Mathematical model of deformation resistance of 30 MnSi V steel

Based on 30MnSiV steel, the deformation resistance was studied by using Gleeble 1500 thermomechanical simulator. The mathematical model of the deformation resistance is established by analyzing the relationship of the deformation temperature, deformation rate and deformation resistance. The regression equation is highly noticeable by means of regression analysis. The mathematical model corresponds to test data by means of the contrast.

Deformation resistance prediction of tandem cold rolling based on grey wolf optimization and support vector regression

In the traditional rolling force model of tandem cold rolling mills,the calculation of the deformation resistance of the strip head does not consider the actual size and mechanical properties of the incoming material,which results in a mismatch between the deformation resistance setting and the actual state of the incoming material and thus affects the accuracy of the rolling force during the low-speed rolling process of the strip head.The inverse calculation of deformation resistance was derived to obtain the actual deformation resistance of the strip head in the tandem cold rolling process,and the actual process parameters of the strip in the hot and cold rolling processes were integrated to create the cross-process dataset as the basis to establish the support vector regression(SVR)model.The grey wolf optimization(GWO)algorithm was used to optimize the hyperparameters in the SVR model,and a deformation resistance prediction model based on GWO–SVR was established.Compared with the traditional model,the GWO–SVR model shows different degrees of improvement in each stand,with significant improvement in stands S3–S5.The prediction results of the GWO–SVR model were applied to calculate the head rolling setting of a 1420 mm tandem rolling mill.The head rolling force had a similar degree of improvement in accuracy to the deformation resistance,and the phenomenon of low head rolling force setting from stands S3 to S5 was obviously improved.Meanwhile,the thickness quality and shape quality of the strip head were improved accordingly,and the application results were consistent with expectations.

Numerical simulation of rockburst disaster and control strategy of constant resistance and large deformation anchor cable in Gaoloushan tunnel

The Gaoloushan Tunnel in Longnan City,Gansu Province,China,frequently experiences rockburst disasters due to high in-situ stress.Managing rockburst in deep-buried tunnels remains a challenging issue.This paper employs RFPA(Rock Failure Process Analysis)software to establish a calculation model of constant resistance and large deformation(CRLD)anchorages and analyzes the effects of different support methods and pre-stress levels on rockburst.We simulate the process of tunnel rockburst disasters and find that ordinary anchor support incurs rockburst on the right arch waist and arch top,forming a V-shaped explosion pit.CRLD anchor support has several advantages in rockburst control,such as more uniform stress distribution in the surrounding rock,a uniform distribution of plastic zones,less noticeable damage to the tunnel,and effective control of the arch top displacement.The effectiveness of the CRLD anchor support under varying pre-stress conditions shows that a higher prestress results in a smaller plastic zone of the surrounding rock and arch top displacement and a lower number of acoustic emission signals,which better explains the excavation compensation effect.Moreover,adding long anchorages in the deep surrounding rock area can better control rockburst and reduce surrounding rock deformation.Based on these findings,we propose a comprehensive control system that combines long and short anchorages and provides the optimal scheme based on calculations.Therefore,by using high-prestress CRLD anchor support and the combination of long and short anchorages at critical positions,we can enhance the integrity of the surrounding rock,effectively absorb the energy released by the surrounding rock deformation,and reduce the incidence of rockburst disasters.

Deformation resistance of Fe-Mn-V-N alloy under different deformation processes

The deformation resistance of Fe-Mn-V-N alloy under different deformation conditions was investigated by hot compression method on thermal simulator.Effects of deformation degree, deformation temperature,and strain rate on deformation resistance were analyzed.The results show that when other conditions are constant,the deformation resistance increases with the increase in deformation degree and strain rate and decreases with the increase in deformation temperature. At the same time, the mathematical model of deformation resistance for Fe-MnV-N alloy was established by 1 stOpt software using the Levenberg-Marquardt optimization algorithm carried out on the fitting of regression coefficients, which has higher fitting precision.

Modeling deformation resistance for hot rolling based on generalized additive model

A model of deformation resistance during hot strip rolling was established based on generalized additive model.Firstly,a data modeling method based on generalized additive model was given.It included the selection of dependent variable and independent variables of the model,the link function of dependent variable and smoothing functional form of each independent variable,estimating process of the link function and smooth functions,and the last model modification.Then,the practical modeling test was carried out based on a large amount of hot rolling process data.An integrated variable was proposed to reflect the effects of different chemical compositions such as carbon,silicon,manganese,nickel,chromium,niobium,etc.The integrated chemical composition,strain,strain rate and rolling temperature were selected as independent variables and the cubic spline as the smooth function for them.The modeling process of deformation resistance was realized by SAS software,and the influence curves of the independent variables on deformation resistance were obtained by local scoring algorithm.Some interesting phenomena were found,for example,there is a critical value of strain rate,and the deformation resistance increases before this value and then decreases.The results confirm that the new model has higher prediction accuracy than traditional ones and is suitable for carbon steel,microalloyed steel,alloyed steel and other steel grades.

High-Temperature Deformation and Low-Temperature Fracture Behavior of Steel Slag Rubber Asphalt Mixture Surface Layer

Steel slag is regarded as one of the most widespread solid by-products of steel smelting with little commercial value.It can play a vital role in the construction industry especially in the field of transportation infrastructure construction.However,there are few evaluation systems established on the high-temperature deformation and low-temperature fracture behavior of steel slag rubber asphalt mixture(SSRAM).This study explores the perfor-mance of SSRAM by uniaxial penetration test,Semi-Circular Bending(SCB)test and evaluates test data through regression analysis.The uniaxial penetration test results shows that the failure deformation of SSRAM increases with the increase of steel slag content.According to the minimum allowable permanent deformation(R TS-min),the deformation of SSRAM should be controlled within 3 mm.Meanwhile,the cracking index of the SSRAM surface layer calculated at low temperature can meet the design requirements.The SCB test results show that the stress peak degradation rate(specimens with 10 mm notch are compared with 0 mm)of SSRAM with 40%steel slag content is 20.04%.That means proper steel slag content makes the stress peak degradation rate of SSRAM reaches the lowest value.The calculation results of fracture energy density(J_(1C))show that the steel slag additive reduced the fracture energy density of SSRAM.However,it is still proved that SSRAM with 40%steel slag has the best low-temperature fracture performance based on critical fracture toughness(K_(1C))and fracture stress peak.Further-more,the crack propagation velocity parametric equation of SSRAM is proposed through fracture mechanics theory and the increase of velocity is exponential.Considering the high-temperature deformation resistance and low-temperature fracture property,the SSRAM surface layer with 40%steel slag content showed a batter application potential.

Effects of Filler-Asphalt Ratio on the Properties of Lignin and Polyester Fiber Reinforced SMPU/SBS Modified Asphalt Mortar

To understand the effects offiller-asphalt ratio on different properties of lignin and polyesterfiber reinforced shape memory polyurethane(SMPU)/styrene butadiene styrene(SBS)composite modified asphalt mortar(PSAM),as well as to reveal the reinforcing and toughening mechanisms of lignin and polyesterfibers on PSAM,SMPU,SBS and mineral powder werefirst utilized to prepare PSAM.Then the conventional,rheological and anti-cracking properties of ligninfiber reinforced PSAM(LFAM)and polyesterfiber reinforced PSAM(PFAM)at dif-ferentfiller-asphalt ratios were characterized.Test results indicate that the shear strength,deformation resistance and viscosity are increased after adding 0.8wt%ligninfiber or polyesterfiber and increasing thefiller-asphalt ratio from 0.8 to 1.2.The optimalfiller-asphalt ratio of 1.0 is proposed after comprehensive performance assessments of PSAM.Polyesterfiber shows a better reinforcing effect than ligninfiber,but its improvement in the thermal stability of PSAM is not significant at high temperatures.Additionally,the complex modulus,storage modulus,loss modulus and rutting resistance factor of PSAM are improved after adding ligninfiber and polyesterfiber,as well as show an increasing trend as thefiller-asphalt ratio is raised,but the phase angle is gradually decreased.Further,the increase of elastic components in PSAM effectively enhances the anti-deformation ability of PSAM at high temperatures,and polyesterfiber more obviously improves the high-temperature deformation resistance of PSAM than ligninfiber.Finally,the anti-cracking performance of PFAM and LFAM at low temperatures is reduced by 74.2%and 46.7%,respectively,as thefiller-asphalt ratio is raised from 0.8 to 1.2.The low-temperature anti-cracking performance of LFAM is lower than that of PFAM at the samefiller-asphalt ratio,even lower than that of PSA.Compared with ligninfiber,the anti-cracking performance and deformation resistance of PSAM at low temperature is more greatly enhanced by polyester fiber.

Classification of inelastic deformation and material-intrinsic indices about mechanical performance of general solid matter

The present article is aimed to detect material-intrinsic indices that can be used to supervise the mechanical performance of general solid matter.The novelty carried in this article can be summarised as follows.Firstly,an inelastic deformation state of almost any solid matter can be treated as the combination of two fundamental modes due to different microscopic causation:Mode I inelastic distortion due to the movement of sliding types of defects and Mode II inelastic dilation due to the evolution of voids/bubbles.Secondly,each inelastic deformation mode is characterised by a single principal inelastic deformation descriptor(PIDD):Mode I by a newly introduced quantity of maximum distortional angle changeαand Mode II by the logarithm of dilating magnificationω.In particular,the concept of maximum distortional angle change gives rise to a geometrically intuitive yield criterion ofα>α_(c),which in situations of small deformation,is shown to asymptote von Mise's,and to become Tresca's in cases of plane stress.Thirdly,the deformation process of a solid matter under monotonic and ambient loads is formulated by means of trajectories of thermodynamic equilibria with respect to the PIDD pair.Then a pair of physical quantities which measure the stresses needed to change the local PIDD state are singled out.Being termed as inelastic deformation resistances(IDRs),these two quantities are shown to depend only on the onsite atomic configurations.It is also shown that key descriptive properties about the mechanical behaviours of materials,such as ductility,are encoded in IDRs as functions of PIDDs.Hence the IDR pair may serve as material performance indices that may be more intrinsic than conventional stress-strain relationships.

Designing multilayer diamond like carbon coatings for improved mechanical properties

New multilayer coatings were produced by incorporating alternating soft and hard DLC layers enabled by varying the bias voltage during deposition process while maintaining a constant hard-to-soft layer thickness ratio.These coatings were deposited onto a Cr/Cr Cxgraded layer by closed field unbalanced magnetron sputtering(CFUBMS).The cross-sectional analysis of the coatings showed that the multilayer coatings possess sharp interfaces between the soft and hard layers with the hard to soft layer thickness ratio(1:1.33)constant in all the coatings.Raman analysis uncovered the increasing sp^(3)character of the DLC coatings as a result of decreasing ID/IGratio and increasing full width at half maximum(FWHM)values of the G band peak induced supposedly by an increase in bias voltage during hard layer deposition.Nanoindentation tests showed an increase in hardness of the DLC coatings which can be correlated with the increase in the sp^(3)content of the coatings as well as decreasing sp^(2)-C cluster size,as calculated from the ID/IGratio.Furthermore,the coatings exhibited excellent plastic deformation resistance and adhesion strength upon microindentation and scratch testing,respectively.Although further investigations are required to assess coating durability,the multilayer design could offer the DLC coatings with a rare opportunity to combine the high hardness with damage resistance with a constant bilayer thickness and without the need to introduce complex multilayer system.

A precipitate-free AlCoFeNi eutectic high-entropy alloy with strong strain hardening

Over recent years,eutectic high-entropy alloys(EHEAs)have intrigued substantial research enthusiasms due to their good castability as well as balanced strength-ductility synergy.In this study,a bulk cast Al_(19.25)Co_(18.86)Fe_(18.36)Ni_(43.53)EHEA is developed with fine in-situ lamellar eutectics.The eutectics comprise alternating ordered face-centered-cubic(L1_(2))and ordered body-centered-cubic(B2)phases with semicoherent interfaces.The resulting microstructure resembles that of most reported as-cast EHEAs,but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition.Surprisingly,the B2 lamellae still feature much higher deformation resistance than the L1_(2) lamellae,so that less lattice defects are detected in the B2 lamellae until the fracture.More interestingly,in the L1_(2) lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension.The precipitate-free EHEA consequently shows excellent tensile ductility of~10%and high ultimate strength up to~956 MPa.

Tribological properties of multilayer tetrahedral amorphous carbon coatings deposited by filtered cathodic vacuum arc deposition

Tetrahedral amorphous carbon(ta‐C)has emerged as an excellent coating material for improving the reliability of application components under high normal loads.Herein,we present the results of our investigations regarding the mechanical and tribological properties of a 2‐μm‐thick multilayer ta‐C coating on high‐speed steel substrates.Multilayers composed of alternating soft and hard layers are fabricated using filtered a cathodic vacuum arc with alternating substrate bias voltages(0 and 100 V or 0 and 150 V).The thickness ratio is discovered to be 1:3 for the sp2‐rich and sp3‐rich layers.The results show that the hardness and elastic modulus of the multilayer ta‐C coatings increase with the sp3 content of the hard layer.The hardness reached approximately 37 GPa,whereas an improved toughness and a higher adhesion strength(>29 N)are obtained.The friction performance(μ=0.07)of the multilayer coating is similar to that of the single layer ta‐C thick coating,but the wear rate(0.13×10^(–6) mm^(3)/(N∙m))improved under a high load of 30 N.We further demonstrate the importance of the multilayer structure in suppressing crack propagation and increasing the resistance to plastic deformation(H3/E2)ratio.