1121 results about "Young's modulus" patented technology

The invention relates to the technical field of robot control, in particular to a force control method and system based on an impedance model for a rope-driven robot. Comprising the steps of system dynamics modeling and parameter identification, real-time axial compression sensing and model updating, Cartesian space impedance model design, adaptive impedance parameter adjustment, inner ring position control based on feedback linearization, force error compensation and expected trajectory generation, real-time control circulation and anti-interference processing and experimental verification and iterative optimization. According to the method, through real-time axial compression sensing and equivalent Young modulus dynamic updating, the problem of model mismatch caused by material rigidity sudden change in the phase change process of the hyperelastic material is solved. Specifically, a traditional method depends on static material parameter calibration, and real-time compensation of the nonlinear characteristic of the material is achieved through online estimation of the axial compression amount of the main beam and iterative correction of the Young modulus.

The invention provides a preparation method of a multi-lithology interbed shale crossing fracturing simulation rock sample, the rock sample and application, and belongs to the technical field of petroleum exploration and development fracturing engineering. The method comprises the following steps: acquiring a same-layer-series interlayer outcrop sample in a target area; mixing and stirring the base materials to prepare a shale rock plate, and cutting the shale rock plate into required thickness; and placing the shale plate and the interlayer outcrop sample in a mold at intervals to prepare a multi-layer mixed rock sample. The prepared rock sample can simulate target layer shale and interlayer tight sandstone and limestone with the Young modulus within 60 GPa, so that the longitudinal lithology heterogeneity of a shale reservoir is accurately represented, and the similarity and reproducibility are high; a large-size true triaxial cross-layer fracturing crack propagation physical simulation experiment under the condition of layered stress loading is carried out, and the influence of main control factors such as the thickness of the interlayer, the Young modulus ratio of the storage interlayer, the stress difference and fracturing process parameters on longitudinal propagation of the cross-layer fracturing crack can be accurately revealed.

The invention discloses a breakable rock-soil granular material triaxial test simulation method based on a lattice spring-discrete element coupling framework, which comprises the following steps: establishing a triaxial test model rectangular boundary condition, and generating a non-breakable spherical rock-soil granular material in the boundary; replacing the generated non-crushable spherical particle material with rock-soil particles considering particle crushing based on a lattice spring-discrete element coupling frame, and assigning parameters; replacing wall bodies on the two sides of the rectangular boundary condition with a large number of bonded spherical particles to generate a flexible membrane boundary; and applying confining pressure to the boundary of the generated flexible membrane, and carrying out shear simulation. According to the method, the Young modulus and the Poisson's ratio can be matched in a high-precision mode, the heterogeneity of elastic response is reduced, strength degradation and friction characteristics are simulated, and the calculation efficiency is greatly improved.

The invention relates to cerium oxide-based polishing powder and a preparation method thereof, a polishing solution and application, the cerium oxide-based polishing powder comprises porous secondary particles assembled by a plurality of primary crystal grains, the primary crystal grain aperture is 2-30 nm, the pore volume is 0.10-0.50 cm < 3 > / g, the specific surface area is 10-80 m < 2 > / g, and the content of surface trivalent cerium accounts for 10-40% of the total surface cerium content. The microstructure of the cerium oxide-based polishing powder is porous cerium oxide-based particles assembled by nano primary particles, and the self-assembly structure enables the cerium oxide-based polishing powder to have higher specific surface area while having higher surface trivalent cerium content, so that higher polishing rate can be obtained; due to the submicron particle size, the dispersity of the polishing slurry is improved; the Young modulus of the polishing powder is reduced due to the porous structure, so that the polishing powder is not easy to break in the polishing process, the surface precision of a polished workpiece is improved, and the service life of the polishing powder is prolonged. Therefore, the cerium oxide-based polishing powder provided by the invention has excellent polishing rate and polishing precision at the same time, and has relatively long service life.

The invention relates to the technical field of crustal stress measurement, in particular to a rock core three-dimensional crustal stress measurement system and method based on multi-source data. The method comprises the following steps: acquiring well wall damage information, and identifying a damage type in the well wall damage information; multiple sections of core samples are selected based on the well wall damage information, and overburden pressure parameters are determined based on the multiple sections of core samples; a rock mechanics experiment is conducted on the rock core sample, rock mechanics parameters are generated, and the rock mechanics parameters comprise the Poisson's ratio, the Young modulus, the uniaxial compressive strength value and the tensile strength value. According to the method, the difference value of the maximum stress and the minimum stress is combined with the multi-source coupling constraint principal stress interval, the intersection points are identified through the topological visualization graph, the numerical range of the maximum principal stress and the minimum principal stress can be accurately determined, and then the information of the three-dimensional crustal stress is obtained.

The invention belongs to the technical field of oil-gas field development, and discloses a continental facies shale volume fracturing process technology optimization method, which comprises the following steps of: calculating a hydraulic fracture complexity index based on a reservoir rock brittleness index, a horizontal stress difference and a natural fracture density; calculating a hydraulic fracture crossing expansion index based on the interlayer interface shear strength, the interlayer stress difference, the vertical stress difference and the tensile strength difference; calculating a multi-cluster hydraulic fracture equilibrium expansion index based on ground stress heterogeneity, fracture toughness heterogeneity and Young modulus; and preferably selecting a continental facies shale volume fracturing process according to the three index evaluation indexes. According to the optimization method for the continental facies shale volume fracturing process technology, the hydraulic fracture complexity index, the hydraulic fracture crossing expansion index and the multi-cluster hydraulic fracture equilibrium expansion index are considered in parallel, an effective process optimization method is provided for continental facies shale volume fracturing, and the improvement volume of continental facies shale fracturing is increased.

The invention discloses an accurate acupuncture positioning method under ultrasonic guidance, which relates to the technical field of medical health and comprises the following steps: acquiring a two-dimensional or three-dimensional ultrasonic image of a target area by utilizing ultrasonic image acquisition equipment; the Young modulus of the target area is calculated by measuring the shear wave propagation speed of the tissue of the target area; a sensor module is adopted to monitor the interaction force between the puncture needle and the tissue in real time, and mechanical data are obtained; according to Young modulus and modulus variance obtained through calculation of the shear wave elastography image and mechanical data fed back by a sensor, a time sequence feature vector is constructed; performing dynamic modeling and prediction on the tissue state in the puncture process by using a long-short-term memory neural network; the path offset of the needle head is judged, a correction signal is generated through a PID controller, and the posture or direction of the needle head is adjusted in real time; the problem of artifacts in a traditional ultrasonic image can be solved, more accurate acupuncture path planning is provided, and the method adapts to the change of tissue elasticity in real time.

The invention discloses a molecular dynamics-macroscopic multi-scale coupling calculation method, which relates to the field of material damage numerical simulation analysis, and comprises the following steps: respectively establishing a microcosmic plate model and a macroscopic plate model; young modulus and Poisson's ratio parameters are calculated through microscale pneumatic simulation in the microcosmic plate model and are transmitted into the macroscopic plate model, a stress value I and a strain value I are obtained through macroscopic pneumatic simulation calculation and are transmitted into the microcosmic plate model, and the stress value I and the strain value I are obtained through microcosmic-macroscopic continuous coupling iteration. And obtaining the mechanical property indexes of the silicon thin plate in each stage from stress starting, crack generation, crack propagation to failure and fracture. The invention provides a molecular dynamics-macroscopic multi-scale coupling calculation method. A new analysis method is provided for researching structural failure and damage in an aerodynamic hot extreme environment through coupling calculation of macroscopic and microscopic scale models.

The invention provides a bolt pre-tightening force loading method and device of a fixed axial force construction device, and relates to the technical field of bolt assembling.According to the bolt pre-tightening force loading method and device, the sound wave propagation time of a bolt is measured through an ultrasonic sensor in the state that stress is not applied, and standard propagation time and related physical parameters are established. And a target pre-tightening force is set, and an initial pre-tightening force is generated according to the target pre-tightening force, so that the bolt is preliminarily fastened. The sound wave propagation time is measured again at the real-time temperature, and the bolt length and the Young modulus are corrected based on the temperature deviation to calculate the real-time stress; and comparing the real-time stress with the target stress to generate a stress deviation index and an adjustment strategy, adjusting the pre-tightening force through the adjustment strategy and an adjustment threshold value, calculating the stress deviation index again for the adjusted pre-tightening force, and ensuring that the adjusted stress deviation index meets the requirement of slightly adjusting the threshold value. According to the method, dynamic monitoring and self-adaptive adjustment of the bolt pre-tightening force are achieved, and the safety of a fixed axial force construction device is improved.

A composite structure for a pressure sensor, a pressure sensor, a method of pressure sensing using the pressure sensor, and a method of fabricating a composite structure for a pressure sensor. The method of fabricating a composite structure for a pressure sensor comprises the steps of forming an array of microstructures made from an elastomeric material; and forming a flexible conductive coating on the array of microstructures such that a surface morphology of microstructures is substantially maintained for the coated array of the microstructures; wherein the conductive coating exhibits a Young's modulus that is higher than that of the elastomeric material.

The invention discloses an MEMS composite film stress gradient measuring device and method. The measuring device comprises a V-shaped thermal actuator structure, a displacement measuring structure connected with the V-shaped thermal actuator structure and a multi-layer cantilever beam structure. The method comprises the steps that a V-shaped thermal actuator structure is used for pushing a displacement measurement structure to move towards a multi-layer cantilever beam structure, and when a contact electrode of the displacement measurement structure makes contact with a to-be-measured beam of the multi-layer cantilever beam structure, a horizontal displacement value s is obtained through reading of the displacement measurement structure; calculating the equivalent stress gradient of the composite film according to the geometric dimension of the measuring device, the horizontal displacement value s and the Young modulus of each layer of film; the MEMS composite film stress gradient measuring device and method have the advantages of being easy to operate, low in cost and high in measuring speed, and can be used for parameter monitoring of a process line.

The invention relates to a defect detection method and system based on multi-modal feature fusion. The method comprises the following steps: acquiring multi-modal data of a transformer; predicting based on the multi-modal data through the fusion prediction model, and outputting an elastic modulus distribution diagram of the insulating material in the transformer; carrying out super-resolution enhancement on the elastic modulus distribution diagram based on a physical constraint diffusion model; and positioning the defects of the transformer through a time reversal algorithm on the basis of the internal Young modulus distribution and the super-resolution elastic modulus distribution diagram of the transformer. According to the invention, the problems of feature loss, large single modal error, fuzzy fractal defect reconstruction, insufficient defect positioning precision and the like caused by signal attenuation in traditional detection are solved. According to the method, the signal-to-noise ratio and modulus distribution prediction precision of the signal is remarkably improved, micron-order super-resolution reconstruction is achieved, winding deformation and insulation layering are accurately distinguished, harm is quantified, traditional imaging limitation is overcome, and a high-precision and physically consistent basis is provided for transformer state evaluation and maintenance.

The invention discloses a meshless EFGM and style migration-based multi-material structure topological optimization method, which comprises the following steps of: (1) inputting material attributes such as Young modulus, shear modulus and Poisson's ratio of a structure, and discretizing a design domain by using meshless nodes; (2) transforming the designed meshless density field to obtain a physical density field, and performing length scale filtering; (3) an alternating active phase algorithm is executed, and the displacement field, the system flexibility and the related sensitivity of the structure are solved based on the meshless EFGM; (4) executing a neural style migration program to calculate the difference between the current topological structure and the reference style image, and calculating the derivative of the physical density field of the topological structure to the network parameter; and (5) updating a design variable by using a moving asymptote algorithm, and judging whether an optimization loop is converged or not. According to the method, based on meshless EFGM and style migration multi-material structure topological optimization, topological structures with different artistic styles can be designed, and the method has engineering application value.

To provide a coated optical fiber in which resistance against high temperature and high humidity of a primary layer having is improved.SOLUTION: A coated optical fiber includes an optical fiber bare wire, a primary layer which coats the optical fiber bare wire and is formed of first ultraviolet curable resin, and a secondary layer which coats the primary layer and is formed of second ultraviolet curable resin. The primary layer has a carbon-sulfur bond, the primary layer includes 0.007 wt.% or more and 0.14 wt.% or less of sulfur atom, Young's modulus of the primary layer is 0.17 MPa or more and 2.24 MPa or less, and an absolute value of variation of Young's modulus of the primary layer when being exposed under the environment of 85°C and humidity of 85% for two days is 0.09 MPa or less.SELECTED DRAWING: Figure 1

To provide an optical glass with excellent formability, high stability during the production process, and excellent color correction over a broad range, as well as an optical element including the optical glass.SOLUTION: An optical glass according to the present invention is characterized in that: the refractive index (nd) at the helium d-line wavelength (587.6 nm) is in the range of 1.45000 to 1.65000; the ISO color characteristic index (ISO / CCI) is 0.00 for blue (B), 0.80 or less for green (G), and 0.80 or less for red (R); and the value of S, derived from the equation S=E α / (1-ν), is within the range of 0.70×106 or more and less than 1.03×106 (Pa / °C), where E denotes Young's modulus (unit: GPa), α denotes the average linear expansion coefficient in the temperature range of 100°C to 300°C (unit: 10-7°C-1), and ν denotes Poisson's ratio.SELECTED DRAWING: None

The invention relates to a brittleness index calculation method and device for a superior paleozoic mud shale stratum. The brittleness index is an arithmetic mean value of an intermediate parameter obtained through Young modulus data and an intermediate parameter obtained through Poisson's ratio data. Wherein the intermediate parameter obtained through the Young modulus data is a normalized value of the Young modulus, and the intermediate parameter obtained through the Poisson's ratio data is a normalized value of the Poisson's ratio. According to the method, multiple linear regression is carried out by using conventional logging data, the shear wave time difference model is constructed to fit the shear wave data, the correlation coefficient between the obtained brittleness index and the rock brittleness index obtained by the array acoustic logging data is high, and the method is suitable for solving the rock brittleness index in the absence of the array acoustic logging data. And calculating the brittleness index of the strong-heterogeneity shale formation aiming at complex mineral components in the paleozoic region.

This packaging material has a structure in which a transparent vapor-deposited barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order. The transparent vapor-deposited barrier film and the stretched nylon film are laminated with an adhesive layer formed of a cured product of a solventless adhesive agent therebetween. The ratio of the Young's modulus in the MD direction of the unstretched polypropylene film with respect to the thickness of the unstretched polypropylene film is 9.0 MPa / μm or more.

The invention discloses a welding thermal stress simulation method, device, equipment and medium based on a crystal plasticity finite element, and relates to the technical field of welding thermal stress finite element simulation. The method comprises the steps that a sample is prepared according to a specific multi-phase metal material, and phase distribution and crystal orientation information of a two-dimensional plane of the material are obtained through a metallographic experiment; and a three-dimensional multi-grain model is constructed based on the two-dimensional information. According to the method, a crystal plastic constitutive model is adopted to describe the flowing behavior of the material at high temperature, crystal slippage and polycrystal interaction are considered, the influence on the material performance is reflected from the microstructure evolution level, and the problem that the influence on the macroscopic mechanical performance of a microstructure is difficult to capture in welding multiphase metal material simulation is solved; two-dimensional representation is obtained through a metallographic experiment, the Young modulus and rigidity matrix parameters are accurately calculated by combining forward stretching and shear simulation, the rigidity matrix precision is improved, a temperature field area is divided, stress evolution and residual stress are calculated by combining a thermal-elastic-plastic model, and the welding thermal stress calculation precision is improved.

The invention provides an aircraft composite material defect simulation method based on finite element analysis, and relates to the technical field of material defect simulation. Comprising the following steps: S1, setting an analysis system which is statics, dynamics or thermal analysis; s2, establishing a geometric model; s3, introducing defects of the composite material into the geometric model; s4, defining material parameters including elastic modulus, density and Young modulus; s5, performing mesh generation on the geometric model, and decomposing the structure into finite elements; s6, setting boundary conditions of the simulation geometric model, wherein the boundary conditions comprise constraints and loads; s7, simulation is operated, and the response of the geometric model under the given loading condition is obtained; s8, analyzing an operation result, and checking defect influence in the structure; compared with the prior art, the influence of composite material defects in an aircraft structure can be accurately simulated, and the performance of the aircraft structure can be improved.

The invention discloses a method for measuring fan blade root stress based on a fiber bragg grating sensor. According to the method, 6-10 key measurement points are selected in a blade root area of a fan blade, a pair of FBG sensors is installed at each measurement point, one FBG sensor is used for stress measurement (affected by strain and temperature at the same time), the other FBG sensor is used for temperature compensation, and decoupling of temperature and strain signals is achieved. The system adopts a single-mode optical fiber, a broadband light source (the wave band is 1525-1565 nm, and the power is 10-20 mW) and a high-resolution spectrum analyzer (the resolution is smaller than or equal to 1 pm, and the sampling rate is larger than or equal to 100 Hz or 1 kHz) to collect optical signals reflected by an FBG sensor in real time, measured wavelength shift is converted into accurate strain data through temperature compensation and a strain calculation formula, and the optical signals are transmitted to the FBG sensor. And calculating a stress value by combining the Young modulus and Poisson's ratio of the material. The method has the advantages of being high in precision, high in real-time performance, resistant to electromagnetic interference and suitable for seaborne, high-altitude and other severe environments, and reliable data support can be provided for dynamic stress monitoring, fatigue life prediction and fault early warning of the fan blade.

To provide a copper alloy excellent in conductivity while having a sufficiently large elastic deformation amount with a low Young's modulus and unlikely to cause a plastic deformation even under a large deformation.SOLUTION: A copper alloy has a composition including 15-57 mass% Zn, 12 mass% or less Al, satisfying A+5×B≥30 and A+3.5×B≤57 in which the Zn content is A mass% and the Al content is B mass%, and a balance Cu with inevitable impurities. A volume fraction in a β phase is 50% or more. an average of KAM (Kernel Average Misorientation) values of the β phase is 2.0° or less obtained when a measurement area of 1 mm2 or more is measured at a measurement interval 1 μm step by an EBSD method and measured excluding a measurement point with a CI value of 0.1 or less analyzed by data analysis software OIM.SELECTED DRAWING: None

The present invention relates to the technical field of oil-gas exploration. Provided are a method and apparatus for determining the minimum horizontal principal stress of a shale oil reservoir. The method comprises: using a shallow resistivity curve to calibrate a conductivity curve, so as to obtain a high-resolution resistivity curve; using oil porosity information to calibrate nuclear-magnetic-resonance-logging data, so as to determine a continuous oil saturation curve; determining a continuous saturation index curve according to elemental capture spectroscopy data and rock electrical-experiment data; determining a high-resolution full-water-saturation resistivity curve according to the high-resolution resistivity curve, the continuous oil saturation curve and the continuous saturation index curve; using a high-resolution static Young's modulus calculation model to determine a high-resolution static Young's modulus; and further determining a continuous minimum horizontal principal stress. The present invention can improve the resolution of the minimum horizontal principal stress of a shale oil reservoir.

To provide a copper alloy excellent in conductivity while having a sufficiently large elastic deformation amount with a low Young's modulus and unlikely to cause a plastic deformation even under a large deformation.SOLUTION: A copper alloy has a composition including 15-57 mass% Zn, 12 mass% or less Al, satisfying A+5×B≥30 and A+3.5×B≤57 in which the Zn content is A mass% and the Al content is B mass%, and a balance Cu with inevitable impurities. A volume fraction in a β phase is 50% or more. When a measurement area of 8 mm2 or more is measured at a measurement interval 8 μm step by an EBSD method and analyzed excluding a measurement point with a CI value of 0.1 or less obtained through an analysis by data analysis software OIM, and an interval between measurement points in which an orientation difference between neighboring measurement points is 5° or more is regarded as a crystal grain boundary, a ratio of each coincidence boundary length of 3≤Σ≤29 to all crystal grain boundary lengths L at which measured β phases are abutting with each other is 4% or more.SELECTED DRAWING: None

The invention discloses an MEMS double-layer film Young modulus measuring device and method, the measuring device comprises three subsections, and each subsection comprises a thermal actuator structure, a displacement measuring structure connected with the thermal actuator structure and a double-layer cantilever beam structure; the method comprises the steps that a thermal actuator structure is used for pushing a displacement measurement structure to move towards a double-layer cantilever beam structure, and when a contact electrode of the displacement measurement structure makes contact with a to-be-measured beam of the double-layer cantilever beam structure, horizontal displacement values s1, s2 and s3 of three subsections are obtained through readings of the displacement measurement structure; the physical dimension and the horizontal displacement values s1, s2 and s3 of the measuring device are substituted into an equation to solve the Young modulus of the double-layer film; the MEMS double-layer film Young modulus measuring device and method have the advantages of being easy to operate, low in cost and high in measuring speed, and can be used for parameter monitoring of a process line.

The invention relates to the field of pressure sensors, in particular to a triboelectric pressure sensor and a sleep monitoring method and system. The triboelectric pressure sensor comprises a positive friction layer, a negative friction layer, a deformation electrode connected to the negative friction layer and a flexible electrode connected to the positive friction layer. The contact ends of the tips of the multiple micro-cone structures of the positive friction layer all face the negative friction layer, and gaps are formed between the contact ends and the negative friction layer. The Young modulus of the negative friction layer is smaller than that of the micro-cone structure, so that when the negative friction layer approaches the deformed electrode, the negative friction layer sinks and makes contact with the side face of the micro-cone structure. The change amplitude of the contact surface along with the pressure is large, so that the sensitivity of the sensor is improved. Respiration and pulse frequencies are respectively detected by a triboelectric pressure sensor to obtain electric signals, the electric signals are segmented and enhanced into waves, then the waves are classified by a big data method, a learning model for identifying sleep state categories corresponding to the waves is obtained, the categories are further rapidly and accurately identified, and an alarm is given according to the number of abnormal times. The method and the system have high reliability.

The present invention provides a ceramic particle (141) and a coating layer (142) that covers at least a part of the surface of the ceramic particle and contains two or more phases. The coating layer contains a first phase (142a) that is composed of an oxide-based ion conductor, and a second phase (142b) that is composed of an amorphous-containing ion conductor which contains an amorphous phase. The first phase has an ionic conductivity which is higher than that of the second phase. The second phase has a Young's modulus which is lower than that of the first phase.

A glass substrate of the present invention has a strain point of from 695° C. to 740° C., a temperature at 104.5 dPa·s of 1,300° C. or less, a liquidus viscosity of 104.5 dPa·s or more, a Young's modulus of 78 GPa or more, and a thermal shrinkage rate in heat treatment at 500° C. for 1 hour of 20 ppm or less.

The invention discloses a method and device for measuring structural parameters of an MEMS cantilever beam, and the method comprises the steps: placing the MEMS cantilever beam on an objective table of a nanoprobe station, and guaranteeing that the thickness direction of the MEMS cantilever beam is perpendicular to a horizontal plane; measuring the length l and the width b of the MEMS cantilever beam by using a microscope; controlling a micro probe of the nano probe station to descend until the micro probe is in contact with the surface of the MEMS cantilever beam; continuously controlling the micro-probe to descend, and recording the displacement X and the loading stress F of the micro-probe at the same time; carrying out linear fitting by utilizing a preset calculation device displacement X and the loading stress F to obtain the deformation rigidity K of the MEMS cantilever beam; and calculating the thickness h of the MEMS cantilever beam based on the deformation stiffness K, the length l, the width b and the Young modulus E. The measuring method is wide in application range and low in testing cost.

The invention belongs to the technical field related to structure optimization design, and discloses a topological optimization method and device for a metamaterial microstructure capable of bearing a band gap, and the method comprises the steps: (1) respectively defining an interpolation penalty coefficient of a Young modulus for the homogenization analysis of the microstructure and the band gap problem of an energy band structure according to the performance analysis of the microstructure, calculating an interpolation penalty coefficient of the mass density; (2) carrying out homogenization analysis of the microstructure based on dynamics to obtain equivalent physical property parameters and determine equivalent material modulus; (3) defining an irreducible first Brillouin region wave vector path of the microstructure based on the geometric symmetry constraint of the microstructure, and further calculating a band gap quality factor between adjacent energy band curves of the microstructure; and (4) establishing a topological optimization model which takes the equivalent modulus as a grading constraint and takes band gap quality factor maximization as a target, and performing iterative optimization based on the topological optimization model to obtain an optimal microstructure configuration. According to the invention, efficient and stable design of the microstructure is realized.

Provided is a glass composition which has a low linear expansion coefficient and a high Young's modulus and is suitable for mass production. The present invention provides, in mass%: i) a glass composition containing 56 < = SiO2 < = 70, 0.1 < = B2O3 < = 8, 15 < = Al2O3 < = 24, 4 < = MgO < = 14, 0 < = CaO < = 4, 0 < = ZnO < = 10, 0 < = (Li2O + Na2O + K2O) < = 4, 0.1 < = ZrO2 < = 5, and substantially not containing TiO2; the present invention relates to a glass composition comprising (i) a glass composition containing 56 < = SiO2 < = 70, 0.1 < = B2O3 < = 8, 15 < = Al2O3 < = 24, 4 < = MgO < = 14, 0 < = CaO < = 4, 0.1 < = ZnO < = 3, 0 < = (Li2O + Na2O + K2O) < = 4, and substantially not containing TiO2 and ZrO2, and iii) a glass composition containing 56 < = SiO2 < = 70, 0.1 < = B2O3 < = 8, 15 < = Al2O3 < = 24, 4 < = MgO < = 14, 0 < = CaO < = 4, 0 < = ZnO < = 10, 0 < = (Li2O + Na2O + K2O) < = 4, and 1 < = ZrO2 < = 5.