Analytical Model to Determine the Strength of Form-Fit Connection Joined by Die-Less Hydroforming

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Christian Weddeling ◽  
Soeren Gies ◽  
Nooman Ben Khalifa ◽  
A. Erman Tekkaya
Keyword(s):  
Analytical Model ◽  
Load Transfer ◽  
Dissimilar Materials ◽  
Experimental Investigations ◽  
Mean Deviation ◽  
Material Parameters ◽  
Load Transfer Mechanism ◽  
Fundamental Understanding ◽  
Increasing Demand ◽  
Tube Geometry

Modern lightweight concept structures are increasingly composed of several dissimilar materials. Due to the different material properties of the joining partners, conventional and widely used joining techniques often reach their technological limits when applied in the manufacturing of such multimaterial structures. This leads to an increasing demand for appropriate joining technologies, like joining by die-less hydroforming (DHF) for connecting tubular workpieces. The present work introduces an analytical model to determine the achievable strength of form-fit connections. This approach, taking into account the material parameters as well as the groove and tube geometry, is based on a membrane analysis assuming constant wall thicknesses. Besides a fundamental understanding of the load transfer mechanism, this analytic approach allows a reliable joining zone design. To validate the model, experimental investigations using aluminum specimens are performed. A mean deviation between the calculated and the measured joint strength of about 19% was found. This denotes a good suitability of the analytical approach for the design process of the joining zone.

Analytical Methodology for the Process and Joint Design of Form-Fit Joining by Die-Less Hydroforming

2014 ◽  
Author(s):  
C. Weddeling ◽  
S. Gies ◽  
N. Ben Khalifa ◽  
A. Erman Tekkaya
Keyword(s):  
Load Transfer ◽  
Dissimilar Materials ◽  
Experimental Investigations ◽  
Engineering Structures ◽  
Analytical Methodology ◽  
Fundamental Understanding ◽  
Bending Stresses ◽  
Connection Type ◽  
Increasing Demand ◽  
Tube Geometry

In modern lightweight concepts, for example in automotive engineering, structures are increasingly composed of several dissimilar materials. Due to the different material properties of the joining partners, conventional and widely used joining techniques often reach their technological limits when applied in the manufacturing of such multi-material structures. This leads to an increasing demand for appropriate joining technologies, like joining by die-less hydroforming (DHF) for connecting tubular workpieces. The present work introduces an analytical model to determine the achievable joint strength of this connection type. This approach, taking into account the material parameters as well as the groove and tube geometry, is based on a membrane analysis with constant wall thickness. Additionally, bending stresses and friction are considered locally. Besides a fundamental understanding of the load transfer mechanism, this analytic approach allows a reliable joining zone design. To validate the model, experimental investigations using aluminum specimens were performed.

scholarly journals Particle Shape Effect on Macroscopic Behaviour of Underground Structures: Numerical and Experimental Study

2015 ◽  
Vol 36 (3) ◽  
pp. 67-74 ◽  
Author(s):  
Krzysztof Szarf ◽  
Gael Combe ◽  
Pascal Villard
Keyword(s):  
Particle Shape ◽  
Load Transfer ◽  
Mechanical Performance ◽  
Flexible Structures ◽  
Discrete Element ◽  
Grain Structure ◽  
Experimental Investigations ◽  
Shape Effect ◽  
Underground Structures ◽  
Buried Pipe

Abstract The mechanical performance of underground flexible structures such as buried pipes or culverts made of plastics depend not only on the properties of the structure, but also on the material surrounding it. Flexible drains can deflect by 30% with the joints staying tight, or even invert. Large deformations of the structure are difficult to model in the framework of Finite Element Method, but straightforward in Discrete Element Methods. Moreover, Discrete Element approach is able to provide information about the grain-grain and grain-structure interactions at the microscale. This paper presents numerical and experimental investigations of flexible buried pipe behaviour with focus placed on load transfer above the buried structure. Numerical modeling was able to reproduce the experimental results. Load repartition was observed, being affected by a number of factors such as particle shape, pipe friction and pipe stiffness.

scholarly journals Influence of blade geometry on secondary flow development in a transonic centrifugal compressor

2018 ◽  
Vol 2 ◽  
pp. I1RSJ3 ◽  
Author(s):  
Moritz Mosdzien ◽  
Martin Enneking ◽  
Alexander Hehn ◽  
Daniel Grates ◽  
Peter Jeschke
Keyword(s):  
Secondary Flow ◽  
Centrifugal Compressor ◽  
Large Scale ◽  
Optimization Methods ◽  
Experimental Investigations ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Flow Development ◽  
Transonic Centrifugal Compressor ◽  
Increasing Demand

Due to the increasing demand for higher efficiencies of centrifugal compressors, numerical optimization methods are becoming more and more relevant in the design process. To identify the beneficial features of a numerical optimized compressor design, this paper analyses the influence of arbitrary blade surfaces on the loss generation in a transonic centrifugal compressor. The paper therefore focuses on an analysis of the secondary flow development within the impeller blade passages. To do this, steady simulations were performed on both a baseline and an optimized blade design. Two distinct design features of the optimized compressor stage were identified, which lead to a more homogenous impeller exit flow and thus to an increase in total-to-static efficiency of 1.76% points: the positive lean in the near-tip region and the positive blade curvature in the rear part of the optimized impeller. Furthermore, through extensive experimental investigations conducted on a large scale test rig it has been possible to prove the particular impeller outflow characteristics of the baseline compressor stage.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane and Mixed Mode Bending Under Seismic Load: Computational Approach

2007 ◽  
Author(s):  
Satoshi Tsunoi ◽  
Akira Mikami ◽  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Analytical Model ◽  
Failure Modes ◽  
Experimental Investigations ◽  
Seismic Load ◽  
Piping System ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Seismic Loadings ◽  
Local Wall Thinning

The authors have proposed an analytical model by which they can simulate the dynamic and failure behaviors of piping systems with local wall thinning against seismic loadings. In the previous paper [13], the authors have carried out a series of experimental investigations about dynamic and failure behaviors of the piping system with fully circumferential 50% wall thinning at an elbow or two elbows. In this paper these experiments have been simulated by using the above proposed analytical model and investigated to what extent they can catch the experimental behaviors by simulations.

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