Yield Strain Research Articles

Effect of Hard Plastic Waste on the Quality of Recycled Polypropylene Blends

The recycling of plastic waste is undergoing fast growth due to environmental, health and economic issues, and several blends of post-consumer and post-industrial polymeric materials have been characterized in recent years. However, most of these researches have focused on plastic containers and packaging, neglecting hard plastic waste. This study provides the first experimental characterization of different blends of hard plastic waste and virgin polypropylene in terms of melt index, differential scan calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties (tensile, impact and Shore hardness) and Vicat softening test. Compared to blends based on packaging plastic waste, significant differences were observed in terms of melt flow index (about 10 points higher for hard plastic waste). Mechanical properties, in particular yield strain, were instead quite similar (between 5 and 9%), despite a higher standard deviation being observed, up to 10%, probably due to incomplete homogenization. Results demonstrate that these worse performances could be mainly attributed to the presence of different additives, as well as to the presence of impurities or traces of other polymers, other than incomplete homogenization. On the other hand, acceptable results were obtained for selected blends; the optimal blending ratio was identified as 78% post-consumer waste and 22% post-industrial waste, meeting the requirement for injection molding and thermoforming.

High-throughput assays show the timescale for phagocytic success depends on the target toughness.

Phagocytic immune cells can clear pathogens from the body by engulfing them. Bacterial biofilms are communities of bacteria that are bound together in a matrix that gives biofilms viscoelastic mechanical properties that do not exist for free-swimming bacteria. Since a neutrophil is too small to engulf an entire biofilm, it must be able to detach and engulf a few bacteria at a time if it is to use phagocytosis to clear the infection. We recently found a negative correlation between the target elasticity and phagocytic success. That earlier work used time-consuming, manual analysis of micrographs of neutrophils and fluorescent beads. Here, we introduce and validate flow cytometry as a fast and high-throughput technique that increases the number of neutrophils analyzed per experiment by two orders of magnitude, while also reducing the time required to do so from hours to minutes. We also introduce the use of polyacrylamide gels in our assay for engulfment success. The tunability of polyacrylamide gels expands the mechanical parameter space we can study, and we find that high toughness and yield strain, even with low elasticity, also impact the phagocytic success as well as the timescale thereof. For stiff gels with low-yield strain, and consequent low toughness, phagocytic success is nearly four times greater when neutrophils are incubated with gels for 6 h than after only 1 h of incubation. In contrast, for soft gels with high-yield strain and consequent high toughness, successful engulfment is much less time-sensitive, increasing by less than a factor of two from 1 to 6 h incubation.

Experimental study of flexural behaviour of high strength steel (HSS) ‐ Engineered Cementitious Composites (ECC) composite beam with profiled steel sheeting

AbstractDue to its high compressive strain of at least 0.5%, which is higher than both the yield strain (0.35%) of high strength steel (HSS) and the compressive strain (0.23%) of normal strength concrete (NSC), Engineered Cementitious Composites (ECC) is a material with high potential to replace NSC in HSS composite beam construction. This study reports an experimental investigation on the flexural behaviour of HSS‐ECC composite beam fabricated by using HSS I‐section in conjunction with hybrid polyethylene‐steel fibers (PE‐ST) ECC slab. Shear connection between the HSS I‐section and the top PE‐ST ECC slab was constructed by using normal profiled steel sheeting and headed shear studs. A HSS‐ECC composite beam and a HSS‐NSC composite beam were cast and tested under four‐point bending. The test results revealed that a large area of HSS I‐section in HSS‐ECC composite beam yielded compared to only a small yielded area of which in the HSS‐NSC counterpart despite the fact that both composite beams have identical configuration and silimar mechanical properties. The HSS‐NSC beam underwent longitudinal shear failure while in contrast, the HSS‐ECC beam failed by flexure and exhibited great ductility.

Compressive Properties and Constitutive Model of Semicrystalline Polyethylene.

The mechanical properties of polyethylene (PE) materials are greatly influenced by their molecular structures, environmental temperature, and strain rate. In this study, static and dynamic compression tests were performed on two semicrystalline PE materials—ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE). The stress–strain curves of HDPE and UHMWPE under uniaxial compression at temperatures of −40–120 °C and strain rates of 0.001–5500 s−1 were obtained. The research findings suggest that both the UHMWPE and HDPE showed significant strain rate-strengthening effect and temperature-softening effect. In particular, HDPE exhibited better compression resistance and high-temperature resistance. The relationships between the yield stress and temperature and between the yield stress and strain rate for both materials were fitted, and the Cowper–Symonds constitutive model was built while considering the temperature effect. The parameters of the constitutive model were obtained and input into LS-DYNA software to simulate the dynamic compression process of HDPE. The simulation result was consistent with the test result, validating the accuracy of the constitutive parameters.

Morphological and mechanical characterization of bone phenotypes in the Amish G610C murine model of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a hereditary bone disease where gene mutations affect Type I collagen formation resulting in osteopenia and increased fracture risk. There are several established mouse models of OI, but some are severe and result in spontaneous fractures or early animal death. The Amish Col1a2G610C/+ (G610C) mouse model is a newer, moderate OI model that is currently being used in a variety of intervention studies, with differing background strains, sexes, ages, and bone endpoints. This study is a comprehensive mechanical and architectural characterization of bone in G610C mice bred on a C57BL/6 inbred strain and will provide a baseline for future treatment studies. Male and female wild-type (WT) and G610C mice were euthanized at 10 and 16 weeks (n = 13-16). Harvested tibiae, femora, and L4 vertebrae were scanned via micro-computed tomography and analyzed for cortical and trabecular architectural properties. Femora and tibiae were then mechanically tested to failure. G610C mice had less bone but more highly mineralized cortical and trabecular tissue than their sex- and age-matched WT counterparts, with cortical cross-sectional area, thickness, and mineral density, and trabecular bone volume, mineral density, spacing, and number all differing significantly as a function of genotype (2 Way ANOVA with main effects of sex and genotype at each age). In addition, mechanical yield force, ultimate force, displacement, strain, and toughness were all significantly lower in G610C vs. WT, highlighting a brittle phenotype. This characterization demonstrates that despite being a moderate OI model, the Amish G610C mouse model maintains a distinctly brittle phenotype and is well-suited for use in future intervention studies.

An Injectable Meta-Biomaterial: From Design and Simulation to In Vivo Shaping and Tissue Induction.

A novel type of injectable biomaterial with an elastic softening transition is described. The material enables invivo shaping, followed by induction of 3D stable vascularized tissue. The synthesis of the injectable meta-biomaterial is instructed by extensive numerical simulation as a suspension of irregularly fragmented, highly porous sponge-like microgels. The irregular particle shape dramatically enhances yield strain for invivo stability against deformation. Porosity of the particles, along with friction between internal surfaces, provides the elastic softening transition. This emergent metamaterial property enables the material to reversibly change stiffness during deformation, allowing native tissue properties to be matched over a wide range of deformation amplitudes. After subcutaneous injection in mice, predetermined shapes can be sculpted manually. The 3D shape is maintained during excellent host tissue integration, with induction of vascular connective tissue that persists to the end of one-year follow-up. The geometrical design is compatible with many hydrogel materials, including cell-adhesion motives for cell transplantation. The injectable meta-biomaterial therefore provides new perspectives in soft tissue engineering and regenerative medicine.

Effect of plasticizer and zein subunit on rheology and texture of zein network

Zein can form viscoelastic network, similar to gluten network, to support the weak structure of gluten-free dough caused by the lack of gluten, which greatly improves the textural quality of gluten-free foods. The effect of plasticizer and zein subunit on viscoelasticity of zein network was studied. In this study, total zein (comprising α-, β- and γ-subunits) or α-zein (comprising mainly α-subunit) were used to prepare network with two plasticizer, ethanol or acetic acid, at room temperature, and the glass transition temperature, rheological properties, textural properties, protein secondary structure, and microstructure of the networks were analyzed. The glass transition temperature of total zein was higher than that of α-zein due to β- and γ-zein. The zein network with acetic acid could maintain its viscoelasticity consistently, while the zein network with ethanol hardened gradually. The zein network with acetic acid had a larger yield strain, higher cohesive force, and stronger resistance to external stress than the zein network with ethanol. The existence of β- and γ-zein in total zein could increase the yield strain and cohesive force of zein network. After zein transformed from solid particle to viscoelastic network, its ordered secondary structures decreased, and disordered secondary structures increased. The more plasticized zein was, the more uniform and ordered zein network was. It is concluded that rheological and textural properties of zein network were both subunit and plasticizer-dependent, and these properties of total zein network with acetic acid was the closest to those of gluten network.

High-temperature deformation in bulk polycrystalline hafnium carbide consolidated using spark plasma sintering

In this study, we report the three-point flexural strength and fracture toughness of monolithic hafnium carbide up to 2000 °C. HfC with different grain sizes was consolidated using the spark plasma sintering method. Coarse-grained monoliths showed a weak dependence on the strain rate during high-temperature tests at 1600 °C–2000 °C. In contrast, results for the ceramics with a grain size below 20 μm indicated a positive dependence of the yield strength vs strain rate. This allowed us to identify the activation energy for high-temperature deformation in flexure as 370 kJ/mol. This level of activation energy is in satisfactory agreement with reports about the diffusion of C in hafnium carbide.

Experimental evidence of the effect of aging on the yielding and pre-yielding behavior of bentonite and laponite suspensions

Thixotropic yield stress materials show a shear-induced solid-liquid transition at the yielding point, characterized by yield stress and yield strain. It is well known in the literature that the elastic modulus and the yield stress of thixotropic materials increase with aging time. In the current work, we propose a discussion on the brittleness of a suspension of swollen bentonite in water, focusing mainly on the role of aging times on the yield strain and on the critical strain at the linear to nonlinear viscoelastic transition of the material. The yield strain was measured in creep and constant shear rate start-up experiments, whereas the linear to nonlinear viscoelastic transition was evaluated from Fourier transforms on transient data in oscillatory shear stress amplitude sweeps. We show that aging increases material brittleness since the yield strain decreases with the resting time. On the other hand, the linear to nonlinear viscoelastic transition strain is surprisingly unaffected by the aging process. Other thixotropic systems were also investigated: 8 and 10 wt. % suspensions of bentonite in water and a 2 wt. % suspension of Laponite® in tap water. These lead to similar observations, showing constant linear to nonlinear viscoelastic strains and decreasing yield strains over increasing aging times. These findings bring relevant information to the intricate open-discussion issue on how to describe the behavior of thixotropic materials below the yield stress.

A Method for Rapid Prediction of Edge Defects in Cold Roll Forming Process

In order to implement rapid prediction of edge defects in the cold roll forming process, a new analytical method based on the mean longitudinal strain of the racks is presented. A cubic spline curve with the parameters of the cumulative chord length is applied to fit the corresponding points and center points of different passes, and fitting curves are obtained. As the cold roll forming is micro-tension forming, the tensions between racks are ignored. Then the mean longitudinal strains between racks are obtained. By comparing the mean longitudinal strain between racks and the yield strain of the material, we can judge whether there are defects at the edges. Finally, the reasonableness of this method is illustrated and validated by an example. With this method, the roll forming effect can be quickly predicted, and the position where a greater longitudinal strain occurred can be determined. In order to prevent the defects, the deformation angles need to be modified when the result is beyond the yield strain. To further prove the correctness of the theory, the results of the analytical method are compared with the ones of the non-linear finite element software ABAQUS. The analytical results have the same trend as the finite element results. This method can provide useful guidance to the actual design process.

Pressure propagation and flow restart in a pipeline filled with a gas pocket separated rheomalaxis elasto-viscoplastic waxy gel

A clogged waxy crude oil pipeline, entails a high pressure to de-structure the gelled oil and resume its normal operation. Our earlier work, which utilized generalized Newtonian fluid based model, demonstrated that the presence of a gas pocket in-between the gel plugs, delays pressure propagation in the downstream gel plug [L. Tikariha, L. Kumar, Pressure propagation and flow restart in the multi-plug gelled pipeline, Journal of Fluid Mechanics. 911 (2021)]. This delay in pressure propagation is effectively utilized for sequential gel degradation. In the present work, we consider gel as a rheomalaxis elasto-viscoplastic (REVP) fluid, capable in predicting flow stoppage and pressure signal stoppage. The governing equations for mass, momentum balance, and phase equation are solved together with the REVP rheology model. The propagation of pressure in a REVP gel-filled pipeline is directly related to the gel material's elastic response. For a REVP gel, the flow-restart in a gelled pipeline depends on the conditional statement γ>γs (i.e. mean gel deformation overcoming the yield strain). In the case of a single gel plug, no-pressure propagation is predicted at intermediate compressibility, whereas pressure propagation without flow restart is predicted at low compressibility. In these cases, the presence of a small gas pocket instigates the gel breakage process, resulting in a flow restart. The gas pocket delays the pressure propagation in the second gel plug, resulting in a pressure gradient higher than yield stress across the first gel plug. The first gel plug, which deforms under a high-pressure gradient, compresses the gas pocket. This results in a larger mean deformation in the first gel plug, and it overcomes the threshold yield strain limit (γs). At strain values larger than yield strain the gel structure breaks, resulting in a lower elastic strength in the first gel plug. The lower elastic gel strength ascertains a lower pressure gradient in the first gel plug, allowing a largely unattenuated pressure to propagate in the second plug. The propagation of unattenuated pressure in the second gel plug results in a pressure gradient higher than the yield stress. This causes sequential gel breakage, resulting in a successful flow restart in a pipeline longer than a critical length. The present study also demonstrates that the pressure propagation and initial transient flow depend on the gel properties (i.e. gel strength and compressibility) and the number and size of gas pockets in the gel. The insights gained from the present work provide a cost-effective solution to mitigate the flow restart problem.

Processing and characterization of W23Mo23V17Cr8Ta7Fe22 and WMoVCrTa refractory high entropy alloys

Refractory high entropy alloys (RHEAs) exhibit high strength, high hardness and stable microstructure over a wide range of temperatures. However, these alloys are also characterized by poor ductility. Total strain to failure of 6.2% at room temperature was observed in equiatomic WMoVCrTa RHEA. Attempts are made to improve the mechanical properties by altering the composition of existing RHEAs. This report presents the results of mechanical properties viz., room and elevated temperature properties of W23Mo23V17Cr8Ta7Fe22 and WMoVCrTa RHEAs fabricated by mechanical alloying followed by vacuum arc melting. Both the arc melted alloys revealed presence of two Body-Centered Cubic (BCC) structured phases along with a small amount of intermetallic phase. The arc melted W23Mo23V17Cr8Ta7Fe22 alloy exhibited compressive yield strength of 1688 MPa and an ultimate strain of 7.3% at room temperature whereas at 1000 °C the corresponding values were 1514 MPa and 10.6%. At 1000 °C the arc melted equiatomic WMoVCrTa alloy exhibited compressive yield strength of 785 MPa and an ultimate strain of 5.7%, whereas at 1200 °C the corresponding values were 941 MPa and 8.3%. Yield stress anomaly was observed for the two alloys at elevated temperatures. Both alloys possess high hardness at room temperature. The two RHEAs appear to be viable materials for high-temperature applications like gas turbine blades, combustion chamber lining, high-temperature coating, nuclear reactor walls, etc., due to their combination of high hardness, high strength and yield strain at elevated temperatures.

Shear testing and analysis of the response of confined masonry walls with centered openings made with innovative sintered insulation shale blocks

The innovative sintered insulation shale (SIS) blocks could use as thermal insulation masonry units to construct the green architecture applying the adaptive construction measures. Above all, the seismic behavior of the wall with an opening should clarify in order to apply in earthquake region. Besides the comparative solid wall, the behavior of typical window-type and door-type walls analyzed under the cyclic lateral loads incorporating with the constant vertical load to achieve the purpose. The main variable of the specimens was the size of the opening. Hence, all the walls were with the same innovative construction measure and geometry parameter. The failure mechanism, energy dissipation, damping ratio, lateral stiffness, deformation and strength capacity conducted according to the record data. Based on the results, the opening caused the weaker masonry parts showing serious damage in wall piers and masonry under the opening, which mainly induced for the lack of restrained condition around the opening. In other words, it changed the failure mechanism. Furthermore, the contribution of RC level bonds and tie-columns to the specimen increased as the opening showing the greater strain than yield strain after the maximum strength, which need to take into account their participation in the lateral resistance calculation. The impact of opening still presented in the decreased lateral stiffness and energy dissipation, smaller ductility and shear strength. The reduced portion would result in the opening wall acting as the weaker part in the SIS masonry structure. In addition, the theoretical equations acquired through Strut-and-Tie method proposed considering the failure mechanism and opening impact. The reduction factors for decreased stiffness and angle of masonry strut, relative stiffness between the RC components and masonry parts applied to conduct the calculation of the maximum strength. Compared with the experimental results, the proposed equations showed enough accurate prediction on the maximum shear resistance.

Effect of Ca(NO3)2 coating on chemical and mechanical properties and bruise susceptibility of Golden Delicious and Red Delicious apples during storage

AbstractEffect of coating with calcium nitrate in three concentrations (0.0, 0.5, and 1.0 wt%) on chemical and mechanical properties, and impact behaviour of two apple cultivars (Golden Delicious (GD) and Red Delicious (RD)) during time (0, 2, and 4 months) was studied. Moisture content, pH, titratable acidity, °Brix, organoleptic properties, modulus of elasticity (E), yield stress, yield strain, and toughness were measured. The effect of impact loads was determined by measuring bruise volume (BV) and bruise susceptibility (BS). The results showed that pH and °Brix significantly increased, while titratable acidity, E, yield strain, toughness, and BV decreased during storage time. As Ca(NO3)2 concentration increased, titratable acidity, E, yield strain and yield stress increased and pH decreased (P < 0.05). Highest and lowest values for °Brix were observed in GD treated with 1.0% Ca(NO3)2 after four months (13.31) and GD treated with 0.5% Ca(NO3)2 at the first day (10.65), respectively. Maximum E was obtained in GD treated with 1.0% Ca(NO3)2 on the first day (2130 kPa) and this sample also showed the lowest BS after four months of storage (2.82 mL J−1), while the uncoated GD had the highest BS on the first day (7.11 mL J−1).

Elastoplastic behavior of the γ-phase in Ni-based single crystal superalloys: A molecular dynamics study considering Re and temperature effect

Recent investigations suggest that the addition of trace Re element has a significant influence (the so-called Re-effect) on the mechanical properties of Ni-based single crystal superalloys. Nevertheless, the mechanisms for this Re-effect at different service temperatures are still unclear. The present work studied the elastoplastic deformation behavior of the γ phase in Ni-based single crystal superalloys by molecular dynamics, with the emphasis on Re-associated mechanisms at a wide range of Re contents (from 0 at.% to 9 at.%) and temperatures (from 300 K to 1100 K). The results indicate that the Re content and temperature have an obvious effect on the elastic modulus of the γ phase, the higher the Re content and temperature, the lower the elastic modulus. The yield stress and strain decrease with the increase of Re content and temperature. Both the temperature and Re content affect the formation and propagation of dislocations, which further leads to a correlation between the evolution of dislocations and stress-strain. In addition, the effects of size and strain rate on elastoplastic behavior are also studied.

Densification of Ceramic Matrix Composite Preforms by Si2N2O Formed by Reaction of Si with SiO2 under High Nitrogen Pressure. Part 2: Materials Properties

Ceramic matrix composites (CMCs) have been prepared and optimized as already described in part I of this paper. The fibrous preform made of Hi-Nicalon S fibers was densified by a matrix composed of Si2N2O prepared inside the CMC by reacting a mixture of Si and SiO2 under high nitrogen pressure. This part describes the oxidation resistance and mechanical properties of the optimized CMC. The CMC submitted to oxidation in wet oxygen at 1400 °C for 170 h exhibited an oxidation gradient from the surface to almost the center of the sample. In the outer part of the sample, Si2N2O, Si3N4 and SiC were oxidized into silica in the cristobalite-crystallized form. The matrix microstructure looks similar to the original one at the center of the sample, while at the surface large pores are observed and the fiber/matrix interphase is consumed by oxidation. The elastic modulus and the hardness measured at room temperature by nano-indentation are, respectively, 100 and 8 GPa. The elastic modulus measured at room temperature by tensile tests ranges from 150 to 160 GPa and the ultimate yield strength from 320 to 390 MPa, which corresponds to a yield strain of about 0.6%. The yield strength identified by acoustic emission is about 40 MPa.

A comparison of rib cortical bone compressive and tensile material properties: Trends with age, sex, and loading rate

The objectives of this study were to develop novel methods for quantifying human rib cortical bone material properties in compression and to compare the compressive material property data to existing tensile data for matched subjects. Cylindrical coupons were obtained from the rib cortical bone of 30 subjects (M = 19, F = 11) ranging from 18 to 95 years of age (Avg. = 48.5 ± 24.3). Two coupons were obtained from each subject. One coupon was tested in compression at 0.005 strain/s, while the other coupon was tested in compression at 0.5 strain/s. Load and displacement data were recorded so that the elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, elastic strain energy density (SED), plastic SED, and total SED could be calculated. All compressive material properties were significantly different between the two loading rates. An ANOVA revealed that sex alone had no significant effect on the compressive material properties. The interaction between sex and age was significant for some material properties, but this may have been a consequence of the lack of older females in the subject pool. None of the compressive material properties were significantly correlated with age, but were more correlated with sample density. This finding differed for the tensile material properties, which showed stronger correlations with age. When comparing between tension and compression, significant differences were observed for all material properties except for the total SED, once the effects of loading rate and age had been accounted for. This was the first study to quantify the material properties of human rib cortical bone in compression. The results of this study demonstrated that rib and thorax finite element models should consider the effects of loading rate, loading mode, and age when incorporating material properties published in the literature.

Novel CT-Based Bone Strength Assessment By Finite Element Analysis for Monitoring Bone Involvement in Myeloma: a Proof of Concept Study

IntroductionMyeloma (MM) is characterized by osteolytic bone disease, detected in up to 80% of patients, increasing the risk for skeletal related events (SREs), causing morbidity, undermining quality of life and impairing survival. Current imaging modalities provide qualitative measures of bone involvement, often after irreversible damage has occurred.Bone strains are a biomechanical measure of bone strength which quantifies bone relative deformation in response to applied force. As a result of load on bone strains develop which may lead to fracture, once strain magnitude reaches the yield strain. Lytic bone lesions cause local weakening expressed by an increase in local strains.We developed CT-based finite element analysis (CTFEA), a novel measure designed to accurately estimate bone strains based on conventional CT scans. We hypothesize this tool may enable quantifying changes in bone strength over time, by monitoring strain. In this concept study we explore the sensitivity and responsiveness of CTFEA in myeloma patients to detect bone-disease progression and treatment response, and explore clinical correlates.MethodsPatients: A pilot retrospective study. After approval by the institutional ethics committee, 16 MM patients, with at least 2 consecutive CT scans including the spine and at least the proximal 1/3 of the femur since 2010 were identified. Demographic, clinical and radiographic data were abstracted from medical records.CTFEA: Femurs of interest were segmented from the CT scan, and a computational model was created with “stiffness” changing from point to point according to CT's gray values. The computational model was loaded virtually with a physiological stance position contact hip force (2.5 X body weight) applied on the femur's head. An elastic finite element analysis was performed that predicts the displacements and strains at any point within the bone (Figure 1). The locations of interest where the larger change in material properties may occur between consecutive CT scans were determined by computing the relative difference in Hounsfield unit (HU) radio-density along bone's axis. At these locations the principal strains were extracted and monitored. A monotonic increase in strains implies deterioration of bone strength, and vice versa. For patients with lytic lesions, bone strength is quantified by monitoring the principal strains in lesions vicinity. Healing is quantified by a decrease in strains. The CTFEA results were compared to conventional radiographic and laboratory measures.ResultsTable 1 summarizes individual patient clinical data at the time points of each of the CT-scans as well as the calculated CTFEA strain values at the location of maximum HU change of the initial 7 patients. Complete analysis of femur and vertebral strain for 16 patients will be presented at the meeting. Indeed no visible change in strain is demonstrated for smoldering MM (SMM) patients (Pts 15 and 16), whereas a monotonic increase is seen for patient 3, RRMM, with successive relapses without visible tumor identified in the femur in CT scans.Patient 17 (RRMM) with a lytic tumor at the distal femur, shows an initial deterioration of bone strength followed by a monotonic improvement until almost full regain of strength after 19 months.Patient 10 (NDMM) with a lytic tumor in the vicinity of the lesser trochanter, achieved a partial response of MM following anti-myeloma induction within 6 weeks, and as well as a significant increase in bone strength. Patient 13 had a rapid MM response but parallel worsening strain in the right femur, patient 18 had a MM partial response over 5 months with slight worsening of strain.ConclusionsPromising trends were found between CTFEA strain prediction and MM clinical course. SMM patients had minimal changes whereas a patient with progressive disease had a monotonic increase in strains. A decrease in strain was seen in some but not all who responded to therapy. The preliminary study is to be enhanced by considering vertebrae, analyzing further patients as well as prospective validation against SREs, to refine calibrate and tailor this measurement. By providing a quantitative metric of bone strain, this tool may allow monitoring bone strength throughout myeloma evolvement, prior to development of SREs. This may support physicians making personalized medical and surgical treatment decisions and provide a useful surrogate endpoint for clinical drug development. [Display omitted] DisclosuresYosibash:PerSimiO: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Trabelsi:PerSimiO: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Microstructural evolution and mechanical properties of AlxCoCrFeNi high-entropy alloys under uniaxial tension: A molecular dynamics simulations study

In this work, the microstructure evolution, deformation mechanism and the mechanical properties of the AlxCoCrFeNi high-entropy alloy (HEAs) under uniaxial tension have been explored using molecular dynamics simulations. The influencing factors including Al concentration, temperature and strain rate have been considered. Results show that the phase transforms from the original single face-centered cubic (FCC) structure into body-centered cubic (BCC), hexagonal close-packed (HCP) and amorphous structure and the atoms with BCC, HCP and amorphous structure increase whereas the atoms with FCC structure decreases with the increase of strain, especially after the yield strain. The increase of both Al concentration and temperature has a negative impact in the tensile properties of AlxCoCrFeNi HEAs including the Young’ modulus, yield stress and yield strain. The dislocation densities decrease whereas the shear strain becomes larger and distributed uniformly with the increase of the temperature. The high Al concentration can inhibit the reduction of Young’s modulus and yield stress with increasing the temperature. In contrast, the increase of strain rate leads to an appreciable hike in the yield stress and yield strain of HEAs but exhibits negligible influence on the Young’s modulus. The high Al concentration can amplify the effect of increasing strain rate on the Young’s modulus and yield stress. The dislocation density does not monotonically change with increasing the strain rate within the considered strain rate range of 108-2 × 1010/s, nonetheless in most cases the dislocation density decreases with increasing strain rate and also temperature.

Yielding Behavior of Bottlebrush and Linear Block Copolymers

Block copolymers can exhibit a pronounced yield stress, but the impact of molecular architecture, chemistry, and self-assembly on macroscopic rheology remains poorly understood. Here, we study the linear-viscoelastic and yield-stress fluid behavior of two architectures—bottlebrush copolymers (with statistical or blocky sequences) and linear diblocks—that self-assemble into body-centered cubic (BCC) spheres and hexagonally close-packed cylinders (HEX). The dynamic properties of these polymers were probed by oscillatory frequency and amplitude sweeps at temperatures well below the order–disorder transition (TODT) to furnish insights into the yielding transition. All BCC-forming polymers have a similar signature of yielding: smaller yield strains (γy,BCC ≈ 0.053 < γy,HEX ≈ 0.18), sharper solid–liquid transitions, and better reversibility than HEX. Statistical bottlebrushes show the most frequency-independent structural modulus (G0) and no signs of defect relaxation. A simple power-law relationship captures the dependence of the normalized structural modulus (G0/RT) on the inter-micelle distance (d) across different architectures and morphologies [G0/(RT) = 1.31 × 104 (nm2.6 mol/m3) d–2.6]. These studies establish quantitative structure–property relationships that are relevant in contemporary applications, for example, extrusion-based 3D printing.