scholarly journals Fiber Bragg Sensors Embedded in Cast Aluminum Parts: Axial Strain and Temperature Response

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1680
Author(s):  
Markus Lindner ◽  
Andrea Stadler ◽  
Georg Hamann ◽  
Bennet Fischer ◽  
Martin Jakobi ◽  
...  
Keyword(s):  
Tensile Test ◽  
Mechanical Load ◽  
Axial Strain ◽  
Temperature Response ◽  
Tensile Tests ◽  
Cast Aluminum ◽  
General Applicability ◽  
Cast Part ◽  
Different Types ◽  
Good Agreement

In this study, the response of fiber Bragg gratings (FBGs) embedded in cast aluminum parts under thermal and mechanical load were investigated. Several types of FBGs in different types of fibers were used in order to verify general applicability. To monitor a temperature-induced strain, an embedded regenerated FBG (RFBG) in a cast part was placed in a climatic chamber and heated up to 120∘C within several cycles. The results show good agreement with a theoretical model, which consists of a shrink-fit model and temperature-dependent material parameters. Several cast parts with different types of FBGs were machined into tensile test specimens and tensile tests were executed. For the tensile tests, a cyclic procedure was chosen, which allowed us to distinguish between the elastic and plastic deformation of the specimen. An analytical model, which described the elastic part of the tensile test, was introduced and showed good agreement with the measurements. Embedded FBGs - integrated during the casting process - showed under all mechanical and thermal load conditions no hysteresis, a reproducible sensor response, and a high reliable operation, which is very important to create metallic smart structures and packaged fiber optic sensors for harsh environments.

scholarly journals Constitutive Modeling of the Densification Behavior in Open-Porous Cellular Solids

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2731
Author(s):  
Ameya Rege
Keyword(s):  
Constitutive Model ◽  
Cell Walls ◽  
Compressive Strain ◽  
Pore Collapse ◽  
Compressive Response ◽  
Linear Elastic ◽  
Nonlinear Springs ◽  
Different Types ◽  
Point Of Intersection ◽  
Good Agreement

The macroscopic mechanical behavior of open-porous cellular materials is dictated by the geometric and material properties of their microscopic cell walls. The overall compressive response of such materials is divided into three regimes, namely, the linear elastic, plateau and densification. In this paper, a constitutive model is presented, which captures not only the linear elastic regime and the subsequent pore-collapse, but is also shown to be capable of capturing the hardening upon the densification of the network. Here, the network is considered to be made up of idealized square-shaped cells, whose cell walls undergo bending and buckling under compression. Depending on the choice of damage criterion, viz. elastic buckling or irreversible bending, the cell walls collapse. These collapsed cells are then assumed to behave as nonlinear springs, acting as a foundation to the elastic network of active open cells. To this end, the network is decomposed into an active network and a collapsed one. The compressive strain at the onset of densification is then shown to be quantified by the point of intersection of the two network stress-strain curves. A parameter sensitivity analysis is presented to demonstrate the range of different material characteristics that the model is capable of capturing. The proposed constitutive model is further validated against two different types of nanoporous materials and shows good agreement.

scholarly journals Calculating the optimal hematocrit under the constraint of constant cardiac power

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michal Sitina ◽  
Heiko Stark ◽  
Stefan Schuster
Keyword(s):  
Blood Flow ◽  
High Performance ◽  
Animal Species ◽  
Normal Values ◽  
Mechanical Load ◽  
The Body ◽  
Trade Off ◽  
Cardiac Power ◽  
Optimal Value ◽  
Good Agreement

AbstractIn humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3–0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

scholarly journals Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Unai Mayo ◽  
Nerea Isasti ◽  
José M. Rodríguez-Ibabe ◽  
Pello Uranga
Keyword(s):  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Correlation Technique ◽  
Strain Partitioning ◽  
High Angle ◽  
Electron Backscatter ◽  
Different Types ◽  
Final Deformation ◽  
Micro Alloyed Steel ◽  
Backscatter Diffraction

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

Immunological Determined Plasminogen Groups And Its Possible Biological Relevance

1981 ◽  
Author(s):  
V Sachs ◽  
R Dörner ◽  
E Szirmai
Keyword(s):  
Human Plasma ◽  
Type I ◽  
Type Ii ◽  
Precipitation Line ◽  
Gene Frequencies ◽  
Type Iii ◽  
Different Types ◽  
Human Plasminogen ◽  
Gel Diffusion ◽  
Good Agreement

Anti human plasminogen sera of the rabbit precipitate human plasma in the agar gel diffusion test by means of intra-basin absorption with plasminogenfree human plasma with three different types: type I is represented by one strong precipitation line, type II by two lines, a big one and a small one, and type III by three slight but distinct lines. The following frequencies of the different types have been observed in a sample of 516 human plasmas: type I 65%, type II 33% and type III 2%. Suppose the types are phenotypical groups of a diallelic system where the types I and III represent the homozygous genotypes and the type II the heterozygous the estimated gene frequencies are in good agreement with the expected values. There is also a good agreement of the distribution of plasminogen groups determined by electrofocussing from RAUM et al. and HOBART. The plasminogen groups possibly may have also a biological meaning because the plasmas of type III always have a lesser fibrinolytic activity than the plasmas of the other types.

Optimization of Cold-Formed Channel Sections Using Imperialist Competitive Algorithm

2012 ◽  
Vol 166-169 ◽  
pp. 493-496
Author(s):  
Roya Kohandel ◽  
Behzad Abdi ◽  
Poi Ngian Shek ◽  
M.Md. Tahir ◽  
Ahmad Beng Hong Kueh
Keyword(s):  
Sequential Quadratic Programming ◽  
Optimization Problems ◽  
Imperialist Competitive Algorithm ◽  
Computational Method ◽  
Compression Force ◽  
Sqp Method ◽  
Competitive Algorithm ◽  
Different Types ◽  
Formed Channel ◽  
Good Agreement

The Imperialist Competitive Algorithm (ICA) is a novel computational method based on the concept of socio-political motivated strategy, which is usually used to solve different types of optimization problems. This paper presents the optimization of cold-formed channel section subjected to axial compression force utilizing the ICA method. The results are then compared to the Genetic Algorithm (GA) and Sequential Quadratic Programming (SQP) algorithm for validation purpose. The results obtained from the ICA method is in good agreement with the GA and SQP method in terms of weight but slightly different in the geometry shape.

Predicting the surface waviness of sheet moulding compound parts by simulating process-induced thermal stresses

2011 ◽  
Vol 31 (8-9) ◽  
Author(s):  
Walter Michaeli ◽  
Christoph Kremer
Keyword(s):  
Thermal Stresses ◽  
Surface Defects ◽  
Computation Method ◽  
Surface Waviness ◽  
Curing Reaction ◽  
Calculated Stress ◽  
Moulding Compound ◽  
Different Types ◽  
Sheet Moulding Compound ◽  
Good Agreement

Abstract This paper describes an opportunity to compute the surface waviness of compression moulded sheet moulding compound (SMC) parts by simulating residual stresses. First, different types of surface defects occurring on SMC parts are discussed. A method for calculating the surface waviness of the compression moulded part is presented, which combines the simulation of the production process and the structural computation. Modelling of the curing reaction and the development of mechanical properties are discussed and implemented. The potential of the computation method is shown for an automotive fender made of SMC. The results state that the curing reaction of SMC can be well described using the approach of Ng and Manas-Zloczower. The position of the measured waviness on the examined fender is in good agreement with the calculated stress distribution.

scholarly journals Approaches to the Mechanical Properties of Threaded Studs Welded to RHS Columns

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1429
Author(s):  
Ismael García ◽  
Miguel A. Serrano ◽  
Carlos López-Colina ◽  
Fernando L. Gayarre ◽  
Jesús M. Suárez
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Efficient Solutions ◽  
Bolted Joints ◽  
Building Structures ◽  
Static Behavior ◽  
Steel Tubes ◽  
Punch Test ◽  
Different Types ◽  
The Face

The use of Rectangular Hollow Sections (RHS) as columns in steel construction includes important advantages like higher mechanical strength and fire resistance. However, the practical demountable bolted joints between beams and columns are not easy to execute, due to impossibility of access to the inner part of the tube. The use of threaded studs welded to the face of the tube and bolted to the beam by means of angle cleats is one of the cheaper and most efficient solutions to obtain beam–column joints with a semi-rigid behavior, as is usually sought in building structures. Nevertheless, it is important to point out that the stud-diameter and the stud-class selection may affect the mechanical properties of the welded parts of the joint. In this paper, 8MnSi7 (with a commercial designation K800) and 4.8 threaded studs were welded to RHS steel tubes and mechanical properties on the weld, the Heat Affected Zones (HAZ), and the base metal were obtained in two different ways: through a correlation with the Vickers hardness and by means of the Small Punch Test (SPT). A study of the microstructure and tensile tests on the threaded studs and in the columns was also carried out. The research involved different types of stud qualities, tube wall thicknesses, and stud diameters. The work presented in this paper proved that in most cases, the welded joint between these studs and the RHS steel tubes present a reasonable static behavior that fulfils the requirements for the beam–column joints under static loading.

Establishment of an ANSYS-Based Constitutive Modeling for Age Forming of Aluminum Alloy

2012 ◽  
Vol 217-219 ◽  
pp. 1497-1500 ◽  
Author(s):  
Xiao Jun Zuo ◽  
Jun Chu Li ◽  
Da Hai Liu ◽  
Long Fei Zeng
Keyword(s):  
Aluminum Alloy ◽  
Constitutive Equation ◽  
Material Model ◽  
Tensile Tests ◽  
Material Constants ◽  
Tensile Process ◽  
Simulation Based ◽  
Optimal Material ◽  
Two Stages ◽  
Good Agreement

Constructing accurate constitutive equation from the optimal material constants is the basis for finite element numerical simulation. To accurately describe the creep ageing behavior of 2A12 aluminum alloy, the present work is tentatively to construct an elastic-plastic constitutive model for simulation based on the ANSYS environment. A time hardening model including two stages of primary and steady-state is physically derived firstly, and then determined by electronic creep tensile tests. The material constants within the creep constitutive equations are obtained. Furthermore, to verify the feasibility of the material model, the ANSYS based numerical scheme is established to simulate the creep tensile process by using the proposed material model. Results show that the creep constitutive equation can better describe the deformation characteristics of materials, and the numerical simulations and experimental test points are in good agreement.

Deceleration of sliding motorcycles (mainly scooters) in accident reconstructions

2017 ◽  
Vol 232 (7) ◽  
pp. 866-876 ◽  
Author(s):  
Carlo Cialdai ◽  
Dario Vangi ◽  
Antonio Virga
Keyword(s):  
Urban Areas ◽  
Test Session ◽  
Road Accidents ◽  
Factors Affecting ◽  
Different Types ◽  
Energy Dissipated ◽  
Comparison Of The Results ◽  
Two Wheeler ◽  
The Impact ◽  
Good Agreement

This paper presents an analysis of the situation in which a two-wheeler (i.e. a motorcycle, where the term motorcycles includes scooters) falls over to the side and then successively slides; this typically occurs in road accidents involving this type of vehicle. Knowing the deceleration rate of the sliding phase allows the kinetic energy dissipated and the speed of the motorcycle just before the fall to the ground to be calculated. These parameters are very important in the analysis and reconstruction of accidents. The work presented in this paper was developed in two experimental test sessions on fully faired motorcycles which are mainly of the scooter type and widely used in urban areas. In the first session, sliding tests were carried out, with the speed in the range 10–50 km/h, on three different types of road surface. Analysis of the evidence allowed the dissipative main phases of motion of the motorcycle (the impact with the ground, the rebounds and the stabilized swiping) to be identified and some factors affecting the phenomenon to be studied. The coefficient of average deceleration was calculated using two typical equations. The second test session consisted of drag tests. In these tests, the motorcycle, which had previously laid on its side, was dragged for a few metres at a constant speed of about 20 km/h, while the drag force was measured. A comparison of the results obtained in these tests with those obtained in the sliding tests yielded very good agreement in the coefficients of deceleration.

scholarly journals Statistics of Simulated Storm Waves over Bathymetry

2021 ◽  
Vol 9 (7) ◽  
pp. 784
Author(s):  
Arnida Lailatul Latifah ◽  
Durra Handri ◽  
Ayu Shabrina ◽  
Henokh Hariyanto ◽  
E. van Groesen
Keyword(s):  
Water Waves ◽  
Open Water ◽  
Storm Events ◽  
Extreme Waves ◽  
Marine Structures ◽  
Wave Statistics ◽  
Storm Waves ◽  
Different Types ◽  
Run Up ◽  
Good Agreement

This paper shows simulations of high waves over different bathymetries to collect statistical information, particularly kurtosis and crest exceedance, that quantifies the occurrence of exceptionally extreme waves. This knowledge is especially pertinent for the design and operation of marine structures, safe ship trafficking, and mooring strategies for ships near the coast. Taking advantage of the flexibility to perform numerical simulations with HAWASSI software, with the aim of investigating the physical and statistical properties for these cases, this paper investigates the change in wave statistics related to changes in depth, breaking and differences between long- and short-crested waves. Three different types of bathymetry are considered: run-up to the coast with slope 1/20, waves over a shoal, and deep open-water waves. Simulations show good agreement in the examined cases compared with the available experimental data and simulations. Then predictive simulations for cases with a higher significant wave height illustrate the changes that may occur during storm events.

Sign in / Sign up

Export Citation Format

Share Document