Background Fused filament fabrication (FFF) introduces anisotropic material properties to the final parts, which includes minimum interlayer values. In this study, ASTM D638 type I specimens are 3D printed from acrylonitrile butadiene styrene (ABS) in the upright build direction and their tensile properties are evaluated. Objective Higher nozzle temperature outside the narrow section is proposed to

Background Digital image correlation (DIC) methods are increasingly used for non-contact optical assessment of geometry and deformation in soft tissue biomechanics, thus providing the full-field strain estimates needed for robust inverse material characterization. Despite the well-known flexibility and ease of use of DIC, issues related to spatial resolution and depth-of-field remain challenging in

Background The trend in miniaturisation of structural components and continuous development of more advanced crystal plasticity models point towards the need for understanding cyclic properties of engineering materials at the microscale. Though the technology of focused ion beam milling enables the preparation of micron-sized samples for mechanical testing using nanoindenters, much of the focus has

Background Hydrogen energy has received increased attention because of environmental needs and because it is an attractive replacement for fossil fuels. However, the presence of hydrogen in steels is known to be prejudicial to their global performance due to reduced ductility and unpredictable failures. Objective To understand the diffusivity of hydrogen in carbon steels, a new hydrogen permeation

Background: Traditional videometric method can not be used in the measurement of large flexible cable-net structure for its large overall size and small partial size. Objective A videometrics technique was proposed in this work to measure the topography and deformation of a large cable net structure. Methods Tiny spots with high brightness (and large gray gradient) are used to mark the cable net nodes

Background Nowadays there is no currently accepted test specimen to measure the mode III fracture toughness of rigid monolithic and composite materials. Objective To propose and evaluate a new and simple test specimen called the Transverse Shear Cracked Plate to characterize the mode III fracture toughness of an epoxy resin. Methods The proposed specimen consists of a cantilever 38 mm × 38 mm square

Background Metal additive manufacturing has extensive application prospects in the aerospace, precision instrument, and biomedical fields, etc. However, the low manufacturing quality of key components is a bottleneck restricting the further development and application of this technology. Because of the extremely complex manufacturing environment, a real-time and online monitoring technology for the

Background In-situ spot weld failure analysis under complex loading conditions is significantly restricted by the enclosed space around the weld nugget. Failure can be only observed at the post-failure stage which provides only limited information of the manner in which damage progresses and leads to crack propagation. Objective Novel testing and analysis techniques were developed to observe the through

Background Although accurate knowledge of material behavior in plane strain tension is important for the modelling of sheet metal forming processes, it is often overlooked in yield function calibration because of experimental characterization challenges. Plane strain notch tensile tests, though experimentally convenient, are subject to stress and strain gradients across the gauge width that complicate

Background Surface topography strongly modifies adhesion of hard-material contacts, yet roughness of real surfaces typically exists over many length scales, and it is not clear which of these scales has the strongest effect. Objective: This investigation aims to determine which scales of topography have the strongest effect on macroscopic adhesion. Methods Adhesion measurements were performed on technology-relevant

Background Optical measurement techniques such as digital image correlation and speckle interferometry have been applied to hole-drilling evaluations of residual stress for some decades. These full-field non-contact measurements can have significant advantages over the traditional strain gauge method. However, optical measurements are still only rarely used for practical measurements outside the research

Background Mechano-electro-chemical coupling during the ion diffusion process is a core factor to determine the electrochemical performance of electrodes. However, relationship between the mechanics and the electrochemistry has not been clarified by experiments. Objective In this work, we conduct an in situ, visual, comprehensive characterization of strain field and Li concentration distribution to

Background The impact strengths of solder joints between an electrical substrate and millimeter- or micrometer-sized electrical components such as resistors and capacitors must be determined when designing the electrical devices. Impact fracture of the device must be also considered due to mounting a lot of small electrical devices on an electrical board at high speed in production of many components

Background Microindentation is a technique with high sensitivity and spatial resolution, allowing for measurements at small-scale indentation depths. Various methods of indentation analysis to determine output properties exist. Objective Here, the Oliver-Pharr Method and Hertzian Method were compared for stiffness analyses of articular cartilage at varying length-scales before and after bioreactor

Background Accurate evaluation of life-limiting failure behavior is a prerequisite to ensure the successful design and application of ceramic matrix composites (CMCs). Objective To investigate life-limiting failure behavior of CMCs, it is necessary to evaluate the in-plane shear strength. Methods In this paper, the in-plane shear strength (IPSS) of two-dimensional carbon fiber reinforced silicon carbide

Background Hydrogels are crosslinked polymer networks that can absorb and retain a large fraction of liquid. Near a critical sliding velocity, hydrogels pressed against smooth surfaces exhibit time-dependent frictional behavior occurring over multiple timescales. The origin of these dynamics is unresolved Objective Here, we characterize this time-dependent regime and show that it is consistent with

Background Measuring true stress–strain curve over a large-strain-range is essential to understand mechanical behavior and simulate non-linear plastic deformation. The digital image correlation (DIC) technique, a non-contact full-field optical measurement technique, is a promising candidate to obtain a long-range true stress–strain curve experimentally. Objective This paper proposes a method for measuring

Background Camera calibration is an essential step for the optical measurement method used in the experimental mechanics. Most plumb line methods focus on solving lens distortions without considering camera intrinsic and extrinsic parameters. Objective In this paper, we propose a full camera calibration method to estimate the camera parameters, including camera intrinsic parameters, extrinsic parameters

Background While near surface residual stress (NSRS) from milling is a driver for distortion in aluminum parts there are few studies that directly compare available techniques for NSRS measurement. Objective We report application and assessment of four different techniques for evaluating residual stress versus depth in milled aluminum parts. Methods The four techniques are: hole-drilling, slotting

Background The effect of loading rate on the fracture properties of materials had been the subject of interest for more than four decades. However, the effect of loading rates on Mixed-mode fracture, involving Modes I and III, is known little due to the complexity of loading conditions and the inertia effect at a high loading rate. Objective The main objective is to develop a framework to investigate

Background Efficient biaxial strain control to study fatigue damage growth in composite materials at the coupon scale level under realistic multi-axial stress states observed in structures is needed. Objective Two biaxial cyclic strain control algorithms, referred to here as the active and the passive control method, are presented as a fatigue testing strategy for composite materials. Method The strain

Background Peel tests are frequently used to perform measurements of adhesive strength for pressure sensitive adhesive (PSA) tapes. Current lab methodologies for 90° peel tests translate the model substrate orthogonally to the peel direction in order to maintain the peel angle, precluding testing from immovable substrates. Objective It was our objective to develop a peel fixture capable of testing

Background Digital Image Correlation (DIC) is a popular experimental technique for measuring full-field deformations in materials. Accurate motion and displacement field reconstruction in DIC depend heavily on the intrinsic material texture or speckle patterns painted on the material prior to deformation. Many traditional techniques such as spray painting, ink stamping, or manual texturizing have provided

Background Digital image correlation (DIC) is a widely used experimental method to measure full-field displacements and strains. This technique compares images of speckle patterns before and after deformation to computationally infer the displacement and strain fields. Of particular interest are complex mechanical phenomena where strains are far from uniform. Objective In such situations, it would

Background Ionic liquids (ILs) have recently attracted considerable attention in tribology owing to their unique physico-chemical properties and promising lubrication performance when used in a wide range of material pairs.  Objective The aim of this review article is to summarize recent advances in our knowledge related to the lubrication mechanisms of neat ILs, with a particular focus on nanoscale

Background The tensile strength along the longitudinal direction of unidirectional carbon fiber reinforced plastics (CFRPs) constitutes important data for the reliable design of CFRP structures. Our earlier reports proposed the formulations for the statistical static, creep, and fatigue strengths of CFRP based on Christensen’s model of the viscoelastic crack kinetics. Objective This study is concerned

Background High-resolution Digital Image Correlation (DIC) measurements have previously been produced by stitching of neighboring images, which often requires short working distances. Separately, the image processing community has developed super resolution (SR) imaging techniques, which improve resolution by combining multiple overlapping images. Objective This work investigates the novel pairing

Background Vortex stability is critically important for applications of type-II superconductors. If some vortices are detached from their pinning sites by external perturbations, the concomitant Joule heat will facilitate further motion of other vortices. This is a positive feedback process, which leads to a flux avalanche in the superconductor. So far, the existing research has not addressed the problem

Background This paper is Part 2 of a study on the scope of the ultrasonic Surface Reflection Method (SRM). Part 1 deals with the theoretical conditions for a satisfactory usage of this method. Objective This second part validates the practical feasibility and reliability of the SRM method by comparison with the conventional Transmission Method (TM) in cases where the latter is applicable. Methods Two

Background This paper deals with the possible field of application of ultrasonic Surface Reflection Method (SRM) to achieve the mechanical characteristics of isotropic materials. This method is based on the measurement of the amplitude of the reflected wave at the interface between reference material and the material to be characterised. Objective: The purpose of Part 1 of this paper is to establish

Background: In synchrotron radiation computed tomography (SR-CT) of mechanical loading process, accurate reconstruction of finite angle projection information shielded by mechanical loading devices is a bottleneck problem. Objective: For accurate characterization, an experimental strategy for in situ SR-CT mechanical loading test was proposed in this manuscript, which was called "finite angle CT reconstruction

A correction to this paper has been published: https://doi.org/10.1007/s11340-021-00702-z

Background High pressure die casting (HPDC) Mg alloy has a hetero-structure in which the microstructures gradually coarsen from the casting surface to the interior, leading to the different elastic–plastic (E-P) transitional behaviors among the layers. Objective In this paper, we quantitively determined the diverse E-P transitions among the HPDC layers and related them to the microstructural evolution

Background: Application of patterns to enable high-resolution Digital Image Correlation (DIC) at the small scale (μm/nm) is known to be very challenging as techniques developed for the macro- and mesoscale, such as spray painting, cannot be scaled down directly. Moreover, existing nano-patterning techniques all rely on harsh processing steps, based on high temperature, chemicals, physical contact,

Background Friction Stir Welding (FSW) causes intense plastic deformation and consequent thermomechanical interactions resulting in a localised heterogeneous microstructure. To understand the weld mechanical behaviour, it is necessary to identify each microstructural sub-region in the weld. Objective Determine the relationship between the local microstructure and mechanical behaviour of the different

Background Developments in digital image correlation (DIC) in the last decade have made it a practical and effective optical technique for displacement and strain measurement at high temperatures. Objective This overview aims to review the research progress, summarize the experience and provide valuable references for the high-temperature deformation measurement using DIC. Methods We comprehensively

Background Subsurface mechanisms can greatly affect the mechanical behavior of biological materials, but observation of these mechanisms has remained elusive primarily due to unfavorable optical characteristics. Researchers attempt to overcome these limitations by performing experiments in biological mimics like hydrogels, but measurements are generally restricted due to the spatio-temporal limitations

Background It is common practice to use various residual stress measurement methods to complement each other and fully define a through-thickness stress distribution. Incremental hole-drilling (IHD) and X-ray diffraction (XRD) are two of the most widely used techniques. Although IHD readily provides stress data to some depth, the method is susceptible to large stress uncertainties near the surface

Background Digital Image and Volume Correlation (DIC and DVC) are non-contact measurement techniques that are used during mechanical testing for quantitative mapping of full-field displacements. The relatively high noise floor of DIC and DVC, which is exasperated when differentiated to obtain strain fields, often requires some form of filtering. Techniques such as median filters or least-squares fitting

Background High-velocity oxy-fuel (HVOF)-sprayed metallic coating can be used to create a surface layer that plays a significant role in enhancing the overall strength, stiffness, and fatigue life of the treated material. The micro-deformation around a single impacted particle is a critical factor that must be considered for the optimization of the HVOF process. Objective In this study, the micro-deformation

Background Digital image correlation (DIC) has become a superior tool for surface deformation measurement so far. In order to improve its measurement accuracy, different error models have been developed to reveal the cause of various error. Objective An error model unifying the random error and systematic error should be valuable. Method In this paper, a frequency-domain error model for 2D-DIC is established

Background Digital Image Correlation (DIC) is widely used for remote and non-destructive structural health evaluation of infrastructure. Current DIC applications are limited to relatively small areas of structures and require the use of stationary stereo vision camera systems that are not easy to transfer and deploy in remote areas. Objective The enclosed work describes the development and validation

Background Soft tribology is increasingly important in the design and engineering of materials used in robotics, haptics, and biomechanics studies. When patterned surfaces are part of a lubricated tribopair that undergoes sliding and compressive deformation, the patterns experience a bending strain that affects the lubrication film thickness and elastohydrodynamic friction. The contribution of bending

Background Ratcheting is an important mechanical behavior of metals and alloys, which is caused by the repeated accumulations of tensile and compressive strain in circle load. However, the current characterization methods of ratcheting effect are mostly based on standardized testing and uniform data, and more comprehensive field measurement data cannot be used. Objective This paper focuses on how to

Background Dislocation dynamic simulations are intended as a tool to understand and predict the mechanical behavior of metallic materials, but its prediction has never been directly verified by experiments due to differences in specimen strain rate and size. Objective In this work, a comprehensive experimental framework is proposed to attempt direct comparison between experiments and discrete dislocation

Background With the recent increase in digital image correlation (DIC) applications, it is important to improve the computational efficiency of DIC and realize the closed loop control of systems. Objective A real-time three-dimensional (3D) DIC method for large deformation and rotation measurements is proposed in this paper. Methods To solve the problem of initial guess estimation under large deformation

Background Microwave imaging is widely used in many areas involving non-destructive testing, biomedical imaging, radar detection and imaging, etc. However, there is a lack of microwave 3D imaging methods with lateral and depth super-resolution. Objective We propose a microwave near-field 3D super-resolution imaging method based on the near-field scanning microwave microscopy (NSMM) technique, enabling

Background As a full-field optical metrology, projection moiré approach has been widely used in many engineering applications. The modeling of moiré system and the calibration, including the calibration of relationship between the moiré phase and object’s height, and the calibration of optical system parameters, are the key points in this method as they directly determine the measurement accuracy and

Background Load-relaxation under a constant state of deformation is a common characteristic of hydrated materials, including hydrogels and biological tissues. Overall, mechanical response in such materials is a strong function of underlying structure, which in hydrogels depends on whether the gel is formed through physical or chemical cross-linking. In order to use hydrogels in biomedical applications

Background Continuous welded rails (CWR) are subjected to thermal effects that may lead to buckling or fracture during warm or cold seasons, respectively. The modal characteristics (frequency and mode shapes) of CWR may reveal important information about the thermal stress that can be used to prevent rail failures. Objective The primary objective of this study is to prove a contactless method to monitor

Background As new applications demand the synthesis and validation of materials with specific mechanical performance targets, there is a need for improved characterization and understanding of reduced length-scale deformation processes which govern mechanical behavior (i.e., dislocation slip and twinning). The heterogeneous nature of deformation in polycrystalline materials makes it essential to employ

Background The contact and frictional response of a hydrogel is dependent on the polymer structure at the gel surface. Recent work has shown that different mold materials in contact with the gel during polymerization will affect the resulting polymer density. Objective The tribological response of a gel with a ‘brushy’ less-dense polymer surface has not been thoroughly studied. Our goal was to perform

Background Conventional composites used in damping applications exhibit an undesirable tradeoff between stiffness and energy dissipation. Recent research demonstrates that it is possible to simultaneously achieve increased stiffness and energy dissipation for a configuration of a viscoelastic polymer matrix placed in parallel with a negative stiffness structure (NSS). This configuration resulted in

Background The burst testing technique is used to determine the failure hoop stress of tubes that are subjected to internal pressure. In that technique, the tube is subjected to internal high fluid pressure until it bursts. This testing technique is costly and is not suitable if the available tube material is limited. Objective In this paper, a novel design of a ring expansion testing rig is presented

Background The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such distributions may be determined by the microstructural feature tracking method. However, the strain accuracy and the sources of uncertainty of this method are not well quantified yet. Objective Evaluate the accuracy of local strain

Background Given the inherent manufacturing variabilities and potential for in-service damage of composite parts, the identification of the elastic properties of composites is important to ensuring the safety and the proper performance of the part. Objective The primary objective of this manuscript is to determine, nondestructively, the elastic properties of composite parts, whether as in-situ components

Background Soft, biological, and bio-inspired materials are often compositionally heterogeneous and structurally anisotropic, and they frequently feature graded or layered organizations. This design complexity enables exceptional ranges in properties and performance yet complicates a fundamental understanding of the contact mechanics. Recent studies of soft gel layers have relied on Hertzian or Winkler

Background Uncertainty quantifications are required for any measurement result to be meaningful. Objective The present work aims at deriving and comparing a priori estimates of displacement uncertainties in T3-stereocorrelation for a setup to perform high temperature tests. Methods Images acquired prior to the actual experiment (i.e.,at room temperature) were registered using 3-noded triangular elements

Background Digital image correlation (DIC) method is a non-interference and non-contact full-field optical measurement technology. DIC’s measurement accuracy is largely determined by the image acquisition system and the quality of the speckle pattern. Objective Although the optimal speckle pattern has been designed theoretically, the optimization process does not consider the influence of the imaging

Background Additive manufacturing (AM) is becoming increasingly popular, but standards for critical defect sizes and porosity levels have not been fully established. The wide range of flexibility offered by AM is unable to be exploited by designers if they do not have confidence in their components’ mechanical behavior. Objective The goal of this study was to understand how the factors of specimen