Background Pulmonary artery hypertension (PAH) is a complex disorder that can lead to right heart failure. The generation of caveolin-1 deficient mice (CAV-1−/−) has provided an alternative genetic model to study the mechanisms of pulmonary hypertension. However, the vascular adaptations in these mice have not been characterized. Objective To determine the histological and functional changes in the

Background Hemolysis in sickle cell disease (SCD) releases cell free hemoglobin, which scavenges nitric oxide (NO), leading to pulmonary vascular vasoconstriction, increased pulmonary vascular resistance (PVR), and the development of PH. However, PVR is only one component of right ventricular (RV) afterload. Whether sickled red blood cells increase the total RV afterload, including compliance and wave

Background: Since the mechanical behavior of pantographic metamaterials depends upon the properties of their microstructure, accurate descriptions of unit cells are needed. Objective: The present effort is motivated by this requirement to characterize the detailed deformation of unit cells formed of two orthogonal sets of 3 beams. Methods: Their deformations in a bias extension test were measured via

Background Calcification was recently found to be present in the majority of cerebral aneurysms, though how calcification and the presence or absence of co-localized lipid pools affect failure properties is still unknown. Objective The primary objective is to quantify the biomechanical effect of a macro-calcification with surrounding Near-Calcification Region (NCR) of varying mechanical properties

Background Using a thin-walled tube torsion test to characterize a material’s shear response is a well-known technique; however, the thin walled specimen tends to buckle before reaching large shear deformation and failure. An alternative technique is the surface stress method (Nadai 1950; Wu et al. J Test Eval 20:396–402, 1992), which derives a shear stress-strain curve from the torque-angular displacement

Background Multiaxial dynamic loadings occur in many industrial cases and multiaxial dynamic test development is thus a crucial issue. Objective To meet this challenge, a biaxial compression Hopkinson bar set-up is designed. Methods The set-up consists of a striker, an input bar, an internal output bar and a co-axial external output tube (surrounding the internal bar). The internal output bar measures

Background Mouse models of abdominal aortic aneurysm (AAA) and dissection have proven to be invaluable in the advancement of diagnostics and therapeutics by providing a platform to decipher response variables that are elusive in human populations. One such model involves systemic Angiotensin II (Ang-II) infusion into low density-lipoprotein receptor-deficient (LDLr−/−) mice leading to intramural thrombus

Background Hypertension drives myocardial remodeling, leading to changes in structure, composition and mechanical behavior, including residual stress, which are linked to heart disease progression in a gender-specific manner. Emerging therapies are also targeting constituent-specific pathological features. All previous studies, however, have characterized remodeling in the intact tissue, rather than

Background The quality of Digital Volume Correlation (DVC) full-field displacement measurements depends directly on the characteristics of the X-ray Computed Tomography (XCT) equipment, and scan procedures used to acquire the tomographic images. Objective We seek to experimentally study the effects of XCT equipment and tomographic scan procedures on the quality of these images for DVC analysis, and

Background: Subcritical crack growth can occur in a brittle material when the stress intensity factor is smaller than the fracture toughness if an oxidizing agent (such as water) is present at the crack tip. Objective: We present a novel bi-material beam specimen which can measure environmentally assisted crack growth rates. The specimen is “self-loaded” by residual stress and requires no external

Background The non-uniform distribution of atherosclerosis within the arterial system is widely attributed to variation in haemodynamic wall shear stress. It may also depend on variation in pressure-induced stresses and strains within the arterial wall; these have been less widely investigated, at least in part because of a lack of suitable techniques. Objectives Here we show that local arterial strain

Background The VDA 238–100 tight radius V-bend test can be used to efficiently characterize the bendability and fracture limits of sheet metals in severe plane strain bending. Material performance in plane strain bending is critical for the selection of advanced high strength steels for energy absorbing structural components. Objective The detection of failure based upon a reduction in the punch force

Background A significant amount of uniaxial tensile tests has been carried out using Gleeble systems to investigate the viscoplastic deformation of boron steel (22MnB5) under hot stamping conditions. However, due to heat loss through the end clamps, a temperature gradient in the reduced parallel section of dog-bone shaped specimens is inevitable. Objective In the work reported in this paper, the effect

Background The integral method of incremental hole-drilling is used extensively to determine the residual stress distribution in isotropic materials. When used with Tikhonov regularization, the method is robust and produces accurate results with minimal uncertainty. Alternatively, an optimal hole depth distribution can be found using the method of Zuccarello to improve the conditioning of the calibration

Background Shape memory alloys (SMAs) are phase transforming materials featuring strong thermomechanical couplings. Infrared thermography and heat source reconstruction (HSR) enable to track the calorific signature of deformation processes. Objective The objective was to characterize the transformation processes in a superelastic nickel-titanium SMA wire subjected to a force-controlled superelastic

Background There are a variety of approaches that can be employed for Hopkinson bar compression testing and there is no standard procedure. Objectives A Split-Hopkinson pressure bar (SHPB) testing technique is presented which has been specifically developed for the characterisation of hazardous materials such as radioactive metals. This new SHPB technique is validated and a comparison is made with

Background The radial design for strain gauge rosettes used for hole-drilling residual stress measurements was established over 50 years ago and has remained almost unchanged since then. The design was developed to promote strain sensitivity, but was made without regard for ability to identify interior stresses. Consequently, only near-surface residual stresses can be identified. Objective The aim

Background In vivo characterization of mitral valve dynamics relies on image analysis algorithms that accurately reconstruct valve morphology and motion from clinical images. The goal of such algorithms is to provide patient-specific descriptions of both competent and regurgitant mitral valves, which can be used as input to biomechanical analyses and provide insights into the pathophysiology of diseases

Background It has been difficult to improve the intramedullary nail technique because of the lack of consistency in the procedures used to evaluate the bone-implant stiffness. Objective The goal of this study was to develop a simple methodology for determining the stiffness of a bone implant that considers the physiological loads and bone orientation, and allows a finite element analysis and its validation

Background: It is commonly admitted that a dissection initiates with an intimal tear or at least a defect inside the arterial wall. Nevertheless, few studies investigated the initiation sequence due to the difficulty to monitor this process. Objective: The objective of this work was to observe and investigate the mechanisms leading an intimal tear to propagate into a dissection. Methods: A custom-made

Background Flow curves can easily be obtained by uniaxial tensile tests, but strains are then limited by diffuse necking. For many applications, the flow stress must be known above this limit. Objective The main objective of this paper is to obtain flow curves for material with low uniform elongation to relatively high strains compared to a uniaxial tensile test. Method A novel in-plane sheet bending

Digital volume correlation (DVC), the volumetric extension of the popular digital image correlation (DIC) technique, is a powerful experimental tool for measuring 3D volumetric full-field displacements and strains. Most current DVC algorithms can be categorized into either local or finite-element-based global methods. As with most experimental approaches, there are drawbacks with each of these methods

Background Impact experiments, routinely performed at the macroscale, have long been used to study mechanical properties of materials. Microscale high-velocity impact, relevant to applications such as ballistic drug delivery has remained largely unexplored at the level of a single impact event. Objective In this work, we study the mechanical behavior of polymer gels subjected to high-velocity microparticle

Background: Advancements in the Digitial Image Correlation (DIC) technique over the past decade have greatly improved spatial resolution. However, many processes, such as plastic deformation, have a temporal component spanning from fractions of a second to minutes that has not yet been addressed in detail, particularly for DIC conducted in-situ in the scanning electron microscope (SEM). Objective:

Background The mechanical stimulus (i.e., stress or stretch) for growth occurring in the pressure-overloaded left ventricle (LV) is not exactly known. Objective To address this issue, we investigate the correlation between local ventricular growth (indexed by local wall thickness) and the local acute changes in mechanical stimuli after aortic banding. Methods LV geometric data were extracted from 3D

Background Aortic dissection (AD) is a common pathology and challenging clinical problem. A better understanding of the biomechanical effects preceding its initiation is essential for predicting adverse events on a patient-specific basis. Moreover, the predictability of patient-specific biomechanics-based computational models is hampered by uncertainty about boundary conditions and material properties

Background The interfacial peeling strength of lithium-ion battery electrodes is a very important mechanical property that significantly affects the electrochemical performance of battery cells. Objective To characterize the interfacial peeling strength of an electrode, an analytical model based on the energy balance principle is established by considering the state of charge (SOC), the energy release

Background The inverse relationship between muscle stress and cross-sectional area in cardiac preparations has repeatedly been reported in intact twitching muscles. However, the critical muscle size at which diffusion-limited delivery of oxygen begins to compromise muscle stress development is smaller than what is predicted by a mathematical model of muscle oxygenation. Objective In a twitching muscle

Equation (12) in the original article [1] gives the strain from the measured voltage on a full bridge configuration of the four strain gages. The full-bridge is intended to measure tension-compression strain (type III full-bridge), the correct equation is therefore [2]

Background The use of layer jamming materials has promising applications in soft robotics and vibration control, where there is a need to have materials that can change their properties in situ. However, there is limited research on analytically modeling the plastic deformation response of layer jamming materials attributed to the level of cohesion between layers that controls the shear resistance

Background Current techniques for tracking the displacement and strain patterns within contracting cardiac specimens often require ‘invasive’ markers to be fixed on the sample, offer only modest spatial resolution, and are computationally inefficient. Objective We present a new technique for determining, without requiring the addition of markers, the dynamic displacement and strain distribution within

Background In spite of the worldwide recognition of the importance of testing blast effects on dummy humans, there is a lack of blast simulators that are capable of generating realistic blast conditions in the laboratory. Objective The objective of the present study was to design, construct and test a blast tube that is able to accurately reproduce loading histories of actual explosions in the laboratory

Background Interlamellar bonding in the arterial wall is often compromised by cardiovascular diseases. However, several recent nationwide and hospital-based studies have uniformly reported reduced risk of thoracic aortic dissection in patients with diabetes. As one of the primary structural constituents in the arterial wall, elastin plays an important role in providing its interlamellar structural

Background Biomechanical models predicting plaque rupture and device-tissue interactions rely on accurate material properties to produce reliable simulation results. However, there is a wide variation in the reported stiffness properties for advanced atherosclerotic lesions. Objective The purpose of this study was to characterise isolated calcified and non-calcified portions of ex vivo carotid atherosclerotic

Background Stainless Steel Dissimilar Metal Welds (SS DMW) between low-alloy steel 18MND5 and austenitic 316L stainless steel are critical junctions in the currently operating reactors because of their heterogeneous microstructure and mechanical properties. The presence of a narrow hard layer of carburized martensite and austenite in the ferritic-austenitic interface creates an important hardness gradient

Background: Incremental hole-drilling with the integral method has been extensively used in composite laminates but is sensitive to small measurement errors. Error sensitivity can be reduced by limiting the number of depth increments used in the calculation procedure. This approach is limited if a rapidly varying residual stress distribution exists since the calculated stress in each incremental depth

Background: The ring-pull test, where a ring of tissue is hooked via two pins and stretched, is a popular biomechanical test, especially for small arteries. Although convenient and reliable, the ring test produces inhomogeneous strain, making determination of material parameters non-trivial. Objective: To determine correction factors between ring-pull-estimated and true tissue properties. Methods:

Background: Structural response measurements are challenging in aerodynamic testing environments due to high-speed requirements, facility vibrations, and the desire for non-intrusive measurements. Objective: This study uses stereo digital image correlation (DIC) to investigate the response of a jointed beam under aerodynamic loading in a shock tube. Methods: The incident shock subjects the beam to

Background Digital Image Correlation (DIC) is a length scale independent surface pattern matching and tracking algorithm capable of providing full field deformation measurements. The confident registration of this pattern within the imaging system becomes key to the derived results. Practically, conventional speckling methods use non-reliable, non-repeatable patterning methodologies including spray

Background Elastic fibers are composed primarily of the protein elastin and they provide reversible elasticity to the large arteries. Degradation of elastic fibers is a common histopathology in aortic aneurysms. Pentagalloyl glucose (PGG) has been shown to bind elastin and stabilize elastic fibers in some in vitro studies and in vivo models of abdominal aortic aneurysms, however its effects on native

Background Images from scanning electron microscopes, transmission electron microscopes and atomic force microscopes have been widely used in digital image correlation methods to obtain accurate full-field deformation profiles of tested objects and investigate the object’s deformation mechanism. However, because of the raster-scanning imaging mode used in microscopic observation equipment, the images

Background About 10 years ago, super-high energy Charpy specimens at the National Institute of Standards and Technology were removed from inventory due to unacceptable variability in absorbed energy, leading to the advent of new methods and materials to reduce the variability and maintain the prescribed energy levels. Objective In this paper, we investigated the ductile-to-brittle transitional behavior

Background Investigating the mechanical properties of biological and biocompatible hydrogels is important in tissue engineering and biofabrication. Atomic force microscopy (AFM) and compression testing are routinely used to determine mechanical properties of tissue and tissue constructs. However, these techniques are slow and require mechanical contact with the sample, rendering in situ measurements

Background Little is known about the effect of water content on the mechanical properties of dual cross-linked hydrogels. Objective To quantify the changes in the mechanical response and equilibrium modulus in a PVA hydrogel as a function of the hydration level. Methods A dual cross-linked hydrogel was tested in tension to a stretch of 1.3 at two stretch rates and in a stress relaxation test. The equilibrium

Background: Cardiac remodeling underpinning progressive hypertensive heart disease alters the three-dimensional structure of the extracellular matrix, as well as the laminar organization of myocardial sheetlets. The effect of pharmacological intervention on microstructural remodeling is not known. Objective: To examine the changes in myocardial microstructure that occur as a result of hypertensive

Background: Surface topography of pile-up and sink-in is an issue of strain-hardening behavior around pyramidal and spherical indentations. The relationship between the surface profile and the activated dislocations is not clearly understood. Objective: This study combined electron channeling contrast imaging (ECCI), electron backscatter diffraction-based (EBSD) techniques and 3D laser microscopy to

Background: Identification of damage at an early stage is crucial for critical structural components. Objective: Creep induced micro-voids in heat treated polycrystalline pure copper are experimentally and numerically characterized. Methods: This is accomplished by the use of non-linear ultrasonic waves. Numerically, the study is carried out on an elastic material with randomly located micro-voids

Background: The design and analysis of protective systems requires a detailed understanding of, and the ability to accurately predict, the distribution of pressure loads acting on an obstacle following an explosive detonation. In particular, there is a pressing need for accurate characterisation of blast loads in the region very close to a detonation, where even small improvised devices can produce

Insufficient data are available to fully understand the effects of metal additive manufacturing (AM) defects for widespread adoption of the emerging technology. Characterization of failure processes of complex internal geometries and defects in metal AM can significantly enhance this understanding. We aim to demonstrate a complete experimental measurement process and failure analysis method to study

Background: MEMS-based nanomechanical testing has received much interests. However, it remains challenging to perform displacement- and force-controlled nanomechanical tests (e.g., stress relaxation and creep). Objective: We report a MEMS-based device for displacement- and force-controlled tensile testing of 1D nanomaterials using feedback control. Methods: The device consists of an electrostatic actuator

Background: The strength of materials under extreme dynamic loading conditions, such as in the case of shock wave loading, is assessed from their spallation characteristics. Under laboratory conditions, flyer plate impact, or sometimes laser-induced stress waves, is employed to instigate spall in a material. These methods are often combined with velocity interferometer system for any reflector (VISAR)

Background: Experimental modelling techniques are still rare for composite structures under complex thermal environments. Objective: In this paper, by taking a fibre-reinforced composite plate (FRCP) as an example, a lumped parameter model of the FRCP with temperature dependence is developed from an experimental perspective. Methods: Initially, a series of thermal vibration measurements are performed

The original version of this article has been corrected to include authors middle initials in the author list. The details given in this correction are correct.

BackgroundA shear constraint was very recently proposed by Abedini et al. (Int. J. Solids and Structures 151: 118–134 2018) to evaluate and calibrate advanced non-quadratic anisotropic yield criteria and to eliminate what they called non-physical numerical artifacts in those criteria. ObjectiveThis investigation points out that such a shear constraint is in fact unnecessary for plane-stress orthotropic

BackgroundExperimental, fully three-dimensional mechanical characterization of opaque materials with arbitrary geometries undergoing finite deformations is generally challenging. ObjectiveWe present a promising experimental method and processing pipeline for acquiring and processing full-field displacements and using them toward inverse characterization using the Virtual Fields Method (VFM), a combination

BackgroundUnderstanding the mechanical response of elastomers to applied deformation at different strain rates and temperatures is crucial in industrial design and manufacture; however, this response is often difficult to measure, especially at high strain rates (e.g. > 100 s− 1), and more predictive methods to obtain constitutive relationships are required. ObjectiveThe objective of the research described

Although the time-dependent deformation behaviors of microscale materials have been investigated through experiments with uniaxial loading conditions, the influence of the strain gradient has not been clearly clarified due to the lack of appropriate testing methods. In the current study, to investigate the stress relaxation behavior of microscale single-crystal copper (Cu) at room temperature, a quantitative

Background: Despite a wealth of literature on medical high-intensity focused ultrasound (HIFU), there are knowledge gaps related to therapeutic ultrasound in the presence of bone obstructions. In particular, the literature on detailed imaging of ultrasonic wave-scattering at bones to validate numerical models is still sparse. Objective: Experimentally investigate the ultrasonic energy deposition in

Background: Tricuspid valve chordae tendineae play a vital role in our cardiovascular system. They function as “parachute cords” to the tricuspid leaflets to prevent prolapse during systole. However, in contrast to the tricuspid annulus and leaflets, the tricuspid chordae tendineae have received little attention. Few previous studies have described their mechanics and their structure-function relationship