scholarly journals Design and Analysis of a Bulge Test Device

2021 ◽  
Vol 41 (3) ◽  
pp. e85756
Author(s):  
Luis Humberto Martínez Palmeth ◽  
María Angelica Gonzalez Carmona ◽  
José Miranda Castro

The aim of this work is to present the methodological process to design a device capable of performing Bulge tests. This kind of device allows obtaining more information about the plastic behavior of a material than the one provided by a traditional tensile test. The engineering specifications of the device were evaluated through the QFD methodology. Then, a basic design of the device was performed based on available analytical models such as thick-walled pressure vessel theory, annular plate theory, and a basic plasticity model for the biaxial stress state. Later, a detailed design of the device was proposed, which was evaluated by means of a 3D model of finite elements and a linearstatic analysis for the main components. Finally, a 2D axisymmetric model and a dynamic non-linear analysis were performed to validate the proposed design. The main novelty of the work consists of articulating the methodology of the mechanical design process and the conception, design, and validation of a Bulge device while solving the deficiencies found in the literature regarding the design and validation processes of this type of devices.

2006 ◽  
Vol 129 (3) ◽  
pp. 414-421 ◽  
Author(s):  
Yeong-Maw Hwang ◽  
Yi-Kai Lin

This paper aims to evaluate the stress-strain characteristics of tubular materials considering their anisotropic effects by hydraulic bulge tests and a proposed analytical model. In this analytical model, Hill’s orthogonal anisotropic theory was adopted for deriving the effective stresses and effective strains under a biaxial stress state. Annealed AA6011 aluminum tubes and SUS409 stainless-steel tubes were used for the bulge test. The tube thickness at the pole, bulge height, and the internal forming pressure were measured simultaneously during the bulge test. The effective stress-effective strain relations could be determined by those measured values and this proposed analytical model. The flow stress curves of the tubular materials obtained by this approach were compared with those obtained by the tensile test with consideration of the anisotropic effect. The finite element method was also adopted to conduct the simulations of hydraulic bulge forming with the flow stress curves obtained by the bulge tests and tensile tests. The analytical forming pressures versus bulge heights were compared with the experimental results to validate the approach proposed in this paper.


2013 ◽  
Vol 549 ◽  
pp. 389-396 ◽  
Author(s):  
Harald Friebe ◽  
Markus Klein ◽  
Ingo Heinle ◽  
Arnulf Lipp

Axisymmetric die and binder are typically used in the bulge test, where the test specimen is formed by increasing the level of oil pressure (Fig. 1). With this experimental setup a biaxial stress state is induced at the specimen dome, assuming that it is not influenced by friction. The increasing oil pressure in the region of the top of the dome is recorded and the deformation field measured during the forming process. The optical measurement system determines the coordinates, the deformations and the curvature on the outer surface. Based on the forthcoming ISO 16808 these results are directly used for the calculation of the flow curve. In order to determine the flow curve based on the bulge test, an analytical approach is needed for the computation of the stress state at the top of the dome.


Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5076
Author(s):  
Javier Martinez-Roman ◽  
Ruben Puche-Panadero ◽  
Angel Sapena-Bano ◽  
Carla Terron-Santiago ◽  
Jordi Burriel-Valencia ◽  
...  

Induction machines (IMs) are one of the main sources of mechanical power in many industrial processes, especially squirrel cage IMs (SCIMs), due to their robustness and reliability. Their sudden stoppage due to undetected faults may cause costly production breakdowns. One of the most frequent types of faults are cage faults (bar and end ring segment breakages), especially in motors that directly drive high-inertia loads (such as fans), in motors with frequent starts and stops, and in case of poorly manufactured cage windings. A continuous monitoring of IMs is needed to reduce this risk, integrated in plant-wide condition based maintenance (CBM) systems. Diverse diagnostic techniques have been proposed in the technical literature, either data-based, detecting fault-characteristic perturbations in the data collected from the IM, and model-based, observing the differences between the data collected from the actual IM and from its digital twin model. In both cases, fast and accurate IM models are needed to develop and optimize the fault diagnosis techniques. On the one hand, the finite elements approach can provide highly accurate models, but its computational cost and processing requirements are very high to be used in on-line fault diagnostic systems. On the other hand, analytical models can be much faster, but they can be very complex in case of highly asymmetrical machines, such as IMs with multiple cage faults. In this work, a new method is proposed for the analytical modelling of IMs with asymmetrical cage windings using a tensor based approach, which greatly reduces this complexity by applying routine tensor algebra to obtain the parameters of the faulty IM model from the healthy one. This winding tensor approach is explained theoretically and validated with the diagnosis of a commercial IM with multiple cage faults.


2020 ◽  
pp. 1-18
Author(s):  
Elena Zarova ◽  
Dr Konstantin Laykam ◽  
Elvira Dubravskaya ◽  
Sergey Musikhin

This article describes on the one hand statistical methods for assessing informal employment based on the requirements as set by international standards. On the other hand it describes the potential of integrating various data sources to generate informal employment statistics. With as example official statistics of the Russian Federation, the authors show the features of applying the requirements of international standards. Methods are proposed for assessing informal employment in the formal sector of the economy, i.e. in enterprises that submit employment reports to the National Statistical Office. This phenomenon appears in the employment situation of many countries. However, there is no uniformity between countries in how they evaluate the application of the international standards in such assessment exercises. A theoretical model of informal employment is developed and validated based on statistical data published by international organizations. The validation focuses on assessing the causal relationships between informal employment indicators and the main components of the sustainable development goals. This analysis contributes to coordinated decisions on regulating informal employment and ensuring the achievement of the Sustainable Development Goals (SDGs).


Robotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 60
Author(s):  
Christoph Martin ◽  
Marc Fabritius ◽  
Johannes T. Stoll ◽  
Andreas Pott

Accuracy improvement is an important research topic in the field of cable-driven parallel robots (*CDPRS). One reason for inaccuracies of *CDPRS are deviations in the cable lengths. Such deviations can be caused by the elongation of the cable due to its elasticity or creep behavior. For most common *CDPRS, the cable lengths are controlled using motor encoders of the winches, without feedback about the actual elongation of the cables. To address this problem, this paper proposes a direct cable length measurement sensor based on a laser distance sensor. We present the mechanical design, the first prototype and an experimental evaluation. As a result, the measurement principle works well and the accuracy of the measured cable lengths is within −2.32 mm to +1.86 mm compared to a range from −5.19 mm to +6.02 mm of the cable length set with the motor encoders. The standard deviation of the cable length error of the direct cable length measurement sensor is 58% lower compared to the one set with the motor encoders. Equipping all cables of the cable robot with direct cable length measurement sensors results in the possibility to correct cable length deviations and thus increase the accuracy of *CDPRS. Furthermore, it enables new possibilities like the automatic recalibration of the home pose.


Author(s):  
Eren Billur ◽  
Muammer Koc¸

Hydraulic bulge testing is a material characterization method used as an alternative to tensile testing with the premise of accurately representing the material behavior to higher strain levels (∼70% as appeared to ∼30% in tensile test) in a biaxial stress mode. However, there are some major assumptions (such as continuous hemispherical bulge shape, thinnest point at apex) in hydraulic bulge analyses that lead to uncertainties in the resulting flow stress curves. In this paper, the effect of these assumptions on the accuracy and reliability of flow stress curves is investigated. The goal of this study is to determine the most accurate method for analyzing the data obtained from the bulge testing when continuous and in-line thickness measurement techniques are not available. Specifically, in this study the stress-strain relationships of two different materials (SS201 and Al5754) are obtained based on hydraulic bulge test data using various analysis methods for bulge radius and thickness predictions (e.g., Hill’s, Chakrabarty’s, Panknin’s theories, etc.). The flow stress curves are calculated using pressure and dome height measurements and compared to the actual 3-D strain measurement from a stereo optical and non-contact measurement system ARAMIS. In addition, the flow stress curves obtained from stepwise experiments are compared with the ones from above methods. Our findings indicate that Enikeev’s approach for thickness prediction and Panknin’s approach for bulge radius calculation result in the best agreement with both stepwise experiment results and 3D optical measurement results.


Author(s):  
Tetiana Vlasova ◽  
◽  
Olha Vlasova ◽  
Larysa Martseniuk

Among the diverse methodological approaches that are currently represented in the postmodern studies, the one, which dominates nowadays, is the statement that there cannot be any methodology in postmodernism per se otherwise it would be a “relapse” into constructing one more “universalizing method”. Evidently, this assertion is stipulated by the highly pluralized context of the postmodern “normalization of change”, the transformations of the socio- cultural order in accordance with the postparadigmatic shift of the theory. Postmodern researchers both implicitly and explicitly state that the only way to “manage” the increasing pluralism and diversity is unmasking prior modernist ideas and ideals in the individual and general meanings of the human experience. On the other hand, the postmodern methodological “openness” encourages academic ambivalence, which results in the denial of the universal notions and absolute moral values. With the apparent postmodernist accent on the interdisciplinary approaches, the “scientific conditions” have become even more complicated: nowadays philosophy, history, theology, gender studies, arts are being connected with biology, genetics, cybernetics, economics, etc. As one of the main components of the postmodern intertextual analysis the historical method is vividly represented both in the western feminist theory and in the eastern post-colonial criticism, poetics of fiction and cultural studies. All mentioned above, appearing in the pluralized modes, occasion the turn into considering interdisciplinary techniques more scrupulously. The objective of this research is to reconstruct conceptually the comparative-historical methodology in the theoretical field of the postmodern humanities with the focus on the specific character of the interpretation of history in the cultural texts. The main thesis of the research reflects the reconstruction of the historical methods as an important systematic and meaning-conscious component in postmodern theoretical studies. The research proves that nowadays historical approaches are significant and valid because they locate certain techniques into the contemporary scholarly work in order to properly utilize the sources and pieces of evidence in writing “history”. The value of the comparative-historical method is also based on the fact that it proposes some models and patterns in dealing with the analysis of the particular theory in interdisciplinary studies. The historical narrative with its objective to tell the “truth” cannot be reflected according to some simple schemes, without taking into account the “hardcore” role of the context in the hermeneutic reading of history. Though there is a view that historiography is located “between” modernity and postmodernity, the articulated point of view is that postmodernism, being a theoretical cluster of historical disruption and “brokenness”, in fact, cannot reject the tradition of historicism in the humanitarian studies.


2020 ◽  
Vol 12 (4) ◽  
pp. 1606 ◽  
Author(s):  
Vincenzo Barrile ◽  
Antonino Fotia ◽  
Giovanni Leonardi ◽  
Raffaele Pucinotti

Structural Health Monitoring (SHM) allows us to have information about the structure under investigation and thus to create analytical models for the assessment of its state or structural behavior. Exceeded a predetermined danger threshold, the possibility of an early warning would allow us, on the one hand, to suspend risky activities and, on the other, to reduce maintenance costs. The system proposed in this paper represents an integration of multiple traditional systems that integrate data of a different nature (used in the preventive phase to define the various behavior scenarios on the structural model), and then reworking them through machine learning techniques, in order to obtain values to compare with limit thresholds. The risk level depends on several variables, specifically, the paper wants to evaluate the possibility of predicting the structure behavior monitoring only displacement data, transmitted through an experimental transmission control unit. In order to monitor and to make our cities more “sustainable”, the paper describes some tests on road infrastructure, in this contest through the combination of geomatics techniques and soft computing.


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