layer, as well as non-machined and machined surface. All temperature values were recorded for the simulation time t = 1.0 ms. The maximum temperature values on the workpiece and the tool were measured. In addition, arbitrary reference points for the workpiece and cutting edge were taken into account in the temperature analysis. The simulation results of variable heat flux (HFL) density distribution and the distribution of temperature fields are also presented.

8

Interpretacja modelu materiałowego na przykładzie równania Johnsona–Cooka

Bok A.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2015

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z. 105

23-24

EN

The term of material model was defined. Its mathematical notation and constitutive character were described on Johnson-Cook equation. Three aspects of model interpretation were distinguished as well as methods of getting material parameters were meant.

9

Study of FEM model for tension and compression test for aluminum alloys samples in order to set materiał data

Zduniak B., Morka A., Gieleta R.

Journal of KONES

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2010

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Vol. 17, No. 3

527-532

EN

The purpose of this paper is to conform an available material data for aluminum alloy material (P A11). This task was filled with the aid of computer modeling techniques, which are based on Finite Element Method (FEM), and our own experimental tests of quasistatic tension/compression material samples. For this kind of research FEM is most commonly used, but there are also other numerical methods that can be applied. The idea of FEM is the division of the given continuous area into a finite number of subareas (finite elements) connected with one another in nodal points and approximation of solution inside the finite elements using interpolation functions and function values in nodes. Numerical analysis was performed with the LS-Dyna commercial software. Reconstruction of conditions of experiment required application of implicit method of numerical integration in time, so called implicit solver. At this stage of work the aluminum alloy P A11 with respect to Johnson-Cook model was researched. A further work for fmding a good material data for WHA, U12A steel for other constitutive models will be performed. A good agreement of the numerical and experimental results is received. Other material data used in modeling, which were not determined by experiment, assumed according to literature sources.