A Dislocation based Constitutive Model for Warm Forming of Aluminum Sheet

The formability of aluminum sheet can be improved considerably by increasing the temperature.\ud At elevated temperatures, the mechanical response of the material becomes strain rate dependent.\ud To accurately simulate warm forming of aluminum sheet, a material model is required that\ud incorporates the temperature and strain rate dependency. In this paper, the dislocation based\ud Alflow hardening model is used. The model incorporates the influence of the temperature and\ud strain rate effect on the flow stress by means of the storage and dynamic recovery of dislocations.\ud It also includes the effects of solute level, particle fraction and grain size. Cylindrical cup deep\ud drawing simulations are presented using shell elements. The anisotropic behavior of the sheet is\ud described by using the Vegter yield locus. Experimental drawing test data is used to validate the\ud modeling approach, where the model parameters follow from tensile tests

Finite element simulation of aluminum sheet warm forming using alflow hardening model

In order to accurately model the plastic deformation of Aluminum sheet at elevated temperatures, a model is required that incorporate the temperature and strain rate dependency of the material. In this article, two physically based models are compared: Bergstr¨om and Alflow model. Although both models can be fit quite well to monotonic tensile tests of 5754-O alloy, large differences appear if strain rate jumps are applied. The Alflow model also represents the negative strain rate sensitivity behavior of Al-Mg alloys at temperatures below 125±C

Thermo-mechanical Forming of Al–Mg–Si Alloys: Modeling and Experiments

In an ongoing quest to realize lighter vehicles with improved fuel efficiency, deformation characteristics of the material AA 6016 is investigated. In the first part of this study, material behavior of Al–Mg–Si sheet alloy is investigated under different process (temperature and strain rate) and loading (uniaxial and biaxial) conditions experimentally. Later, warm cylindrical cup deep drawing experiments were performed to study the effect of various parameters on warm forming processes, such as the effect of punch velocity, holding time, temper and temperature on force-displacement response. The plastic anisotropy of the material which can be directly reflected by the earing behavior of the drawn cups has also been studied. Finite element simulations can be a powerful tool for the design of warm forming processes and tooling. Their accuracy will depend on the availability of material models that are capable of describing the influence of temperature and strain rate on the flow stresses. The physically based Nes model is used to describe the influence of temperature and strain rate and the Vegter yield criterion is used to describe the plastic anisotropy of the sheet. Experimental drawing test data are used to validate the modeling approaches

Effect of temperature on anisotropy in forming simulations of aluminum alloys

A combined experimental and numerical study of the effect of temperature on anisotropy in warm forming of AA 6016-T4 aluminum was performed. The anisotropy coefficients of the Vegter yield function were calculated from crystal plasticity models with an adequate combination of extra slip systems. Curve fitting was used to fit the anisotropy coefficients calculated at discrete temperatures. This temperature dependent constitutive model was successfully applied to the coupled thermo-mechanical analysis of deep drawing of aluminum sheet and results were compared with experiments

A Study For Efficiently Solving Optimisation Problems With An Increasing Number Of Design Variables

Coupling optimisation algorithms to Finite Element Methods (FEM) is a very promising way to achieve optimal metal forming processes. However, many optimisation algorithms exist and it is not clear which of these algorithms to use. This paper investigates the sensitivity of a Sequential Approximate Optimisation algorithm (SAO) proposed in [1-4] to an increasing number of design variables and compares it with two other algorithms: an Evolutionary Strategy (ES) and an Evolutionary version of the SAO (ESAO). In addition, it observes the influence of different Designs Of Experiments used with the SAO. It is concluded that the SAO is very capable and efficient and its combination with an ES is not beneficial. Moreover, the use of SAO with Fractional Factorial Design is the most efficient method, rather than Full Factorial Design as proposed in [1-4]

Drainage System of Tegalsari Polder for Handling Flood and Tide in Tegal City Indonesia

Although in 2019 the local government of Tegal city Indonesia had constructed a retention basin at drainage system of Siwatu, Tegal Barat, Tegal city with a catchment area of 226 ha, the areas around the system still experienced flood and inundation. This study belonged to a descriptive qualitative research aimed to evaluate the performances of Siwatu drainage system and Tegalsari retention basin. Data of the study included field data and technical data from institutions. Based on the 15-year rainfall data (2014 – 2018) from Pemali - Comal PSDA Office, Central Java Province, Indonesia, the statistical parameters of Cs: 0.0027, Ck: 1.904, Sd: 15.91, Cv: 0.144 were obtained and so Gumbel method distribution was applied in the study, the return period rainfall of 10 years was 138 mm, the flood discharge for Qr.10 years was 9.63 m3/sec., the addition of long storage was 8×2,50×500 m, and the combination of pump addition was of 1 m3/sec. with the long storage of 8×2.00×500 m. By implementing one of the alternative choices, either flood or inundation could be resolved