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15,106
result(s) for
"Formability"
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Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels
The usage of high-strength steels for structural components and reinforcement parts is inevitable for modern car-body manufacture in reaching lightweight design as well as increasing passive safety. Depending on their microstructure these steels show differing damage mechanisms and various mechanical properties which cannot be classified comprehensively via classical uniaxial tensile testing. In this research, damage initiation, evolution and final material failure are characterized for commercially produced complex-phase (CP) and dual-phase (DP) steels in a strength range between 600 and 1000 MPa. Based on these investigations CP steels with their homogeneous microstructure are characterized as damage tolerant and hence less edge-crack sensitive than DP steels. As final fracture occurs after a combination of ductile damage evolution and local shear band localization in ferrite grains at a characteristic thickness strain, this strain measure is introduced as a new parameter for local formability. In terms of global formability DP steels display advantages because of their microstructural composition of soft ferrite matrix including hard martensite particles. Combining true uniform elongation as a measure for global formability with the true thickness strain at fracture for local formability the mechanical material response can be assessed on basis of uniaxial tensile testing incorporating all microstructural characteristics on a macroscopic scale. Based on these findings a new classification scheme for the recently developed high-strength multiphase steels with significantly better formability resulting of complex underlying microstructures is introduced. The scheme overcomes the steel designations using microstructural concepts, which provide no information about design and production properties.
Journal Article
The Effects of Self-interacting Bosonic Dark Matter on Neutron Star Properties
We propose a model of asymmetric bosonic dark matter (DM) with self-repulsion. By adopting the two-fluid formalism, we study different DM distribution regimes, either, fully condensed inside the core of a star, or, otherwise, distributed in a dilute halo around a neutron star (NS). We show that for a given total gravitational mass, DM condensed in a core leads to a smaller radius and tidal deformability compared to a pure baryonic star. This effect may be interpreted as an effective softening of the equation of state. On the other hand, the presence of a DM halo increases the tidal deformability and total gravitational mass. As a result, an accumulated DM inside compact stars could mimic an apparent softening/stiffening of strongly interacting matter EoS and constraints we impose on it at high densities. We limit the model parameter space by confronting the cross section of the DM self-interaction to the constraint extracted from the analysis of the Bullet Cluster. Furthermore, from the analysis of the effect of DM particles, interaction strength, and relative DM fractions inside NSs we obtained a rigorous constraint on model parameters. To identify its impact on NSs we consider the DM fraction may reach up to 5%, which could be considered too high in several scenarios. Finally, we discuss several pieces of smoking gun evidence of the presence of DM that is free from the abovementioned degeneracy between the effect of DM and properties of strongly interacting matter. These signals could be probed with future and ongoing astrophysical and gravitational wave surveys.
Journal Article
Modeling roll contact curves
Roller devices equipped with deformable coatings are crucial for various mechanical operations in material processing. Understanding the contact lines between these rollers and deformable coatings is essential for revealing physical phenomena in roller devices. This study derives analytical expressions for contact curves based on the physical phenomena in the deformation zone. It has been established that the factor that most influences the mathematical model of the contact curve of the rolls is the ratio of the deformation rates of the roll coating to the deformation rate of the processed material during compression.
Journal Article
Deformation strategy of deformable mirrors for a typical zooming system
This paper presents a deformation strategy of deformable mirrors (DMs) for a typical zoom system. This deformation strategy provides a design method for the surface profile of zooming. It consists of mathematical model of zoom surface profile and the designing of zooming surface profiles loaded on each DM. The simulation experiments and image aberrations analysis are discussed to verify the reliability of the deformation strategy. The experimental results show that the proposed strategy exhibiting a zoom ratio of 2.0×.
Journal Article
Bayesian Model Selection of Neutron Star Equations of State Using Multi-messenger Observations
The measurement of the macroscopic properties of a neutron star, whether in binary or in an isolated system, provides us with a key opportunity to place a stringent constraint on its equation of state. In this paper, we perform Bayesian model selection on a wide variety of neutron star equations of state using multi-messenger observations. In particular, (i) we use the mass and tidal deformability measurements from two binary neutron star merger events, GW170817 and GW190425; and (ii) we use the simultaneous mass–radius measurements of PSR J0030+0451 and PSR J0740+6620 by the NICER collaboration, while the latter has been analyzed by the joint NICER/radio/XMM-Newton collaboration. Among the 31 equations of state considered in this analysis, we are able to rule out different variants of the MS1 family, SKI5, H4, and WFF1 decisively, which are either extremely stiff or soft equations of state. The most preferred equation of state model turns out to be AP3 (or MPA1), which predicts the radius and dimensionless tidal deformability of a 1.4 M ⊙ neutron star to be 12.10 (12.50) km and 393 (513), respectively.
Journal Article
4D printed hydrogel scaffold with swelling-stiffening properties and programmable deformation for minimally invasive implantation
The power of three-dimensional printing in designing personalized scaffolds with precise dimensions and properties is well-known. However, minimally invasive implantation of complex scaffolds is still challenging. Here, we develop amphiphilic dynamic thermoset polyurethanes catering for multi-material four-dimensional printing to fabricate supportive scaffolds with body temperature-triggered shape memory and water-triggered programmable deformation. Shape memory effect enables the two-dimensional printed pattern to be fixed into temporary one-dimensional shape, facilitating transcatheter delivery. Upon implantation, the body temperature triggers shape recovery of the one-dimensional shape to its original two-dimensional pattern. After swelling, the hydrated pattern undergoes programmable morphing into the desired three-dimensional structure because of swelling mismatch. The structure exhibits unusual soft-to-stiff transition due to the water-driven microphase separation formed between hydrophilic and hydrophobic chain segments. The integration of shape memory, programmable deformability, and swelling-stiffening properties makes the developed dynamic thermoset polyurethanes promising supportive void-filling scaffold materials for minimally invasive implantation.
3D printing has potential in designing personalised scaffolds, but minimally invasive implantation is still challenging. Here, the authors report the development of a polyurethane material with temperature triggered shape memory and water triggered deformation that allows for transcatheter delivery.
Journal Article
On the Sound Speed in Neutron Stars
Determining the sound speed c s in compact stars is an important open question with numerous implications on the behavior of matter at large densities and hence on gravitational-wave emission from neutron stars. To this scope, we construct more than 107 equations of state (EOSs) with continuous sound speed and build more than 108 nonrotating stellar models consistent not only with nuclear theory and perturbative QCD, but also with astronomical observations. In this way, we find that EOSs with subconformal sound speeds, i.e., with cs2<1/3 within the stars, are possible in principle but very unlikely in practice, being only 0.03% of our sample. Hence, it is natural to expect that cs2>1/3 somewhere in the stellar interior. Using our large sample, we obtain estimates at 95% credibility of neutron-star radii for representative stars with 1.4 and 2.0 solar masses, R1.4=12.42−0.99+0.52km , R2.0=12.12−1.23+1.11km , and for the binary tidal deformability of the GW170817 event, Λ˜1.186=485−211+225 . Interestingly, our lower bounds on the radii are in very good agreement with the prediction derived from very different arguments, namely, the threshold mass. Finally, we provide simple analytic expressions to determine the minimum and maximum values of Λ˜ as a function of the chirp mass.
Journal Article
Structure deformation and curvature sensing of PIEZO1 in lipid membranes
PIEZO channels respond to piconewton-scale forces to mediate critical physiological and pathophysiological processes
1
–
5
. Detergent-solubilized PIEZO channels form bowl-shaped trimers comprising a central ion-conducting pore with an extracellular cap and three curved and non-planar blades with intracellular beams
6
–
10
, which may undergo force-induced deformation within lipid membranes
11
. However, the structures and mechanisms underlying the gating dynamics of PIEZO channels in lipid membranes remain unresolved. Here we determine the curved and flattened structures of PIEZO1 reconstituted in liposome vesicles, directly visualizing the substantial deformability of the PIEZO1–lipid bilayer system and an in-plane areal expansion of approximately 300 nm
2
in the flattened structure. The curved structure of PIEZO1 resembles the structure determined from detergent micelles, but has numerous bound phospholipids. By contrast, the flattened structure exhibits membrane tension-induced flattening of the blade, bending of the beam and detaching and rotating of the cap, which could collectively lead to gating of the ion-conducting pathway. On the basis of the measured in-plane membrane area expansion and stiffness constant of PIEZO1 (ref.
11
), we calculate a half maximal activation tension of about 1.9 pN nm
−1
, matching experimentally measured values. Thus, our studies provide a fundamental understanding of how the notable deformability and structural rearrangement of PIEZO1 achieve exquisite mechanosensitivity and unique curvature-based gating in lipid membranes.
Cryo-electron microscopy structures of PIEZO1 in liposome vesicles in curved and flattened conformations demonstrate the high deformability underlying the high mechanosensitivity and ion selectivity of PIEZO channel gating.
Journal Article
Bayesian Analysis of Neutron-star Properties with Parameterized Equations of State: The Role of the Likelihood Functions
We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state (EOS) of neutron stars employing either variable- or constant-likelihood functions. The former has the advantage of retaining the full information on the distributions of the measurements, making exhaustive usage of the data. The latter, on the other hand, has the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound speed parameterization method so as to satisfy the constraints from X-ray and gravitational waves observations, as well as those from chiral effective theory and perturbative quantum chromodynamics. In all cases, the two approaches lead to very similar results and the 90% confidence levels essentially overlap. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff on the binary tidal deformability Λ˜≤720 set in the constant-likelihood approach. Our analysis has also produced two additional results. First, an inverse correlation between the normalized central number density, n c,TOV/n s , and the radius of a maximally massive star, R TOV. Second, and most importantly, it has confirmed the relation between the chirp mass and the binary tidal deformability. The importance of this result is that it relates chirp , which is measured very accurately, and Λ˜ , which contains important information on the EOS. Hence, when chirp is measured in future detections, our relation can be used to set tight constraints on Λ˜ .
Journal Article