Uniaxial Compressive Force Research Articles

Effect of Applied Stress on the Interfacial Kinetics, Ionic Conductivity, and Other Phenomena in Thin-Film Solid-State Batteries

Controlled stress is critical to both fabrication and operation of solid-state batteries to ensure pristine, low-impedance interfaces. The effects of externally applied stresses on overall cell performance and degradation due to altered thermodynamics, interfacial kinetics, and bulk transport of the active species have been studied in several prior works. In addition to the applied stack pressure which can vary up to 100s MPa, internal and localized stresses up to a few ~1 GPa can be generated from volume changes during charge and discharge. Electrode volume changes can result in cracking and delamination, causing loss of conductive pathways and active electrode-electrolyte area, and electrolyte fracture in the case of dendrite growth. The extent of these stress-electrochemistry couplings depends on the material and geometry of interfaces that affects the local stress distribution. To decouple some of these stress-potential, stress-kinetics, and stress-transport coupling phenomena, we use a nanoindenter platform to apply controlled uniaxial compressive forces to a thin-film electrochemical devices and batteries1. Interfaces in a thin-film sample can be uniform and planar over large areas, helping us study the effect of stress on the interfacial electrochemistry more directly and with greater quantitative accuracy. In this work we present our observations and analysis on the direct electrochemical-mechanical coupling in thin-film TiO2 and V2O5 metal oxide thin films as the working electrode with the single-ion Li+ conductor solid electrolyte LiPON. Preliminary results show that external uniaxial compressive load affects the electrochemistry observed through cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements on thin-film batteries with TiO2 and V2O5 electrodes.

Energy-based solution for the plastic buckling of stainless steel circular cylindrical shells

This paper presents an energy-based approximate solution for the plastic buckling of a stainless steel circular cylindrical shell due to a uniaxial compressive force. The solution is based on Ritz method. The implementation of the method is simplified by utilizing the Ramberg-Osgood model along with the total deformation theory to formulate the plasticity constitutive equations. The concept of minimum potential energy yields a single highly non-linear equation to be solved by Mathematica. The accuracy of the obtained solution is verified numerically by the finite element method, using ABAQUS, and experimentally by comparison with several experimental results obtained from the literature. The obtained results show excellent agreement among the analytical, numerical and experimental solutions, with a maximum deviation of 9% between the analytical and experimental values. A parametric study is performed using the validated analytical solution aiming to further investigate the effect of various stainless steel material parameters. Based on the parametric study results, closed-form expressions are derived for the buckling stress.

Effects of precipitate on the phase transformation of single-crystal NiTi alloy under thermal and mechanical loads: A molecular dynamics study

Molecular dynamics simulations have been carried out in this study to investigate the stress-induced and temperature-induced phase transformations in NiTi shape memory alloy in the presence of Ni4Ti3 precipitate. NiTi alloys form the most popular class of shape memory alloys that have many applications in various industries. Therefore, computational simulation of the material behavior can extend our understanding of the material properties and help the development of alloys with tailored properties. In the simulations, an Ni4Ti3 precipitate (with a rhombohedral crystal structure) was generated and embedded into the NiTi matrix (having a B2 crystal structure). The transformation temperatures were computed by applying a cooling-heating cycle starting from a high temperature. At the austenitic state (at a temperature above Af), a monotonically increasing uniaxial compressive force was applied to the models with and without precipitate and, as expected, both models exhibited superelastic behavior. Furthermore, similar models were made for different directions of the compressive force relative to the crystallographic directions to study the direction dependence of the mechanical response. For all the loading directions that phase transformation happened, a larger hysteresis occurred for the precipitated model compared to the pristine NiTi due to the hindrance of reverse phase transformation in presence of the precipitate. The results show that the precipitate has a pronounced effect on the superelastic behavior in 〈100〉 loading directions.

Mechanical behavior of ZTAp/40Cr three-dimensional interpenetrated composites under compression

We used a hierarchical algorithm to study the mechanical behavior of the ZTAp/40Cr three-dimensional (3D) interpenetrating composite under uniaxial compressive force. First, we developed a microscopic uniformly distributed representative volume element (RVE) model to measure the properties of the ZTAp/40Cr 3D interpenetrating composite under uniaxial compression. We studied the effect of the interfacial parameters on the properties of homogeneous composites. Furthermore, we equated the properties measured using microscopic uniform distribution RVE model with the 3D interpenetrating composite zone properties to analyze the power, durability, and harm modes of the 3D interpenetrating composites with 35% and 50% volume fraction in the composite zone. We observed that the interface strength and fracture energy significantly influence the compression properties of the composite. Moreover, the simulations for the macroscopic 3D interpenetrated composites are consistent with the experimental structural mechanics. Our findings can serve as a foundation for further research on the properties of 3D interpenetrated conformal composites.

Chemical physics of superconductivity in layered yttrium carbide halides from first principles

We perform a thorough first-principles study on superconductivity in yttrium carbide halide ${\mathrm{Y}}_{2}{X}_{2}{\mathrm{C}}_{2}$ ($X=\mathrm{Cl}$, Br, I) whose maximum transition temperature (${T}_{\mathrm{c}}$) amounts to $\ensuremath{\sim}10$ K. A detailed analysis on the optimized crystal structures reveals that the ${\mathrm{Y}}_{2}{\mathrm{C}}_{2}$ blocks are compressed uniaxially upon the halogen substitution from Cl, Br to I, contrary to the monotonic expansion of the lattice vectors. With a nonempirical method based on the density functional theory for superconductors within the conventional phonon mechanism, we successfully reproduce the halogen dependence of ${T}_{\mathrm{c}}$. An anomalously enhanced coupling of one ${\mathrm{C}}_{2}$ libration mode is observed in ${\mathrm{Y}}_{2}{\mathrm{I}}_{2}{\mathrm{C}}_{2}$, which implies a possible departure from the conventional pairing picture. Utilizing the Wannier representation of the electron-phonon coupling, we show that the halogen electronic orbitals and ionic vibrations scarcely contribute to the superconducting pairing. The halogen dependence of this system is hence an indirect effect of the halogen ions through the uniaxial compressive force on the superconducting ${\mathrm{Y}}_{2}{\mathrm{C}}_{2}$ blocks. We thus establish a quantitatively reliable picture of the superconducting physics of this system, extracting a unique effect of the atomic substitution which is potentially applicable to other superconductors.

A new equilibrium solution for masonry spiral stairs

This paper considers stone or brick staircases that appear to cantilever from an exterior wall as they spiral upward. A new equilibrium solution is proposed that does not rely on cantilevering from the wall. Unlike previously proposed membrane solutions, the proposed new analytical solution, called Linear Arch Static Analysis (LASA), is based on a 1D no-tension filament, or a set of such 1D filaments (that -by following Rankine’s definition- we call space linear arches), and is therefore particularly efficient. Each space linear arch represents a compressive element that spirals down the staircase, simulating a compressive force that is transferred through and between each stair. In addition, the equilibrium of each filament requires the contribution of horizontal uniaxial compressive forces which are provided by the exterior wall support and transmitted horizontally through each stair. The lines of action of such uniaxial compressive stresses are entirely contained inside the masonry. The new solution is applied to both circular and elliptical stairs to demonstrate the new equilibrium solutions, but also to quantify and highlight the magnitude of resulting forces and the efficiency of the solution. The effect of geometric variations on internal forces are also explored to evaluate the efficiency and feasibility of various potential stair geometries.

Experimental and Numerical Investigations of Ultimate Strength of Imperfect Stiffened Plates of Different Slenderness

Abstract The objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.

Experimental and numerical investigations on slender panels with holes under symmetrical localised loads

Perforated steel girders under a single or combined in plane loading have been largely studied in the literature. However, such investigations were trusted on the numerical modelling and FEM analysis and due to the lack of experimental results in most cases, the accuracy of the numerical model and the consideration of imperfections in the FEM analyses are open to reflexion. In this paper, a series of experimental tests are performed to study the post-critical behaviour of perforated steel girders. Ten full scales steel girders were tested under uniaxial compressive force. Amongst them, four were used as control specimens whereas a circular hole was located in the center of the other six. The parameters such as the geometry of the web plate, the position of the hole and the plate slenderness are found as those most influencing the post-critical behaviour. Finally, the experimental results were used to validate the intensive numerical analyses. The results obtained showed the strong influence of combined geometrical imperfections and residual stresses on the mid-plane Von Mises stresses.

Particle Strength of Calcareous Sand in Nansha Islands, South China Sea

Abstract Single particle strength is the main factor that influences particle breakage. In order to explore particle strength characteristics and the relationship between the strength and size of calcareous sand from the South China Sea, single particle crushing tests were conducted using self-made test equipment. Hundreds of particles (0.72–3.12 mm) divided into three groups of different sizes were used to perform the test. The results show that the strength characteristics of the particles were similar to those of a typical brittle material and were lower than that of quartz sand. Under flat unconfined compression, two types of uniaxial compressive force–displacement curves were defined according to the tests, related to the shape and structure of the calcareous sand particles. Statistical data analysis shows that the calcareous sand particles’ strength is in good agreement with the Weibull distribution. The particle crushing strength decreases as the particle diameter increases. Different shapes of calcareous sand particles show different strength characteristics. In addition, the mineral composition, microstructure, distribution of inner voids and fracture are related to the particle strength of calcareous sand.

In Vitro Weight-Loaded Cell Models for Understanding Mechanodependent Molecular Pathways Involved in Orthodontic Tooth Movement: A Systematic Review.

Cells from the mesenchymal lineage in the dental area, including but not limited to PDL fibroblasts, osteoblasts, and dental stem cells, are exposed to mechanical stress in physiological (e.g., chewing) and nonphysiological/therapeutic (e.g., orthodontic tooth movement) situations. Close and complex interaction of these different cell types results in the physiological and nonphysiological adaptation of these tissues to mechanical stress. Currently, different in vitro loading models are used to investigate the effect of different types of mechanical loading on the stress adaptation of these cell types. We performed a systematic review according to the PRISMA guidelines to identify all studies in the field of dentistry with focus on mechanobiology using in vitro loading models applying uniaxial static compressive force. Only studies reporting on cells from the mesenchymal lineage were considered for inclusion. The results are summarized regarding gene expression in relation to force duration and magnitude, and the most significant signaling pathways they take part in are identified using protein-protein interaction networks.

Buckling analysis of composite laminated skew plate of variable thickness

Tapered composite plates are increasingly being used in various engineering applications. In variable-thickness laminate, the material and geometric discontinuities at ply drop-off locations leads to significant discontinuities in stress distributions. Elastic stability of variable-thickness composite laminated skew plate subjected to uniaxial in-plane compressive forces has been studied. The buckling analysis of the skew laminate plates of variable thickness are carried out by the bifurcation buckling implemented in finite element program ANSYS. A parametric study on tapered composite skew plate is conducted, considering the effects of skew angles, laminate layups, taper angles, boundary conditions on the buckling resistance of skew composite laminate plates are presented.

Influence of a Ni Metal Phase and Geometrical Structures of YSZ in Ni-YSZ SOFC Anode to Its Mechanical Properties

Conventional SOFCs, which adopt an anode supported type cell design, use the porous cermet of Ni and YSZ as the anode. On the viewpoint of mechanical design, the anode is an important component next to the electrolyte because it prevents the electrolyte from destruction caused by thermal stress, chemical stress, and outer force. However, the anode also show uncertainly in the response to outer force, which is most fundamental property for mechanical design. This uncertainly is due to the existence of Ni metal phase and complex geometrical structure in the anode (Ni-YSZ). To maintain electrical conductivity, gas permeability, and catalytic activity, the anode consist of Ni, YSZ and porosity, which volumatic ratio are almost same, and each phase are continuously connected in the anode, in other words, three networks co-exist in the anode. At high temperature close to ½ of melting temperature of Nickel(Tm=1455oC), Nickel is easily deformed plastically. By contrast, YSZ(Tm=2700oC) is still brittle. In addition, each network are non-uninform. So, stress concentration and bending occur by outer force applying. These things make behavior more complex. However, the response of outer force and its relationship between the response to microstructure have not been well studied. Yield strength of nickel (ca.150MPa) at room temperature is close to fracture strength of YSZ(ca. 200MPa). Therefore, at room temperature, the anode cermet show brittle behavior because YSZ network is fractured at the same time of nickel network yields. However, at SOFC operating temperature, nickel yield strength becomes very low (ca.20MPa@800oC) . In this situation, nickel network yields much smaller stress than fracture of YSZ network. Geometrical structure in cermet is categorized to two types. First type is often used for high speed tools, and, guest material shows isolated distribution in host material. Second type is used for the anode, and host and guest materials make continuous networks in cermet, respectively. Response to outer force in first type are dominated by host materials. However, that in second type (SOFC Ni-YSZ anode) are not studied well.Therefore, we studied creep curves (response to small stress), stress-strain curves (response to large stress) in Ni-YSZ. Furthermore, we evaluated the influence of volume ratio between Ni and YSZ to fracture toughness. Based on the results, the influence of a Ni metal phase and geometric structures of YSZ to mechanical properties were discussed.Three chemical compositions (Ni vol% 30, 44, 58 : Ni30, Ni44, Ni58) of Ni-YSZ were tested. Both creep curves and stress-strain curves showed different behavior to outer forces from porous Ni metals or porous YSZ. In the case of creep test, activation of creep rate varied from that of YSZ to that of Ni metal, and this variation was suggested to be related to accumulated strain in Ni-YSZ specimens. Ni-YSZ specimens showed different fracture modes to outer forces from different directions. Under uniaxial compressive force, Ni44, Ni58 specimens was squished at the strain range over 1%, and Ni44 specimens were torn under bending force. These results suggested that mechanical properties were strongly influenced by the rigidity of YSZ network in Ni-YSZ. In addition, we discuss about the rigidity of YSZ networks at the presentation.

Mechanical loading of cartilage explants with joint-specific loading patterns modulates gene expression of lubricin and catabolic matrix enzymes

• Excessive mechanical loading can lead to damage and loss of matrix components due to the synthesis of catabolic enzymes such as MMPs and ADAMTS. • Cartilaginous surfaces, such as the temporomandibular joint (TMJ), spend most of the time in relative motion with a constant translation of the contact zone [1,2]. • Such migrating contacts are essential for tissues function [3]. • Recent mechanobiological studies almost exclusively apply relatively simple loading regimens such as uniaxial compressive and/or shear forces while keeping the contact area stationary. 

Biomechanical Analysis of Subpectoral Biceps Tenodesis

Background: Humeral fracture after subpectoral tenodesis of the long head of biceps tendon (LHB) is a rare but devastating complication. Purpose: To determine whether malpositioned (laterally eccentric) tenodesis screw placement has an influence on humerus strength reduction compared with central placement. Study Design: Controlled laboratory study. Methods: Two groups, each consisting of 10 matched pairs of human humeri, were used for this study. Biceps tendons were fixed subpectorally with 8-mm screws in unicortical 8-mm sockets. In the first group, the socket was placed concentrically in the bicipital groove and the tendon was fixed with an interference screw. In the second group, the socket was malpositioned 30% eccentrically to the lateral (tension) side of the humerus. Contralateral humeri remained intact as positive controls. Specimens were aligned in 40° of abduction, and a uniaxial compressive force was applied to the humeral head until failure. Strength reduction was reported as percentage reduction in ultimate failure load between paired humeri. Relative defect size was calculated as a percentage of the total humeral width at the height of the tenodesis. Results: Laterally eccentric malpositioned biceps tenodeses significantly decreased humeral strength compared with intact (mean change, −25%; SD, 23%; P = .017), while concentrically placed biceps tenodeses did not (mean change, −10%; SD, 15%; P = .059). A linear regression between relative defect size and strength reduction in the malpositioned group showed a significant negative linear correlation (beta = −2.577; R2 = 0.423; P = .042). Conclusion: Humeral fracture after subpectoral tenodesis of the LHB is a complication that may be minimized with careful surgical technique. Laterally eccentric malpositioned biceps tenodesis caused significant reduction (25%) in humeral strength, which might be clinically relevant and contribute to postsurgical humeral shaft fracture. Strength reduction was also significantly correlated with relative defect size. Surgeons using this technique should ensure central and orthogonal placement of the socket, especially in smaller individuals. This study lends biomechanical evidence to support the clinical procedure of a correctly, concentrically placed tenodesis screw. Clinical Relevance: These biomechanical results indicate that in a clinical setting, special attention should be drawn to patient selection for LHB tenodesis. This study reveals that central screw positioning is critical, particularly in high-impact and overhead athletes, as well as for patients with small humeral widths or osteoporotic bone quality. Alternative surgical options such as smaller screws or other fixation methods might be considered to diminish the postoperative risk of humeral fracture.

Finite element modelling of the mechanics of discrete carbon nanotubes filled with ZnS and comparison with experimental observations

The mechanical response to a uniaxial compressive force of a single carbon nanotube (CNT) filled (or partially-filled) with ZnS has been modelled. A semi-empirical approach based on the finite element method was used whereby modelling outcomes were closely matched to experimental observations. This is the first example of the use of the continuum approach to model the mechanical behaviour of discrete filled CNTs. In contrast to more computationally demanding methods such as density functional theory or molecular dynamics, our approach provides a viable and expedite alternative to model the mechanics of filled multi-walled CNTs.

Effects of structural defects on the compressive buckling of boron nitride nanotubes

In this paper, we examined the buckling of perfect and defective armchair boron nitride nanotubes with three types of vacancy defects, i.e. B- and N- single vacancy defects and B–N- double vacancy defect, using molecular dynamics simulations. To this end, all systems were modeled with a Tersoff-type potential, which is able to accurately describe covalent bonding of BN systems. We applied external uniaxial compressive forces to the nanotubes in vacuum and derived the critical buckling loads and strains, at room temperature in an NVT-ensemble. Our results showed significant differences between the critical buckling strengths of pristine and defective nanotubes. The resistance to axial buckling decreased with the introduction of one vacancy defect, and the B–N- double vacancy was the most seriously damaged structure, followed by B-vacancy and N-vacancy defects. Furthermore, the B-vacancy was shown to have the most significant effect on the decrease of the critical buckling strain. This can be attributed to the excessive asymmetries and perturbations induced in the structure of the nanotube and the local deformations around the defective site around the B-vacancy, even before loading. Moreover, results show that reduction in the buckling strength of the nanotube due to the presence of more than one B-vacancy defect depends on their distribution. If the two or three defects are close to each other, they act as a single point of weakness and the critical buckling load is only slightly reduced (similar to the existence of only one vacancy defect). However, if the defects are at more distant points, the critical buckling load may experience a higher decrease. Results show that vacancy defects play a critical role in the compressive buckling performance of boron nitride nanotubes and special attention must be paid to the presence of structural defects when designing members against buckling, especially for micro- and nano-electro-mechanical systems. On the other hand, defect engineering is a great means for tailoring the buckling strength of boron nitride nanotubes, in cases where the nanotube is expected to absorb energy through compressive buckling deformation and is not designed against, but for buckling.

Strength Test and Forecast of CFRP-Confined Concrete Preloaded under Uniaxial Compressive Force

In this paper, preloaded specimen is used and confined by CFRP to act as structural concrete member in service. And the test to examine the behavior of the test piece has been carried on. After this, the strength and its influence factor has been analyzed. Referring the former strength model, the particular factor axial ratio B of the specimen this test has been taken into account.Then refering the existing model, the improvement has been made. And the new strength model for forecast to CFRP confined preloaded concrete is put forward, also it can be used as reference for reinforcing design of engineering.

Ultrasonic measurements of breast viscoelasticity

In vivo measurements of the viscoelastic properties of breast tissue are described. Ultrasonic echo frames were recorded from volunteers at 5 fps while applying a uniaxial compressive force (1-20 N) within a 1 s ramp time and holding the force constant for up to 200 s. A time series of strain images was formed from the echo data, spatially averaged viscous creep curves were computed, and viscoelastic strain parameters were estimated by fitting creep curves to a second-order Voigt model. The useful strain bandwidth from this quasi-static ramp stimulus was 10(-2) < or = omega < or = 10(0) rad/s (0.0016-0.16 Hz). The stress-strain curves for normal glandular tissues are linear when the surface force applied is between 2 and 5 N. In this range, the creep response was characteristic of biphasic viscoelastic polymers, settling to a constant strain (arrheodictic) after 100 s. The average model-based retardance time constants for the viscoelastic response were 3.2 +/- 0.8 and 42.0 +/- 28 s. Also, the viscoelastic strain amplitude was approximately equal to that of the elastic strain. Above 5 N of applied force, however, the response of glandular tissue became increasingly nonlinear and rheodictic, i.e., tissue creep never reached a plateau. Contrasting in vivo breast measurements with those in gelatin hydrogels, preliminary ideas regarding the mechanisms for viscoelastic contrast are emerging.

Strength Measurement of Ceramic Spheres Using a Diametrally Compressed “C‐Sphere” Specimen

A “C‐sphere” specimen geometry was conceived and developed to measure failure stress of bearing‐grade silicon nitride (Si3N4) balls caused by tension at the ball's surface. The induced method of fracture also allows for the study of surface‐located strength‐limiting flaws in ceramic spheres. A slot is machined into the balls to a set depth to produce the C‐sphere geometry. A simple, monotonically increasing uniaxial compressive force produces an increasing tensile stress at the C sphere's outer surface that ultimately initiates fracture. The strength is determined using a combination of failure load, C‐sphere geometry, and finite element analysis. Additionally, the stress field was used to determine the effective areas and effective volumes of a C‐sphere as a function of Weibull modulus. To demonstrate this new specimen, C‐sphere flexure strength distributions were determined for three commercially available bearing‐grade Si3N4 materials (NBD200, SN101C, and TSN‐03NH), and differences among their characteristic strengths and Weibull moduli were found.

Buckling optimization of laminated cylindrical panels subjected to axial compressive load

The buckling resistance of fiber-reinforced laminated cylindrical panels with a given material system and subjected to uniaxial compressive force is maximized with respect to fiber orientations by using a sequential linear programming method together with a simple move-limit strategy. The significant influences of panel thicknesses, curvatures, aspect ratios, cutouts and end conditions on the optimal fiber orientations and the associated optimal buckling loads of laminated cylindrical panels have been shown through this investigation.