An analysis of the superplastic forming of a thin circular diaphragm

Enikeev, F. U.; Kruglov, A. A.

doi:10.1016/0020-7403(94)00081-t

Cited by 94 publications

(71 citation statements)

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“…Numerical simulations were run implementing the two sets of material constants: one coming from the analytical model [19] and the other coming from the inverse analysis [20]. In Figure 10 numerical results have been compared in terms of thickness distributions along the longitudinal path of the formed component, being the equivalent time (t*) equal to 0.4 (i.e.…”

Section: Spf Numerical Resultsmentioning

confidence: 99%

“…Using data from free inflation tests (dome height as a function of the time), material constants (C and m) for defining the Backofen power law (ߪ = ‫)̇ߝܥ‬ could be evaluated in a strain condition very similar to the one in the real forming process. In particular, material constants to be implemented in the FE model were evaluated both analytically, using the approach proposed by Enikeev and Kruglov [19], and through an inverse analysis based on a genetic algorithm coupled to dome height data from jump pressure tests [20].…”

Section: Methodsmentioning

confidence: 99%

“…In order to correctly simulate the experimental clamping action by the blank holder, the periphery of the blank was pinned. Material superplastic behaviour was modelled according to the Backofen power law: in particular, material constants obtained analysing free-inflation tests data using both the analytical approach [19] and the inverse analysis [20] were implemented. Coulomb's friction law was implemented in all simulations, setting the Coefficient of Friction to the value of 0.1.…”

Section: Spf Modelmentioning

confidence: 99%

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Biomedical Titanium alloy prostheses manufacturing by means of Superplastic and Incremental Forming processes

et al. 2016

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Abstract. The present work collects some results of the three-years Research Program "BioForming", funded by the Italian Ministry of Education (MIUR) and aimed to investigate the possibility of using flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The prosthetic implants used as case studies were from the skull; in particular, two different Ti alloys and geometries were considered: one to be produced in Ti-Gr23 by SPF and one to be produced in Ti-Gr2 by SPIF. Numerical simulations implementing material behaviours evaluated by characterization tests were conducted in order to design both the manufacturing processes. Subsequently, experimental tests were carried out implementing numerical results in terms of: (i) gas pressure profile able to determine a constant (and optimal) strain rate during the SPF process; (ii) tool path able to avoid rupture during the SPIF process. Post forming characteristics of the prostheses in terms of thickness distributions were measured and compared to data from simulations for validation purposes. A good correlation between numerical and experimental thickness distributions has been obtained; in addition, the possibility of successfully adopting both the SPF and the SPIF processes for the manufacturing of prostheses has been demonstrated.

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Section: Spf Numerical Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Spf Modelmentioning

confidence: 99%

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Biomedical Titanium alloy prostheses manufacturing by means of Superplastic and Incremental Forming processes

et al. 2016

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“…Методика определения реологических характери-стик материала по результатам тестовых формовок листовой заготовки в цилиндрическую матрицу была впервые предложена в работе [11]. Коэффициенты K, m предлагается искать следующим образом:…”

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“…В работе [13] сравниваются результаты примене-ния методик, описанных в работах [11,12], при иссле-довании поведения сплава Ti-6Al-4V при температуре 1200 K. В работах [14,13] определялись характеристи-ки сплавов AZ31(МФ2-1) и Inconel 718. Коэффициент скоростной чувствительности определялся c помощью уравнения (4), а параметры K, n -с помощью обратного анализа.…”

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Application of inverse analysis for a determination of material rheological constants basing on forming tests of circular membranes

Юрьевич¹,

Алексеевич²,

Валентиновна³

2017

LoM

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The paper is devoted to a problem of determining rheological characteristics of materials from the results of experiments on free forming of sheet blanks to a cylindrical matrix. This information on the material behavior is used in the design of gas forming processes for the production of parts for aerospace industry. In computer simulations of the regimes for such technologies one should adequately describe the material properties. A disadvantage of the classical experimental method of tensile testing of plate specimens is that the information taken from these tests is related to metal forming in the conditions of uniaxial tension that is not typical for gas forming processes. Experimental method of forming circular membranes considered here allows one to study the behavior of a material in the conditions of biaxial tension. Interpretation of the results is proposed to carry out by an inverse analysis utilizing a special semianalytical model for the solution of the direct task. The key point of this semianalytical model is a dependence of the blank thickness at the dome pole on the dome height, which accounts for the strain rate sensitivity coefficient. This approach was applied for the processing of experimental results obtained by free forming of industrial aluminum alloys. Material characteristics obtained were compared to charecteristics determined by other methods for the same set of experimental data available in the literature. To estimate the efficiency of the method proposed, the characteristics obtained were verified by finite element simulations the results which were in good agreement with experimental data.Keywords: inverse analysis, mathematical simulation, free bulging, rheological characteristics, aluminum alloys.Применение обратного анализа для определения реологических констант материалов по результатам тестовых формовок круглых мембран Захарьев И.Ю. † , Аксенов С.А., Логашина И.В.Национальный исследовательский университет «Высшая школа экономики», ул. Мясницкая 20, 101000, Москва, Россия Работа посвящена проблеме определения реологических характеристик материалов по результатам тестовых фор-мовок листовой заготовки в цилиндрическую матрицу. Данная информация о материале используется при проек-тировании процессов газовой формовки изделий аэрокосмической отрасли. Реализация таких процессов требует соблюдения оптимальных технологических режимов, при расчетах которых необходимо адекватно описывать свой-ства материала, находящегося в состоянии пластического течения. Недостатком классической экспериментальной методики по растяжению плоских образцов является то, что полученная информация описывает формоизменение материала в условиях одноосного растяжения, нехарактерных для процессов газовой формовки. Рассматриваемая в работе экспериментальная методика по формовке круглых мембран позволяет исследовать поведение материа-ла в условиях двухосного растяжения. Интерпретацию результатов тестов предлагается осуществлять посредством обратного анализа с использованием при решении прямой задачи специальной пол...

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