Modeling and Identification of the Mechanical Properties of Achilles Tendon With Application in Health Monitoring

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Piotr Kohut ◽  
Krzysztof Holak ◽  
Rafal Obuchowicz ◽  
Martyna Ekiert ◽  
Andrzej Mlyniec ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Ex Vivo ◽  
Degradation Kinetics ◽  
Image Correlation ◽  
Coarse Grained ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Type I ◽  
Experimental Part ◽  
Kinetic Coefficients

In this study, we develop a modeling and experimental framework for multiscale identification of the biomechanical properties of the human Achilles tendon (AT). For this purpose, we extend our coarse-grained model of collagen fibrous materials with a chemomechanical model of collagen type I decomposition. High-temperature degradation of molecular chains of collagen in a water environment was simulated using a reactive molecular dynamics (MD) method. The results from MDs simulations allowed us to define the Arrhenius equation for collagen degradation kinetics and calculate the energy of activation together with the frequency factor. Kinetic coefficients obtained from a MD simulations were further used to provide better calibration of the a coarse grained (CG) model of collagen denaturation. For the experimental part of our framework, we performed a uniaxial tensile test of the human AT with additional use of digital image correlation (DIC) for ex vivo strain tracking. Using a different path of strain tracking, we were able to include the inhomogeneity of deformation and, therefore, regional variations in tissue stiffness. Our results, both in modeling and the experimental part of the study, are in line with already existing reports and thus provide an improved approach for multiscale biomechanical and chemomechanical studies of the human AT.

scholarly journals Effect of PWHT on the Microstructure and Mechanical Properties of Friction Stir Welded DP780 Steel

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1097
Author(s):  
Umer Masood Chaudry ◽  
Seung-Chang Han ◽  
Fathia Alkelae ◽  
Tea-Sung Jun
Keyword(s):  
Mechanical Properties ◽  
Annealing Temperature ◽  
Tensile Elongation ◽  
Image Correlation ◽  
Frictional Heat ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Dp780 Steel

In the present study, the effect of post-weld heat treatment (PWHT) on the microstructure and mechanical properties of friction stir welded (FSW) DP780 steel sheets was investigated. FSW was carried out at a constant tool rotation speed of 400 rpm and different welding speeds (200 mm/min and 400 min/min). A defect free weld was witnessed for both of the welding conditions. The mutual effect of severe plastic deformation and frictional heat generation by pin rotation during the FSW process resulted in grain refinement due to dynamic recrystallization in the stir zone (SZ) and thermo-mechanically affected zone (TMAZ). Lower tensile elongation and higher yield and ultimate tensile strengths were recorded for welded-samples as compared to the base material (BM) DP780 steel. The joints were subsequently annealed at various temperatures at 450–650 °C for 1 h. At higher annealing temperature, the work hardening rate of joints gradually decreased and subsequently failed in the softened heat-affected zone (HAZ) during the uniaxial tensile test. Reduction in yield strength and tensile strength was found in all PWHT conditions, though improvement in elongation was achieved by annealing at 550 °C. The digital image correlation analysis showed that an inhomogeneous strain distribution occurred in the FSWed samples, and the strain was particularly highly localized in the advancing side of interface zone. The nanoindentation measurements covering the FSWed joint were consistent with an increase of the annealing temperature. The various grains size in the BM, TMAZ, and SZ is the main factor monitoring the hardness distribution in these zones and the observed discrepancies in mechanical properties.

scholarly journals Coupled Thermomechanical Response Measurement of Deformation of Nickel-Based Superalloys Using Full-Field Digital Image Correlation and Infrared Thermography

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2163
Author(s):  
Krzysztof Żaba ◽  
Tomasz Trzepieciński ◽  
Sandra Puchlerska ◽  
Piotr Noga ◽  
Maciej Balcerzak
Keyword(s):  
Surface Temperature ◽  
Strain Rate ◽  
Rolling Direction ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Response Measurement ◽  
Sheet Rolling ◽  
Inconel Alloys ◽  
The Relationship

The paper is devoted to highlighting the potential application of the quantitative imaging technique through results associated with work hardening, strain rate and heat generated during elastic and plastic deformation. The aim of the research presented in this article is to determine the relationship between deformation in the uniaxial tensile test of samples made of 1-mm-thick nickel-based superalloys and their change in temperature during deformation. The relationship between yield stress and the Taylor–Quinney coefficient and their change with the strain rate were determined. The research material was 1-mm-thick sheets of three grades of Inconel alloys: 625 HX and 718. The Aramis (GOM GmbH, a company of the ZEISS Group) measurement system and high-sensitivity infrared thermal imaging camera were used for the tests. The uniaxial tensile tests were carried out at three different strain rates. A clear tendency to increase the sample temperature with an increase in the strain rate was observed. This conclusion applies to all materials and directions of sample cutting investigated with respect to the sheet-rolling direction. An almost linear correlation was found between the percent strain and the value of the maximum surface temperature of the specimens. The method used is helpful in assessing the extent of homogeneity of the strain and the material effort during its deformation based on the measurement of the surface temperature.

Experimental-Numerical Assessment of Vintage Pipe and Girth Weld With a Geometrically Complex Corrosion Feature

2018 ◽  
Author(s):  
Stijn Hertelé ◽  
Timothy Galle ◽  
Koen Van Minnebruggen ◽  
Wim De Waele ◽  
Otto Jan Huising
Keyword(s):  
Tensile Test ◽  
Surface Profile ◽  
Image Correlation ◽  
Tensile Failure ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Fe Model ◽  
Axial Tensile ◽  
Simplifying Assumptions ◽  
Girth Welds

Standard pipe corrosion assessments are based on simplifying assumptions with respect to corrosion geometry and focus on pressure based loading. Moreover, when corrosion patches traverse girth welds, validity criteria to their assessment become impractically vague. The integrity of girth welds is additionally influenced by axial stresses, which may act in combination with hoop stress resulting from pressure. In an attempt to address these issues, the authors conducted a detailed assessment on a significant, highly irregular corrosion patch traversing a 12″ natural gas pipeline girth weld. The investigation comprises a full scale uniaxial tensile test and supporting detailed finite element (FE) analyses. Hereby, the model mesh adopts detailed geometrical characteristics resulting from a surface profile scan obtained from stereoscopic digital image correlation. The numerical model is validated based on the uniaxial tensile test, in the sense that plastic collapse and highly complex strain distributions are successfully reproduced. Finally, the FE model is used to explore axial tensile failure in presence of internal pressure.

Effect of specimen orientation to the rolling direction on uniaxial tensile forming and failure limits

2020 ◽  
Vol 234 (13) ◽  
pp. 1598-1603
Author(s):  
Puja Ghosal ◽  
Surajit Kumar Paul
Keyword(s):  
Sheet Metal ◽  
Ferritic Steel ◽  
Dual Phase Steel ◽  
Rolling Direction ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Correlation Technique ◽  
Dual Phase ◽  
Planar Anisotropy

Alteration of forming and failure limits due to planar anisotropy of the sheet metal significantly affects the safe forming operation region and finally successfully manufacturing of a sheet metal formed component. This article presents the effect of planar anisotropy on uniaxial tensile properties, forming and failure limits of cold-rolled ferritic and dual-phase steels. In-situ three dimensional digital image correlation technique is used to measure the evolution of local strain components during uniaxial tensile test. For both the steels, necking limit is highest for the specimen at an orientation of 90° to rolling direction, while failure limit is highest for those specimen whose orientation is 45° to rolling direction for ferritic steel, and both 0° and 90° to rolling direction for dual-phase steel. Uniaxial tensile deformation path for ferritic steel holds lower slope than dual-phase steel as depicted in major versus minor strain plot.

MECHANICAL CHARACTERIZATION OF NOTCHED HOT ROLLED MULTI-PHASE STEEL

2017 ◽  
Vol 41 (1) ◽  
pp. 39-50
Author(s):  
Ke Niu ◽  
Abdolhamid Akbarzadeh ◽  
Zengtao Chen
Keyword(s):  
Crack Formation ◽  
Sheet Steel ◽  
Rolling Direction ◽  
Experimental Studies ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Correlation Technique ◽  
Stretch Flanging ◽  
Hot Rolled

This paper presents a series of experimental and numerical studies on Hot Rolled Stretch Flanging steels. This study focuses on four prototyped Hot-Rolled Stretch Flanging steels (HR780SF). Circular- notched sheet steel samples are used to induce different stress triaxiality levels in the rolling direction of sheet materials. Digital image correlation technique measures the local true strain during the deformation process of the notched samples in uniaxial tensile test. The microstructure of the notched samples is examined to evaluate the effect of geometrical features of circular notches on the microstructural evolution during the plastic deformation. Finally, the numerical results obtained via a finite element simulation are validated by the collected experimental data. Our experimental studies reveal the possibility of crack formation along the width of HR780SF steels during the mechanical load. The crack formation, which deteriorates the structural performance of hot rolled steels, can be avoided by the heat treatment of samples prior to the mechanical tests. In addition, it is found that the effect of notch geometry on the stress state is much more considerable at the notch edge than the notch center.

scholarly journals Poisson’s ratios of molded pulp materials by digital image correlation method and uniaxial tensile test

2020 ◽  
Vol 15 ◽  
pp. 155892502090827
Author(s):  
Guangjun Hua ◽  
Maoteng Yang ◽  
Weimin Fei ◽  
Fude Lu
Keyword(s):  
Poisson’S Ratio ◽  
Correlation Method ◽  
Image Correlation ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Corrugated Board ◽  
Bamboo Pulp ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

The mechanical properties of molded pulp materials are the basis of the structural optimum design of molded pulp products. Therefore, the correlations between Poisson’s ratio and fiber structure, molding process, and thickness were found for materials including wood pulp, bamboo pulp, sugarcane pulp, white mixed pulp, black mixed pulp, recycled corrugated board pulp, and recycled newspaper pulp by the uniaxial tensile test and digital image correlation method. The fiber structures of the selected molded pulp materials were investigated by scanning electron microscopy. The results revealed Poisson’s ratios of wood pulp, bamboo pulp, sugarcane pulp, white mixed pulp, black mixed pulp, recycled corrugated board pulp, and recycled newspaper pulp to be 0.169, 0.108, 0.202, 0.120, 0.166, 0.098, and 0.044, respectively. Microstructural investigation further revealed that Poisson’s ratios of molded pulp materials were related to the fiber structure and drying method. The pulp material dried outside mold under lower pressure and temperature had a smaller Poisson’s ratio, while that dried inside mold under higher pressure and temperature had a larger Poisson’s ratio. The layered phenomenon of the molded pulp materials was also found by scanning electron microscopy images: the outer layer was denser than the inner layer. These results can provide guidance for the numerical simulation analysis and optimal design of molded pulp products.

Effect of Ductile Damage Evolution in Sheet Metal Forming: Experimental and Numerical Investigations

2010 ◽  
Vol 446 ◽  
pp. 157-169 ◽  
Author(s):  
Fethi Abbassi ◽  
Olivier Pantalé ◽  
Sébastien Mistou ◽  
Ali Zghal ◽  
Roger Rakotomalala
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Constitutive Law ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Plastic Behavior ◽  
Marquardt Algorithm

The numerical simulation based on the Finite Element Method (FEM) is widely used in academic institutes and in the industry. It is a useful tool to predict many phenomena present in the classical manufacturing forming processes such as necking, fracture, springback, buckling and wrinkling. But, the results of such numerical model depend strongly on the parameters of the constitutive behavior model. In the first part of this work, we focus on the traditional identification of the constitutive law using oriented tensile tests (0°, 45°, and 90° with respect to the rolling direction). A Digital Image Correlation (DIC) method is used in order to measure the displacements on the surface of the specimen and to analyze the necking evolution and the instability along the shear band. Therefore, bulge tests involving a number of die shapes (circular and elliptic) were developed. In a second step, a mixed numerical–experimental method is used for the identification of the plastic behavior of the stainless steel metal sheet. The initial parameters of the inverse identification were extracted from a uniaxial tensile test. The optimization procedure uses a combination of a Monte-Carlo and a Levenberg-Marquardt algorithm. In the second part of this work, according to some results obtained by SEM (Scaning Electron Microscopy) of the crack zones on the tensile specimens, a Gurson Tvergaard Needleman (GTN) ductile model of damage has been selected for the numerical simulations. This model was introduced in order to give informations concerning crack initiations during hydroforming. At the end of the paper, experimental and numerical comparisons of sheet metal forming applications are presented and validate the proposed approach.

Hybrid Adhesive Bonded and Riveted Joints – Influence of Rivet Geometrical Layout on Strength of Joints / Połączenia Hybrydowe Klejowo-Nitowe - Wpływ Geometrii Rozmieszczenia Nitów Na Wytrzymałość Połączeń

2012 ◽  
Vol 57 (4) ◽  
pp. 1127-1135 ◽  
Author(s):  
T. Sadowski ◽  
E. Zarzeka-Raczkowska
Keyword(s):  
Experimental Research ◽  
Lap Joints ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Stress Concentrations ◽  
Hybrid Joint ◽  
Riveted Joints ◽  
Hybrid Joints ◽  
Deformation Processes

The hybrid adhesive bonded and riveted joints have wider and wider application in different branches of engineering: aerospace, mechanical, civil etc. The hybrid joints’ strength is 1.5 to 3 times higher than only adhesive bonded joints’ strength. The hybrid joints characterize higher reliability during long-term working. In this article we present the influence of rivets’ lay-out geometry on the hybrid adhesive bonded/riveted joints response to mechanical loading. Experimental research was carried using 3-D digital image correlation system ARAMIS. This system enables monitoring of the deformation processes of the hybrid joint specimen up to failure. We analysed the state of deformation of the adhesive bonded double-lap joints reinforced by different numbers of rivets. The hybrid joint specimens were subjected to the uniaxial tensile test. Moreover, the influence of geometry of individual number of rivets’ layout (rivets arranged in one or more rows) for hybrid joint strength was studied. Experimental research was completed and supported by the computer simulations of the whole deformation processes of metal layers (aluminum), adhesive layers and rivets. Numerical simulations were conducted with the ABAQUS programme. The analysis of stress concentrations in different parts of the hybrid joint and their behaviour up to failure were investigated. Finally, the analysis and the comparison of the obtained results confirmed the influence of rivets’ lay-out geometry not only on rivets joints but also on the hybrid adhesive bonded/riveted joints.

Macroscopic and Microscopic Non-Uniform Deformations of Polycrystalline Pure Copper during Uniaxial Tensile Test with High Stress Gradient

2019 ◽  
Vol 794 ◽  
pp. 246-252 ◽  
Author(s):  
Akito Taniguchi ◽  
Takatoshi Maeyama ◽  
Makoto Uchida ◽  
Yoshihisa Kaneko
Keyword(s):  
Strain Field ◽  
Pure Copper ◽  
Stress Gradient ◽  
High Stress ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Curvature Radius ◽  
Uniaxial Tensile Test ◽  
Strain Concentration ◽  
Uniform Deformation

Metallic materials usually have microscopically heterogeneous structures, such as polycrystalline structures, affecting macroscopic mechanical characteristics. Both macroscopic and microscopic non-uniform deformations of polycrystalline pure copper under a moderate stress gradient were investigated. In this study, macroscopic and microscopic non-uniform deformations under higher stress gradients are investigated. Uniaxial tensile tests using three-curve specimens with different curvatures and grain sizes were performed. In order to evaluate the heterogeneous strain field in the specimen surface, the development of the displacement field was measured using the digital image correlation method (DIC). The stress field was evaluated by coupling the DIC and finite-element methods. In smaller-grain specimens, a strong strain concentration was generated in the minimum cross-section area. Although a strong strain concentration was also confirmed in a larger-grain specimen, the strain field depended not only on the specimen shape but also on the microscopic heterogeneity. This microstructure-driven non-uniform deformation was also observed in the specimen with a larger curvature radius. These results indicated that the macroscopic non-uniform deformation should be estimated by the material parameter related to the microscopic heterogeneity.

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