scholarly journals Monotonic Tension-Torsion Experiments and FE Modeling on Notched Specimens Produced by SLM Technology from SS316L

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 33
Author(s):  
Michal Kořínek ◽  
Radim Halama ◽  
František Fojtík ◽  
Marek Pagáč ◽  
Jiří Krček ◽  
...  
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Numerical Study ◽  
Vertical Direction ◽  
Production Method ◽  
Image Correlation ◽  
Isotropic Hardening ◽  
Notched Specimens ◽  
Hill Criterion ◽  
3D Printed

The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the “as printed” state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the “as printed” state is also compared with 3D printed machined specimens and specimens produced by conventional methods. “As printed” specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of “as printed” specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed.

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller

2011 ◽  
Vol 32 (4) ◽  
pp. 351-366 ◽  
Author(s):  
Houari Ameur ◽  
Mohamed Bouzit ◽  
Mustapha Helmaoui
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Power Consumption ◽  
Yield Stress ◽  
Short Distance ◽  
Numerical Study ◽  
Stirred Vessel ◽  
Higher Power ◽  
Shear Thinning Fluid ◽  
Good Agreement

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller The present work deals with agitation of non-Newtonian fluids in a stirred vessel by Scaba impellers. A commercial CFD package (CFX 12.0) was used to solve the 3D hydrodynamics and to characterise at every point flow patterns especially in the region swept by the impeller. A shear thinning fluid with yield stress was modelled. The influence of agitator speed, impeller location and blade size on the fluid flow and power consumption was investigated. The results obtained are compared with available experimental data and a good agreement is observed. It was found that an increase in blade size is beneficial to enlargement of the well stirred region, but that results in an increased power consumption. A short distance between the impeller and the tank walls limits the flow around the agitator and yields higher power consumption. Thus, the precise middle of the tank is the most appropriate position for this kind of impeller.

scholarly journals Experimental and numerical study of the interaction between dynamically loaded cracks and pre-existing flaws in edge loaded PMMA specimens

2020 ◽  
Author(s):  
Chuzhali Nilath Irfan Habeeb ◽  
shmuel osovski
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Numerical Study ◽  
Damage Model ◽  
Image Correlation ◽  
High Speed Photography ◽  
Dynamic Fracture Tests ◽  
Micromechanical Damage ◽  
Fracture Tests ◽  
Micromechanical Damage Model

Dynamic fracture tests are carried out for four groups of hole-containing edge loaded specimens. The crack growth velocity, crack path, and dynamic toughness are extracted from the experiments using high-speed photography and digital image correlation. The importance of the interaction between the in-coming stress wave and the pre-existing hole is revealed and analyzed. A micromechanical damage model is calibrated to the experimental data from two of the specimens' designs and evaluated for its predictive capabilities using the other experimental configurations. The studied model is shown to be in reasonable agreement with the experimental data, and its limits are discussed

A nonlinear simulation of a bi-failure specimen through improved discretisation methods: A validation study

2018 ◽  
Vol 53 (8) ◽  
pp. 616-629 ◽  
Author(s):  
Behzad V Farahani ◽  
Jorge Belinha ◽  
Paulo J Tavares ◽  
Pedro MGP Moreira
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Numerical Study ◽  
Interpolation Method ◽  
Yield Criterion ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Nonlinear Simulation

A robust and efficient scheme is rendered to elastoplastically study the material nonlinearity of structural components. In this investigation, a specimen manufactured from the aluminium alloy AA6061-T6 is considered. It is mechanically loaded under a uniaxial tensile state and the experimental strain datum is analysed by three-dimensional digital image correlation. Due to specific specimen geometry, complex stress states will occur. However, the specimen yields due to an approximated uniaxial stress state. The obtained remote stress/strain from experimental data is used to validate the computational solutions using advanced discretisation approaches. Therefore, as a preliminary numerical study, the model is simulated through the finite element method formulation. Afterwards, another numerical strategy is adopted – the radial point interpolation method. The Newton–Raphson initial stiffness method is thereby adapted to complete the nonlinear solutions algorithm. Furthermore, the elastoplastic demeanour of aluminium alloys is determined with the von Mises yield criterion, an isotropic hardening rule and an associative flow rule. Obtained computational results fit the experimental digital image correlation solution, which allow to conclude that the proposed meshless methodology is efficient and reliable.

scholarly journals Equi-Biaxial Loading Effect on Austenitic Stainless Steel Fatigue Life

2015 ◽  
Author(s):  
S. Bradaï ◽  
C. Gourdin ◽  
S. Courtin ◽  
J. C. Le Roux ◽  
C. Gardin
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Numerical Study ◽  
Strain Tensor ◽  
Austenitic Stainless Steels ◽  
Nuclear Industry ◽  
Image Correlation ◽  
Biaxial Fatigue ◽  
The Impact

Fatigue lifetime assessment is essential in the design of structures. Under-estimated predictions may result in unnecessary in service inspections. Conversely, over-estimated predictions may have serious consequences on the integrity of structures. In some nuclear power plant components, the fatigue loading may be equi-biaxial because of thermal fatigue. So the potential impact of multiaxial loading on the fatigue life of components is a major concern. Meanwhile, few experimental data are available on austenitic stainless steels. It is essential to improve the fatigue assessment methodologies to take into account the potential equi-biaxial fatigue damage. Hence this requires obtaining experimental data on the considered material with a strain tensor in equi-biaxial tension. Two calibration tests (with strain gauges and image correlation) were used to obtain the relationship between the imposed deflection and the radial strain on the FABIME2 specimen. A numerical study has confirmed this relationship. Biaxial fatigue tests are carried out on two austenitic stainless steels for different values of the maximum deflection, and with a load ratio equal to −1. The interpretation of the experimental results requires the use of an appropriate definition of strain equivalent. In nuclear industry, two kinds of definition are used: von Mises and TRESCA strain equivalent. These results have permitted to estimate the impact of the equibiaxiality on the fatigue life of components.

scholarly journals A Novel Approach for a Faster Prototyping of Winter Sport Equipment Using Digital Image Correlation and 3D Printing

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 125
Author(s):  
Martino Colonna ◽  
Benno Zingerle ◽  
Maria Federica Parisi ◽  
Claudio Gioia ◽  
Alessandro Speranzoni ◽  
...  
Keyword(s):  
3D Printing ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Sport Activity ◽  
Image Correlation ◽  
Topological Optimization ◽  
Design Parameters ◽  
Sport Equipment ◽  
Novel Approach ◽  
3D Printed

The optimization of sport equipment parts requires considerable time and high costs due to the high complexity of the development process. For this reason, we have developed a novel approach to decrease the cost and time for the optimization of the design, which consists of producing a first prototype by 3D printing, applying the forces that normally acts during the sport activity using a test bench, and then measuring the local deformations using 3D digital image correlation (DIC). The design parameters are then modified by topological optimization and then DIC is performed again on the new 3D-printed modified part. The DIC analysis of 3D-printed parts has shown a good agreement with that of the injection-molded ones. The deformation measured with DIC are also well correlated with those provided by finite element method (FEM) analysis, and therefore DIC analysis proves to be a powerful tool to validate FEM models.

A simplified model of a multi-jointed mechanical finger calibrated with experimental data by vision system

2021 ◽  
Vol 235 (1) ◽  
pp. 164-175
Author(s):  
C Cosenza ◽  
V Niola ◽  
S Savino
Keyword(s):  
Experimental Data ◽  
Vision System ◽  
Control Strategies ◽  
Image Correlation ◽  
Robotic Hand ◽  
Prosthetic Device ◽  
Prosthetic Hands ◽  
Mechanical Hand ◽  
Free Mode ◽  
Mechanical Finger

The development of suitable models for mechanical fingers, whether they are part of prosthetic device or of a robotic hand, is a powerful tool to predict the behaviour of their components since the early stages of design, especially for underactuated mechanisms. Experimental data can improve the reliability of such models and promote their application to build proper control strategies especially for prosthetic hands. Here, we have developed a multi-jointed model of a mechanical finger. The finger is part of the Federica hand: an underactuated mechanical hand that was conceived for prosthetic purpose. The model accounts for friction phenomena in the finger and it is tuned with experimental data acquired through a digital image correlation device. The model allowed us to write kinematics relations of the phalanges and evaluate finger configurations in relation to the closure velocity. Moreover, it was possible to estimate the tendon force and the work analysis occurring during the closure tasks, both in free mode and in presence of objects.

scholarly journals Experimental demonstration of negative refraction with 3D locally resonant acoustic metafluids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benoit Tallon ◽  
Artem Kovalenko ◽  
Olivier Poncelet ◽  
Christophe Aristégui ◽  
Olivier Mondain-Monval ◽  
...  
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Multiple Scattering ◽  
Silicone Rubber ◽  
Acoustic Waves ◽  
Scattering Theory ◽  
Negative Refraction ◽  
Volume Fraction ◽  
Experimental Demonstration ◽  
Acoustic Beam

AbstractNegative refraction of acoustic waves is demonstrated through underwater experiments conducted at ultrasonic frequencies on a 3D locally resonant acoustic metafluid made of soft porous silicone-rubber micro-beads suspended in a yield-stress fluid. By measuring the refracted angle of the acoustic beam transmitted through this metafluid shaped as a prism, we determine the acoustic index to water according to Snell’s law. These experimental data are then compared with an excellent agreement to calculations performed in the framework of Multiple Scattering Theory showing that the emergence of negative refraction depends on the volume fraction $$\Phi$$ Φ of the resonant micro-beads. For diluted metafluid ($$\Phi =3\%$$ Φ = 3 % ), only positive refraction occurs whereas negative refraction is demonstrated over a broad frequency band with concentrated metafluid ($$\Phi =17\%$$ Φ = 17 % ).

scholarly journals Material parameter identification using finite elements with time-adaptive higher-order time integration and experimental full-field strain information

2021 ◽  
Author(s):  
Stefan Hartmann ◽  
Rose Rogin Gilbert
Keyword(s):  
Experimental Data ◽  
Finite Elements ◽  
Parameter Identification ◽  
Material Parameter ◽  
Measurement Data ◽  
Least Square ◽  
Image Correlation ◽  
Field Strain ◽  
Material Parameter Identification ◽  
Full Field

AbstractIn this article, we follow a thorough matrix presentation of material parameter identification using a least-square approach, where the model is given by non-linear finite elements, and the experimental data is provided by both force data as well as full-field strain measurement data based on digital image correlation. First, the rigorous concept of semi-discretization for the direct problem is chosen, where—in the first step—the spatial discretization yields a large system of differential-algebraic equation (DAE-system). This is solved using a time-adaptive, high-order, singly diagonally-implicit Runge–Kutta method. Second, to study the fully analytical versus fully numerical determination of the sensitivities, required in a gradient-based optimization scheme, the force determination using the Lagrange-multiplier method and the strain computation must be provided explicitly. The consideration of the strains is necessary to circumvent the influence of rigid body motions occurring in the experimental data. This is done by applying an external strain determination tool which is based on the nodal displacements of the finite element program. Third, we apply the concept of local identifiability on the entire parameter identification procedure and show its influence on the choice of the parameters of the rate-type constitutive model. As a test example, a finite strain viscoelasticity model and biaxial tensile tests applied to a rubber-like material are chosen.

Oscillatory Heat Transfer in a Pipe Subjected to a Laminar Reciprocating Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 592-597 ◽  
Author(s):  
T. S. Zhao ◽  
P. Cheng
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Nusselt Number ◽  
Numerical Study ◽  
Temperature Cycle ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Cycle Space ◽  
Reciprocating Flow

An experimental and numerical study has been carried out for laminar forced convection in a long pipe heated by uniform heat flux and subjected to a reciprocating flow of air. Transient fluid temperature variations in the two mixing chambers connected to both ends of the heated section were measured. These measurements were used as the thermal boundary conditions for the numerical simulation of the hydrodynamically and thermally developing reciprocating flow in the heated pipe. The coupled governing equations for time-dependent convective heat transfer in the fluid flow and conduction in the wall of the heated tube were solved numerically. The numerical results for time-resolved centerline fuid temperature, cycle-averaged wall temperature, and the space-cycle averaged Nusselt number are shown to be in good agreement with the experimental data. Based on the experimental data, a correlation equation is obtained for the cycle-space averaged Nusselt number in terms of appropriate dimensionless parameters for a laminar reciprocating flow of air in a long pipe with constant heat flux.

Sign in / Sign up

Export Citation Format

Share Document