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Experimental determination of springback characteristics in a three-point bending test of the aluminium alloy sheet with aluminium cladding

Kut Stanisław, Pasowicz Grzegorz, Stachowicz Feliks

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 2

307--313

EN

The springback phenomenon that occurs during cold forming is the main problem that affects the dimensional accuracy of bent products. This article presents the results of the analysis of the springback phenomenon occurring during a three-point air bending of 0.5 mm, 0.8 mm, 1.0 mm and 2.0 mm thick AW-2024 aluminium alloy sheet, AW-1050A aluminium clad. For sheets with a thickness of 1.0 mm and 2.0 mm, the influence of heat treatment and natural ageing time of sheets on the value of the springback coefficient was also tested. The springback characteristics were determined by defining the dependence of the springback coefficient on the bending deflection of the band. The experimental results obtained indicate a linear dependence of the value of the springback coefficient on the relative deflection w/fg index (w – distance between supports, fg – deflection under load), both in the case of the influence of the sheet thickness and the ageing time of the sheets.

2

Crystal plasticity elastic-plastic rate-independent numerical analyses of pollycrystalline materials

Wójcik Marta, Skrzat Andrzej, Stachowicz Feliks, Spišák Emil

Advances in Mechanical and Materials Engineering

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2023

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Vol. 40, nr 1

63--78

EN

Macroscopic analyses of plastic forming processes give only the overall description of the problem without the consideration of mechanisms of plastic deformation and the microstructure evolution. For the consideration of these processes, numerical simulations within crystal plasticity include the change of texture, anisotropy, and strain hardening of the material are used. In this paper, a crystal plasticity rate-independent model proposed by Anand and Kothari is applied for numerical analyses of polycrystalline materials. The slip was considered as the main mechanism of the plastic deformation. Basic constitutive equations of crystal plasticity for large deformation theories are presented. The selected results of elastic-plastic problems obtained using both macro- and micro- scales software for the explicit and implicit integration are featured here. The heterogeneous distribution of strain and stress in different grains are obtained, which is associated with the various crystal orientation. The crystal plasticity modelling of materials subject to plastic deformation involves not only the information about the change of a material’s shape in a macro-scale, but also describes the phenomena occurring in material in a micro-scale.

PL

Analizy makroskopowe procesów przeróbki plastycznej prezentują jedynie ogólny zarys rozważanego problemu, bez uwzględnienia mechanizmów odkształcenia plastycznego oraz ewolucji mikrostruktury. W celu rozważania procesów przeróbki plastycznej stosowane są symulacje numeryczne w ramach teorii plastyczności kryształów uwzgledniające zmianę tekstury, anizotropię oraz umocnienie odkształceniowe. W artykule zaprezentowano zastosowanie modelu Ananda i Kothari w ramach teorii plastyczności kryształów niezależnej od prędkości odkształcenia do rozwiązywania analiz numerycznych dla materiałów polikrystalicznych. W badaniach uwzględniono poślizg dyslokacyjny jako główny mechanizm odkształcenia plastycznego. Zaprezentowano wybrane rezultaty dla problemów sprężysto-plastycznych uzyskane zarówno w skali makro, jak i mikro- dla całkowania typu explicit i implicit. Uzyskano niejednorodny rozkład naprężenia i odkształcenia w poszczególnych ziarnach, związany z różną orientacją kryształów. Modelowanie numeryczne zzastosowaniem teorii plastyczności kryształów dla materiałów poddanych plastycznemu odkształceniu dostarcza nie tylko informacje o zmianie kształtu materiału w skali makro, ale także opisuje zjawiska zachodzące w materiale w skali mikro-.

3

The Influence of Natural Aging of the AlCu4Mg1 Aluminum Sheet Alloy on the Constitutive Parameters of Selected Models of Flow Stress

Kut Stanisław, Pasowicz Grzegorz, Stachowicz Feliks

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 5

216--229

EN

This paper presents the results of experimental studies aimed at determining constitutive parameters for selected constitutive equations of flow stress as a function of the natural aging time of 2 mm thick AlCu4Mg1 (AW-2024) sheet. The knowledge of these constitutive parameters as a function of aging time is necessary to analyze and model the processes of forming sheet metal stampings after heat treatment during natural aging. The constitutive parameters in individual constitutive equations were determined on the basis of the approximation of the course of strain hardening curves. The courses of these curves for the tested natural aging times in the range of 0-120 minutes after heat treatment were made on the basis of uniaxial stretching tests of samples taken in the directions of 0, 45 and 90 degrees to the direction of sheet rolling. The values of constitutive parameters as a function of natural aging time were determined for four popular models of flow stress: Hollomon, Swift, Voce and El-Magd. Moreover, the relationship between the natural aging time and the value of the yield strength in the tested aging time range was determined, and the accuracy of the investigated constitutive equations for describing the course of the flow stress of the tested sheet material was assessed on the basis of the analysis of approximation errors.

4

Bending Moment and Cross-Section Deformation of a Box Profile

Kut Stanisław, Stachowicz Feliks

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 2

85--93

EN

In the process of plastic bending of thin-walled profiles, there is a significant deformation of the cross-section, which has a very significant impact on the course and effects of the shaping process construction products. In this paper, the experimental, analytical as well as numerical analyses of the box profile bending process enabled to establish the relationships determining the dependence of the cross-sectional form and bending moment on the bending curvature. The following paper discusses pure bending moment and the cross-sectional deformation of 21.5×21.5×1.8 mm and 25×25×2.5 mm square tubes made of the 6060 aluminium alloy. Satisfactory agreement of the experimental results and numerical calculations was obtained for the values of horizontal and vertical wall deflection, as well as for the experimental, calculated and numerical bending moment characteristics.

5

Influence of sewage sludge conditioning with use of biomass ash on its rheological characteristics

Wójcik Marta, Stachowicz Feliks

Archives of Environmental Protection

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2019

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Vol. 45, no. 1

92--102

EN

This study presents the rheological properties of sewage sludge after conditioning with the application of biomass ash. The impact of sewage sludge pre-treatment on its viscosity, flow curves and thixotropy was investigated. The increase of shear stress and the decrease of viscosity were observed with the increase of shear rate. Obtained results were compared with raw sewage sludge and the sludge after modification by means of polyelectrolyte in the dosage of 1.5 g‧(kg d.m.)-1. The findings proved that samples of raw and conditioned sewage sludge had thixotropic characteristics. The correlation between moisture content and capillary suction time reduction as well as selected rheological parameters were also determined. On the basis of the obtained results it was stated that the Ostwald de Vaele model best fits the experimental data.

PL

Artykuł przedstawia wyniki badań dotyczących wpływu kondycjonowania osadów ściekowych z użyciem popiołów ze spalania biomasy na ich charakterystykę reologiczną. Zbadano lepkość oraz właściwości tiksotropowe osadów po ich kondycjonowaniu. Odnotowano wzrost naprężeń stycznych wraz ze wzrostem prędkości ścinania. Uzyskane rezultaty porównano z wynikami badań dla surowego osadu, jak i dla osadu kondycjonowanego z użyciem polielektrolitu w dawce 1,5 g(kg s.m.)-1. Stwierdzono również, że próbki kondycjonowanych osadów ściekowych wykazują właściwości tiksotropowe. Wyznaczono również zależności pomiędzy uwodnieniem, czasem ssania kapilarnego oraz wybranymi parametrami reologicznymi osadów. Na podstawie uzyskanych rezultatów stwierdzono, że najlepsze dopasowanie wykazuje model Ostwalda de Vaele.

6

Unconventional Materials from Sewage Sludge with a Potential Application in a Road Construction

Wójcik Marta, Bąk Łukasz, Stachowicz Feliks

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 4

65--75

EN

Limited possibilities of agricultural utilization of sewage sludge results in the development of unconventional methods of its final management. Recently, recycling of sewage sludge in road construction is under examination. Literature review mentions that properly prepared sludge might replace other conventional materials which are commonly used in a construction sector. In this paper, the proposition of the use of sewage sludge in the production of unconventional material for a road construction is presented. In laboratory tests, dewatered sewage sludge with the moisture content at the level of 62%, glass powder and quartz sand were applied. For the obtained product, physical and chemical characteristics were examined. The compressive strength and the hardness were also measured. The results were compared with other materials which are also used in construction sector. The research confirmed the possibility to produce a material from different fractions of waste, which might indicate usefulness in civil engineering.