Transverse Strain Research Articles

Axial Compression Performance and Bearing Capacity Calculation of Round-Ended Concrete-Filled Aluminum Tube Column

This study aimed to investigate the axial compression performance of concrete-filled circular-end aluminum tube (RECFAT) columns, utilizing four specimens with varying parameters such as cross-sectional aspect ratio and cross-sectional aluminum content. Axial compression tests and ABAQUS finite element extended parameter analyses were conducted, with key mechanical performance indicators such as specimen failure morphology, ultimate bearing capacity, load–displacement curve, and load–strain curve being obtained. The influence of various variation parameters on the axial compression performance of the specimen was analyzed. The results indicated that the majority of specimens underwent oblique shear failure due to local bulging of the aluminum tube plane, while specimens with an aspect ratio of 4.0 experienced overall instability failure. As the aspect ratio increased, the bearing capacity improvement coefficient and ductility coefficient of the specimen decreased and the initial stiffness of the specimen gradually decreased. As the aluminum content increased, the initial stiffness decreased, with the critical aspect ratio for overall instability being between 2.0 and 2.5. The optimal aluminum content was recommended to be between 8.5% and 13.5%. When the aspect ratio was around 2.0, the lateral strain of the round-ended aluminum tube developed faster and the constraint effect was the best. The finite element model accurately reproduced the oblique shear bulging of the round-ended aluminum tube and the internal concrete V-shaped collapse, with the axial load–displacement curve being in good agreement. Improving the strength of aluminum alloy was more conducive to improving the axial compression bearing capacity of RECFAT than increasing the strength of concrete. A simplified model and calculation method for RECFAT was proposed, with an error of less than 1%.

Tailoring the weld microstructure to prevent solidification cracking in remote laser welding of AA6005 aluminium alloys using adjustable ringmode beam

Solidification cracking is a prevalent defect in welding aluminium alloys which can be effectively mitigated by employing grain refinement strategies. This paper investigates the feasibility of tailoring the weld zone grain structure of 6xxx series aluminium alloys using an adjustable ring mode (ARM) laser beam to reduce the centreline cracking susceptibility. An in-process monitoring approach, comprising a high-speed camera and an ad-hoc Digital Image Correlation, was adopted to examine the strain development during laser welding on a self-restraint test rig. Results revealed that transverse strain in the weld centre exhibits a parabola-like relationship with the core/ring power ratio, with the minimum strain determined at the power ratio of ∼1.5, regardless of the total power employed. The microstructural analysis demonstrated that increasing the core/ring power ratio can lead to the refinement of columnar and equiaxed grains. Furthermore, the formation of secondary equiaxed grains is promoted when the power ratio increases, and this is proved to be related to the characteristic of the ARM laser by the like-for-like comparison. Overall, a fine-tuned power ratio of 1.5 is determined in the studied material and welding configuration for achieving a centreline crack free weld, benefiting from the improved microstructure and reduced thermal strain.

In Vivo Adaptive Bayesian Regularized Lagrangian Carotid Strain Imaging for Murine Carotid Arteries and Its Associations With Histological Findings

ObjectivesNon-invasive methods for monitoring arterial health and identifying early injury to optimize treatment for patients are desirable. The objective of this study was to demonstrate the use of an adaptive Bayesian regularized Lagrangian carotid strain imaging (ABR-LCSI) algorithm for monitoring of atherogenesis in a murine model and examine associations between the ultrasound strain measures and histology. MethodsUltrasound radiofrequency (RF) data were acquired from both the right and left common carotid artery (CCA) of 10 (5 male and 5 female) ApoE tm1Unc/J mice at 6, 16 and 24 wk. Lagrangian accumulated axial, lateral and shear strain images and three strain indices—maximum accumulated strain index (MASI), peak mean strain of full region of interest (ROI) index (PMSRI) and strain at peak axial displacement index (SPADI)—were estimated using the ABR-LCSI algorithm. Mice were euthanized (n = 2 at 6 and 16 wk, n = 6 at 24 wk) for histology examination. ResultsSex-specific differences in strain indices of mice at 6, 16 and 24 wk were observed. For male mice, axial PMSRI and SPADI changed significantly from 6 to 24 wk (mean axial PMSRI at 6 wk = 14.10 ± 5.33% and that at 24 wk = –3.03 ± 5.61%, p < 0.001). For female mice, lateral MASI increased significantly from 6 to 24 wk (mean lateral MASI at 6 wk = 10.26 ± 3.13% and that at 24 wk = 16.42 ± 7.15%, p = 0.048). Both cohorts exhibited strong associations with ex vivo histological findings (male mice: correlation between number of elastin fibers and axial PMSRI: rs = 0.83, p = 0.01; female mice: correlation between shear MASI and plaque score: rs = 0.77, p = 0.009). ConclusionThe results indicate that ABR-LCSI can be used to measure arterial wall strain in a murine model and that changes in strain are associated with changes in arterial wall structure and plaque formation.

Cavitation bubble induced wall shear stress on an elastic boundary

A cavitation bubble imposes shear stresses onto a nearby structure during its expansion and collapse. Experimentally, we probe the tangential stresses on an elastic surface by measuring the displacement of embedded particles and the deformation of an elastic structure. Corresponding numerical simulations are done using a fluid–structure interaction Volume-of-Fluid solver in OpenFOAM, where a linear elastic solid is coupled to two viscous, immiscible, and compressible fluids. We find good agreement in terms of bubble dynamics and displacement motions. During the initial bubble expansion and its first collapse, the experiment agrees with the simulation that the strain of the elastic sheet at a distance of 1.25 Rmax from the stagnation point center is larger than at 0.51 Rmax. The maximum lateral strain occurs at a non-dimensionalized bubble stand-off distance of γ≈1.1. The highest calculated wall shear stress is 250 kPa (for position y = 0). However, the largest overall shear stress of 1.9 MPa is found within the elastic sheet at y=24 μm that corresponds to a maximum displacement of Dx=44.5μm. Thus, fracture may start from within the elastic material rather than from the surface. To further examine the fluid–structure interaction, we construct a simple axisymmetrical elastic ring and analyze its deformation. In this case, we find strong deformations not only during the bubble collapse but also during the bubble's initial expansion.

Static and free vibration analysis of sandwich shells with double curvature considering the effects of transverse normal strain

Higher-order closed-form solutions for the static and free vibration problems of sandwich shells with double curvature are presented in the current study based on a new hyperbolic shell theory considering the effects of transverse normal strain. A theory involves six unknowns and satisfies traction-free boundary conditions at the top and the bottom surfaces of the shell. The theory does not require a shear correction factor to account for the strain energy due to the shear deformation effect. A shell consists of three layers, wherein the top and the bottom layers, i.e. face sheets are made up of hard material and the middle layer, i.e. core is made up of soft material. The governing equations and associated boundary conditions of the theory are produced by employing Hamilton’s principle. Semi-analytical closed-form solutions for the static and free vibration problems are produced by the Navier technique for simply supported boundary conditions of the shell. The present results are compared with results that have already been published to confirm the accuracy and efficacy of the current higher-order hyperbolic shell theory.

Effects of transverse normal strain on the deformation of laminated and sandwich arches under the action of concentrated force

It is well-known that the concentrated force develops high-stress concentration at the point of application which is one of the important parameters to be considered while designing the laminated composite structures under the action of concentrated force. The literature available shows that the study on static deformation of laminated sandwich shallow arches under the action of the concentrated force is limited. In the present study, static deformation of laminated sandwich arches under the action of concentrated loading is investigated using higher-order arch theory considering the effects of transverse normal strain. An exponential type higher-order arch theory is developed in this study which satisfies the traction-free boundary conditions at the top and the bottom surfaces of the arch using constitutive relations. Governing equations are derived within the framework of the principle of virtual work. An analytical solution for the static deformation of simply supported laminated and sandwich shallow arches are obtained using Navier’s technique. The effects of the lamination scheme, radius of curvature and aspect ratio on the deflection, and stresses of shallow arches are evaluated. The present results are compared with previously published results wherever possible for the verification of the present theory.

Topological phases in coupled polyyne chains

We study the electronic properties of coupled parallel polyyne chains in a couple of symmetric stacking arrangements, namely the AA stacking and the AB stacking, with the single and triple carbon bonds of one chain aligned (AA) and anti-aligned (AB) with those of the other chain. Both these arrangements described by tight-binding Hamiltonians, whose parameters are calibrated by matching low energy dispersion provided by first principle calculations, fall in the BDI class of topological classification scheme. We calculate the topological invariants for all three topological phases of the system: one for the AA stacking and 2 for the AB one. In AA stacking, both the insulating and the metallic phase belongs to the same topological phase. Whereas, the model exhibits two different values of the topological invariant in the two different insulating phases (structurally differentiated by transverse strain). In this later stacking though the transition between two distinct topological phases with the closure of the gap is practically unachievable due to the requirement of the high transverse strain. We also show the existence of four non-zero energy edge modes in the AA stacking and that of two zero energy edge modes in one of the topological phases for the AB stacking.

Nonlinear 2D-DQ volume-preservative global–local dynamic analysis of composite sandwich plates with soft hyperelastic cores and viscoelastic Winkler-Pasternak foundations

Nonlinear large amplitude vibration and dynamic deformations of sandwich plates with composite face sheets and hyperelastic cores that encounter large thickness changes during the vibration are investigated here for the first time. Moreover, a new global–local zigzag hyperelastic plate theory that considers the incompressibility and large transverse deformability of the core, and employs transverse normal strains whose order is higher than that of the in-plane strains is proposed. The plate is resting on a viscoelastic Winkler-Pasternak substrate, exposed to various spatial and time distributions of loads, and experiencing a diversity of edge conditions. The governing equations of motion are obtained by using Hamilton’s principle, von Kármán’s assumptions, and the series expansion of the volume-preserving strain energy density function. A 2D differential quadrature (2D-DQ) technique is employed for the spatial discretization of a structure with both constitutive and kinematic nonlinearities, for the first time. The time-dependent combination of the nonlinear coupled motion equations and boundary conditions is treated by an iterative/updating Runge-Kutta time-marching technique and the effects of the thickness and aspect ratio of the plate, viscoelastic and shear parameters of the foundation, types of the edge conditions, constitutive parameters of the composite materials, fiber orientation angle, and magnitude and distribution pattern of the loads on the resulting dynamic lateral deflections are studied. Results reveal that while the vibration frequencies and amplitudes of the face sheets are quite different, the damping is more remarkable when stiffer cores are utilized. Moreover, the effects of the higher vibration modes are more apparent in looser edge conditions, smaller fiber angles, and special excitation frequencies.

Compressive behavior of seawater coral concrete with varying confinement subjected to axial loading

Coral reef debris have emerged as a promising alternative to conventional natural coarse aggregates, driven by the increasing demand for oceanic structures. To comprehend the compressive behavior of coral aggregate concrete (CAC) with varying confinements which induced by the lateral dilation of concrete, further studies were required. To this end, a total of 81 specimens were preaperd encompassing three concrete grades (C20, C30 and C40). Among these, 9 speicmens without outer confinements, while 36 specimens confined by carbon fiber reinforced polymer (CFRP) and 36 specimens composited with 6061-T6 aluminium alloy tubes (AA). Furthermore, various parameters were explored to investigate their influence on the compressive behavior, including four layers of CFRP wraps (1, 2, 3 and 4) and four thickness of AA tubes (2 mm, 3 mm, 5 mm and 7 mm). Subsequently, an analysis was conducted to examine the effects of different parameters. By utilizing the Weibull damage distribution method, a damage constitutive model was developed to account for variations in confinement. Based on the simplified failure criterion of CAC, bearing models were developed. The findings indicate that both peak stress and peak strain increase with greater external confinement, and an increase in axial and lateral strain was also observed. Moreover, specimens confined with CFRP exhibited elastic behavior in their lateral stress, whereas specimens confined with AA displayed elasto-plasticity behavior. Finally, the varying lateral stress models presented accurate confinement predictions. The proposed damage-constitutive and bearing models showed good agreement with the measured results.

Synthesis and Evaluation of Engineering Properties of Polymer-Coated Glass Beads.

Modern construction projects are often challenging, which has increased the demand for innovative materials that ensure improved safety, durability, and functionality. To explore the potential of enhancing soil material functionality, this study synthesized polyurethane on the surface of glass beads and evaluated their mechanical properties. The synthesis of polymer proceeded according to a predetermined procedure, where the polymerization was confirmed through analysis of chemical structure by Fourier transform infrared spectroscopy (FT-IR) and microstructure observation by a scanning electron microscope (SEM) after complete synthesis. The constrained modulus (M) and the maximum shear modulus (Gmax) of mixtures with synthesized materials were examined by using an oedometer cell equipped with bender elements under a zero lateral strain condition. Both M and Gmax decreased with an increase in the contents of polymerized particles due to a decrease in the number of interparticle contacts and contact stiffness induced by the surface modification. The adhesion property of the polymer induced a stress-dependent change in M but was observed to have little effect on Gmax. Compared to the behavior of the rubber-sand mixtures, polymerized particles show the advantage of a smaller reduction of M.

Left atrial hyper-strain in dyssynchronous hearts: potential driver for adverse left atrial remodelling

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Institute for Surgical Research, Oslo University Hospital. Introduction It was recently shown that left bundle branch block (LBBB) is associated with risk of developing atrial fibrillation. A potential mechanism is abnormal left atrial (LA) loading caused by LA dyssynchrony. Purpose To investigate if LBBB is associated with abnormal LA loading as reflected in non-uniform segmental strains. Methods In a prospective study of 143 heart failure patients with LBBB, myocardial strain was measured by speckle-tracking echocardiography prior to and after 7±2 months on cardiac resynchronization therapy (CRT). As indicated by brackets in the lower panels in the Figure, LA strain amplitudes were calculated as the difference between minimum and peak strain during the reservoir phase. Results In the Figure, the upper panel shows segmental and average LA strain traces in a representative LBBB patient. This patient illustrates marked spatial non-uniformity in strain amplitude between the interatrial septum and the LA lateral wall during the reservoir phase. For the entire study population, strain amplitudes were 19±9% (mean±SD) for the interatrial septum and 24±11% for the LA lateral wall (p&amp;lt;0.0001). In the quartile of patients with largest differences, strain amplitudes were 16±9 and 32±12%, respectively (p&amp;lt;0.0001). CRT abolished these differences (p = NS). Conclusions Patients with LBBB showed marked spatial non-uniformity of LA strains. Potentially, the excessive LA lateral wall strain amplitudes may stimulate atrial adverse remodelling. Future studies should investigate if abnormal LA strains may be a trigger mechanism for atrial fibrillation in patients with LBBB.

A general leading-order asymptotic theory of thin microstructural plates and uncertainty quantification of the elastic performance of composite laminates

We propose an asymptotic framework that may be used as a platform to model general thin microstructural plates, and our initiative is twofold. First, it provides an explanation to why so many tailored plate theories have been introduced for modelling plates bearing microstructures. In hypotheses-based plate theories, the microstructural details within each ply are usually smeared out. But it is shown that with such in-ply details properly taken into account, one manages to address, even only with leading-order terms, several key issues, such as transverse shear strain effects, shear locking, etc., whose rationalisation is believed to necessitate higher-order terms. To a certain degree, the proposed formulation can be used as a target for tailoring kinematic shape functions in both Reissner-Mindlin types of plate theories and zig-zag theories. Second, being slender in nature, a microstructural plate should accommodate a stress state that is close to the state of plane stress. This agrees with our findings that the (leading-order) mechanical units of a microstructural plate should be two-dimensional slices parameterised with the thickness coordinate, distinguishing the proposed framework from other plate theories based on asymptotic analysis. To demonstrate what the present framework can predict beyond existing theories, the effects on the behaviour of fibrous laminates due to manufacturing uncertainties are investigated.

Dynamic responses of radiation-induced heavyweight concrete subjected to biaxial compression

As a good shielding material, heavyweight concrete is largely utilized for building the Concrete Biological Shielding (CBS) wall of the commercial nuclear power plant, and is often subjected to the biaxial loadings with a strain rate possibly varying from 10−5s−1 to 10−2s−1. This paper assesses the combined effects of the lateral stress and the strain rate on the compressive strength of radiation-induced heavyweight concrete on the example of serpentine concrete. For this goal, a 3-dimensional rectangular numerical concrete specimen containing special aggregates and ITZs was firstly established. Exposed to neutrons of different fluences, the initial damages caused by the fast neutron were assessed by a thermal-mechanical approach. Then, a series of static and dynamic biaxial compressive tests on the rectangular specimens having initial damages of different degrees were carried out by finite element analysis via ABAQUS. The failure modes, the crack patterns, and the ultimate compressive strengths of the pre-irradiated serpentine concrete were obtained numerically. Finally, based on the numerical results and the classical "Kupfer-Gerstle" ("K-G") criterion, this paper derives the biaxial strength criterion of the radiation-induced heavyweight concrete undergoing both lateral stress and strain rate. Through the formula, it was found that the fast neutron fluence of high level reduces significantly the biaxial compressive strength of the heavyweight concrete. Besides, if the heavyweight concrete undergoes additionally lateral stress and the strain rate, the biaxial compressive strength could be enhanced. The enhancement effect was maximized at the lateral stress ratio of 0.5 and the strain rate of 10−2s−1. The current numerical approach was developed with a potential application to the lifetime extension of the heavyweight concrete infrastructures used in commercial nuclear reactors.

Buckling analysis of plates using an efficient sinusoidal shear deformation theory

Mechanical buckling response of isotropic and orthotropic plates using the two variable refined plate theory is presented in this paper. The theory takes account of transverse shear effects and parabolic distribution of the transverse shear strains through the thickness of the plate; hence it is unnecessary to use shear correction factors. Governing equations are derived from the principle of virtual displacements. The nonlinear strain-displacement of Von Karman relations are also taken into consideration. The closed-form solution of a simply supported rectangular plate subjected to in-plane loading has been obtained by using the Navier method. Numerical results are presented for the present efficient sinusoidal shear deformation theory, demonstrating its importance and accuracy in comparison to other theories.

Load-bearing characteristics of 3D auxetic structures made with carbon fiber reinforced polymer composite

This paper presents a study of 3D novel hybrid auxetic structures made with carbon fiber reinforced polymer (CFRP) laminate composite based on the stretch-dominated mechanism. The homogenized mechanical characteristics of the designed structures, including Young's modulus, shear modulus, and Poisson's ratio, are evaluated via theoretical analysis and finite element simulation. The results exhibit that the structures have negative Poisson's ratio values in all the selected ranges of the design geometry parameters. The multi-objective optimization method is employed to achieve the optimized geometry parameters based on maximizing the stiffness and minimizing the relative density responses. Meanwhile, 2D fabricated auxetic sheets are assembled to build 3D structures through the interlocking method, and quasi-static compressive tests are performed to study their mechanical behaviors. The axial and lateral strains are evaluated by the strain gauge and video extensometer to measure the negative Poisson's ratio values through compressive tests. The results indicate that the proposed structures exhibit superior stiffness and high elongation percentage, suggesting them as a strong candidate for the next generation of load-bearing auxetic structures.

Formed developables - a new class of sheet metal parts

Sheet metal parts are broadly classified as stamped parts versus folded developables. While stamped parts are parts manufactured using conventional sheet metal forming techniques, folded developables are curved developable connections produced by the virtue of the classical theory of folded developables. However, folding is not suitable for parts where material integrity cannot be compromised at the fold lines. In such cases, forming techniques can be used to introduce a distributed curvature and avoid material self-intersection at the curved fold axis. This paper combines the two genres to introduce a third class of parts called the formed developables. A developable shaped, thin sheet metal of very high strength and reasonable inextensibility is formed by flange drawing over a die radius. The die tool establishes the required curved bend axis, and the die radius is small enough to introduce a distributed curvature. A developable connection is successfully formed where the two connected corrugations are mirror images of each other. While no tearing or wrinkling is observed, experimental strain measurements highlight significant surface strains in the transverse direction while marginal stretching strains are observed in the forming direction. A trend of equal and opposite transverse strains strongly suggests that the major deformation in this geometrical process, and in-turn the shape of the final part, is driven by the involved geometrical parameters.

Differentiation of strains in the lateral and medial bands of the iliofemoral ligament: A segmental approach.

Iliofemoral ligament strains have been assessed in a circumscribed portion, limiting the information regarding the strains in the proximal, mid and distal portions. The purpose of this study is to describe the longitudinal and transversal strain within the proximal, mid and distal portions of the lateral and medial bands of the iliofemoral ligament. Ten fresh cadaveric specimens were assessed. The iliofemoral ligaments were divided into medial and lateral bands. Hemispherical beads (2.6 mm) were placed on the lateral and medial borders of each band. Four positions were assessed: abduction, extension, internal and external rotations combined with extension. The hemispherical beads were scanned at the end range of motion using a laser scanner. The three-dimensional position of each bead was used to estimate longitudinal and transversal strains. A three-factor ANOVA was used to compare movements, borders, and portions within each ligament for longitudinal strains. A one-way ANOVA was used to compare transversal strains between portions. This technique showed mean reliability (ICC: 2, 1) of 0.90 ± 0.06. The external rotation showed the highest strains in both ligaments (p < 0.05). Abduction showed a significant difference between the lateral and medial borders in both bands (p = 0.001). Eight movement-border combinations showed a significant difference between proximal, medial, and lateral portions (p < 0.005). According to our results, there is a clear effect of portions (proximal, mid and distal) within the ligament and movements. Abduction shows the lowest strains longitudinally but the largest strains transversally. Although we do not know the impact of this phenomenon, future studies should assess the strains following hip arthroscopies. The latter might improve the impact of this procedure on hip biomechanics. Lastly, the iliofemoral ligament should be assessed using a segmental approach rather than as a complete unit.

Estimation of lateral stress of stirrups at peak stress and residual stress of confined concrete at stirrups fractured in confined concrete under axial compression

The lateral stress of stirrups at the peak stress of confined concrete was closely related to the load-bearing capacity and deformability of concrete columns, while the fracture of stirrups affected the axial deformability of concrete columns after the peak stress of confined concrete. In this paper, 156 circular concrete columns confined with spiral stirrups and 141 square concrete columns confined with mesh stirrups were tested under axial compression. The effects of the compressive strength of unconfined concrete, the volumetric ratio and the yield strength of stirrups on the lateral stress of stirrups at peak stress and the residual stress of confined concrete at stirrups fractured were analyzed. Furthermore, the prediction models for evaluating the lateral strain of stirrups at the peak stress of confined concrete were established by considering the effects of the volumetric ratio and type of stirrups and the compressive strength of concrete, which had high prediction performance. In addition, the method for judging whether stirrups fractured or not was developed, which was suitable for evaluating the stirrups with and without yield platform. The prediction model for evaluating the residual stress of confined concrete at stirrups fractured was proposed.

Experimental study of longitudinal, transverse and volume strains of magnetoactive elastomeric cylinders in uniform magnetic fields

Magnetoactive elastomers (MAEs) are promising materials for realization of magnetic field-controlled soft actuators. Herein, a systematic investigation of magnetic field-induced macroscopic deformations of soft MAE cylinders with a diameter of 15 mm in uniform quasi-static magnetic fields directed parallel to the cylinder’s axis is reported. The measurements were based on image processing. Thirty-six MAE samples differing in the weight fraction of the iron filler (70 wt%, 75 wt% and 80 wt%), alignment of filling particles, and the aspect ratio (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2) were fabricated. MAE cylinders exhibited high relative change in height (up to 35% in the field of 485 kA/m) and lateral contraction. The dependence of the maximum extensional strain on the aspect ratio was obtained and compared with theoretical considerations. A concave dent was formed on the free circular base in magnetic fields. This concavity was characterized experimentally. A significant volumetric strain of the order of magnitude of 10% was calculated in MAEs for the first time. In consequently repeated magnetization cycles, the remanent extensional strain significantly increased after each cycle. The results are qualitatively discussed in the framework of the modern views on the magnetically induced macroscopic deformations of MAEs. The directions of further research are outlined.

Analytical relationships for 2D Re-entrant auxetic metamaterials: An application to 3D printing flexible implants

Both 2D and 3D re-entrant designs are among the well-known prevalent auxetic structures exhibiting negative Poisson's ratio. The present study introduces novel analytical relationships for 2D re-entrant hexagonal honeycombs for both negative and positive ranges of the cell interior angle θ (θ<0 showing a negative Poisson's ratio). The derived analytical solutions are validated against finite element method (FEM) and experimental results. The results show that, compared to the analytical solutions available in the literature, the analytical relationships presented in this study provide the most accurate results for elastic modulus, Poisson's ratio, and yield stress. The analytical/computational tools are then implemented for designing Kinesio taping (KT) structures applicable to treatment of Achilles tendon injuries. One of the main features of the Achilles tendon is a natural auxetic behavior. Poisson's ratio distribution of an Achilles tendon is obtained using longitudinal and transverse strains and are then used to design and 3D print thermoplastic polyurethane (TPU) KT structures with non-uniform distribution of auxetic unit cells. The presented novel KT shows that it is capable of replicating the deformation and global and local Poisson's ratio distributions, similar to those of the Achilles tendon. Due to the absence of similar formulations and procedures in the literature, the results are expected to be instrumental for designing and 3D printing of flexible implants with unusual auxeticity.