Material Law Research Articles

Towards the mechanical characterisation of unruptured intracranial aneurysms: Numerical modelling of interactions between a deformation device and the aneurysm wall

Intracranial aneurysm is a critical pathology related to the arterial wall deterioration. This work is an essential aspect of a large scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool regarding the rupture risk assessment. A machine learning algorithm links the aneurysm shape observed and a database of UIA clinical images associated with in vivo wall mechanical properties and rupture characterisation. The database constitution is derived from a device prototype coupled with medical imaging. It provides the mechanical characterisation of the aneurysm from the wall deformation obtained by inverse analysis based on the variation of luminal volume. Before performing in vivo tests of the device on small animals, a numerical model was built to quantify the device’s impact on the aneurysm wall under natural blood flow conditions. As the clinician will never be able to precisely situate the device, several locations were considered. In preparation for the inverse analysis procedure, artery material laws of increasing complexity were studied (linear elastic, hyper elastic Fung-like).Considering all the device locations and material laws, the device induced relative displacements to the Systole peak (worst case scenario with the highest mechanical stimulus linked to the blood flow) ranging from 375 μm to 1.28 mm. The variation of luminal volume associated with the displacements was between 0.95 % and 4.3 % compared to the initial Systole volume of the aneurysm. Significant increase of the relative displacements and volume variations were found with the study of different cardiac cycle moments between the blood flow alone and the device application. For forthcoming animal model studies, Spectral Photon CT Counting, with a minimum spatial resolution of 250 μm, was selected as the clinical imaging technique. Based on this preliminary study, the displacements and associated volume variations (baseline for inverse analyse), should be observable and exploitable.

Assumed strain methods in micromechanics, laminate composite voxels and level sets

AbstractThis work deals with the composite voxel method, which—in its original form—furnishes voxels containing more than one material with a surrogate material law accounting for the heterogeneity in the voxel. We show that the laminate composite voxel technique naturally arises as an assumed strain method, that is, the general framework introduced by Simo‐Rifai, for a specific choice of enhanced strain field. As a consequence, laminate composite voxels may be regarded as a kinematic assumption within a discretization scheme rather than a part of material modeling, as suggested originally. We discuss how to seamlessly integrate composite voxels into the framework of a level‐set description of the microstructure, in particular the accurate and efficient computation of normals and cut‐volume fractions. In contrast to more traditional strategies based on subvoxelizations, the introduced method avoids systematic errors when computing composite voxel properties. We demonstrate the applicability of the developed technology for a number of relevant computational examples.

Nonlinear Semi-Numeric and Finite Element Analysis of Three-Point Bending Tests of Notched Polymer Fiber-Reinforced Concrete Prisms

A nonlinear semi-numeric and finite element analysis of three-point bending tests of notched polymer fiber-reinforced concrete prisms was performed. The computational and experimental results were compared in terms of the load-displacement behavior. The vertical midspan displacement and the crack mouth opening displacement results were considered. The nonlinear semi-numeric computational procedure involved the moment-curvature relation, calculated by considering the constitutive material law from the fib Model Code for Concrete Structures 2010, and considered a plastic hinge mechanism to simulate the cracked region behavior. Two sets of tensile mechanical properties were considered for the constitutive material law: back-calculated (by an inverse analysis) tensile strength properties from the experimental results, and tensile strength properties calculated by simplified expressions from the fib Model Code for Concrete Structures 2010. Other mechanical properties were determined by additional compressive tests and standard relations for the dependency of various mechanical properties on the concrete compressive strength. The nonlinear finite element analysis incorporated the Menetrey-Willam material model to simulate the fiber-reinforced concrete behavior. The nonlinear semi-numeric analysis load-displacement results based on the back-calculated tensile strength properties relatively accurately matched with the experimental results, whereas the nonlinear semi-numeric analysis load-displacement results based on tensile strength properties calculated by simplified expressions from the fib Model Code for Concrete Structures 2010 and the nonlinear finite element analysis load-displacement results showed certain shortcomings.

Radial Displacements in a Rotating Disc of Uniform Thickness Made of Functionally Graded Material

The finite element method is used to calculate a rotating disc, which has a uniform thickness and is made of functionally graded materials, based on the concepts of multilayer disc and equivalent material. These concepts are also available for analytical calculus. The multilayered disc concept perceives the disc as constructed from several layers, and the equivalent material concept regards the disc material as composed of homogeneous and isotropic material but with fictitious properties equivalent in behavior to the functionally graded material. These two concepts, encompassed in this study, allow us to contemplate the variation according to the material law and Poisson's ratio, which is often neglected, to reduce the mathematical complexity. The concepts, models, and methods involved in this study were validated by employing numerical and analytical calculations. The proposed method introduced simplicity, precision, and accessibility to solve the complex problem of functionally graded structures. The calculus development, model validation, and result analysis were based on numerical calculus using the finite element method. The utilized models were grounded on the existence of an axial-symmetric plane. So, 2D or 3D simplified models can be used with several variants regarding the mesh fineness. This study results and models are useful to specialists and structure designers of this type, have a high degree of generality, and present opportunities for the application of other calculation methods.

Use of effective multiscale cohesive models in the simulation of spall in metal plates

AbstractDuctile fracture of metals is the net result of void nucleation, growth and coalescence mechanisms that operate at the microscale. Optimal scaling analysis provides the analytical form of the effective material law that models the ductile fracture phenomena at the macroscale. The upscaled model of ductile behavior assumes the form of a cohesive relation—surface traction versus displacement—of the power‐law type with well‐defined exponents. In the present work, we demonstrate how the effective cohesive law derived from optimal scaling can be conveniently inserted into macroscale calculations by recourse to cohesive elements. The plastic deformation outside the cohesive elements is of moderate size and can be modeled by means of conventional plasticity models. In particular, the mesh size is dictated by accuracy considerations at the macroscale structural level and is not in any way constrained by microscale features and mechanisms, which happen at the subgrid level and are accounted for by the effective cohesive law. We illustrate the multiscale paradigm by means of spall calculations.

Study on multi-objective matching ratio optimization and strength development law of basalt stone powder composite cementitious materials

In order to better apply basalt powder to supplement cementitious materials ( SCMs), this paper chooses the content of basalt powder, fly ash and slag as the influencing factors, and the early strength ( 3d, 7d) and long-term strength ( 28d, 60d) of mortar as the evaluation index of SCMs. Based on the response surface and multi-objective optimization method, the Box-Benken experimental design method was used to study the influence of physical and chemical superposition between various factors on the strength development and optimize the ratio.The low-field nuclear magnetic resonance technique was used to detect the water change and porosity difference between the reference group and the optimization group at each age. The results show that the content of stone powder and fly ash has a significant effect on the early and long-term strength, the slag only has a significant effect on the early strength, the interaction between the three has no significant effect on the early and 60 d strength, and the interaction between stone powder and slag has a significant effect on the 28 d strength. The optimal compatibility of basalt stone powder-assisted cementitious materials is stone powder ( 10%), fly ash ( 5%), and slag ( 25.11%). Under this mix ratio, the strength activity index of mortar at each age meets the requirements. In the early hydration process, the physical filling effect of supplement cementitious materials such as stone powder in the optimization group can better optimize the pore structure inside the slurry, and the strength improvement is slower than that of the reference group. In the later stage of hydration, the number of hydration products in the optimized group increased, and the strength increased significantly, which was closer to the strength of the benchmark group.

Inconsistencies in The Application of Criminal Sanctions for Illegal Use of Plantation Land Based on the Plantation Law

Background: The use of oil palm plantation land provides great potential for national economic income but it cannot be separated from legal problems such as illegal use of plantation land. This is due to overlapping regulations. This study aims to examine the policy of illegal use of plantation land and the application of criminal sanctions for perpetrators of illegal use of plantation land.
 
 Method: This study uses a normative legal approach. Data used by inventing material laws on plantation land use policies and plantation land use sanctions.
 
 Results: The results of this study show that there are overlapping regulations on the illegal use of plantation land.
 
 Conclusion: The importance of consistency in the application of criminal sanctions in general without exceptions to perpetrators of illegal use of plantation land. By harmonizing criminal sanctions in Article 107 of the Plantation Law, it can avoid inconsistencies and unbalanced policies.

CRIMINAL LIABILITY AGAINST PERSONS OF AUTHENTIC DEED FORGERY (Study Decision Number: 1611/Pid.B/2014/Pn.Mks)

This research aims to (1) determine and analyze the forms of criminal responsibility and legal considerations of judges regarding the forgery of authentic deeds based on false statements in Makassar District Court Decision Number: 1611/Pid.B/2014/PN.Mks. (2) knowing and analyzing the legal consequences arising from authentic deeds that are based on false information. This research was conducted in Makassar, South Sulawesi Province, specifically at the Makassar District Court. This research was carried out by taking data from copies of decisions regarding the criminal act of ordering to place false information in authentic deeds. Apart from that, the author also conducted literature studies by reviewing books, literature and statutory regulations related to the problems. The result obtained is that the application of material law, in this case, is not appropriate because the element of the article being accused, namely Article 266 paragraph (1), which, in the author's opinion, is not appropriate the element of the use of the deed can cause harm, whereas the use of an authentic deed does not provide the damages alleged are selected by the Panel of Judges. Furthermore, the decision-making process carried out by the Panel of Judges, in the author's opinion, is not following the applicable legal rules because one of the elements in the article being charged is not following the facts in the trial. So, according to the author, imposing a crime on the defendant is inappropriate both in the Court of First Instance and the High Court.

Material and process invariant scaling laws to predict porosity of dense and lattice structures in laser powder bed fusion

Scaling laws represent an efficient way to describe complex physical phenomena efficiently and reliably by simplified relative quantities, which are holistic in the sense that they are invariant to changes in scale and therefore often universal. During part manufacturing in laser powder bed fusion additive manufacturing several such complex physical phenomena arise leading to unstable melt pool behavior and part porosity. Correlating processing parameters with melt pool quantities and eventually part properties such as porosity computationally efficiently can enable real-time build failure detection and process adaption leading to zero scrap rates in additive manufacturing. The efficient and reliable process-property correlation for dense materials is an ongoing field of research, whereas architected cellular and lattice structures, which are becoming more and more relevant in the context of additive manufacturing are rarely considered in this regard. In this contribution, a dimensionless number and the corresponding scaling law are derived to describe the correlation between porosity and process parameters for components manufactured by laser powder bed fusion. The scaling law is tested and validated for the commonly used alloys Ti-6Al-4V and AlSi10Mg on both dense and lattice structures regarding its suitability to predict the type and amount of porosity in additively manufactured components. The objective of this work is to foster reliable and predictable part quality and enable quality-driven build rate optimization.

Determination method for magnetic momentum compensation temperature of ferrimagnets by extrapolating from narrow temperature range

We propose here an experimental method to determine the magnetization compensation temperature of ferrimagnets. Our method utilizes the first-order derivative of the spontaneous net magnetization with respect to the temperature and then analyzes the results within the context of the Bloch's law of ferrimagnetic materials. This method enables us to extrapolate the compensation temperatures, even when they exceed the measurement limit. Consequently, a wide range of compensation temperatures can be determined using a single experimental setup. The present method provides a versatile tool for analyzing huge compensation temperature in the emerging field of ferrimagnetic and antiferromagnetic spintronics.

Large deflection response of functionally graded porous structures considering geometrical nonlinearity using an improved FSDT

This study’s objective is to propose a full 3D finite element modeling for examining the geometrically nonlinear (NL) response of functionally graded (FG) porous materials with plates, ring, and cylindrical shapes. An improved first-order shear deformation theory (IFSDT) is utilized in order to develop the 3D solid-shell element. The governing equations are developed in a way that offers a parabolic distribution of the transverse shear strains through the FG porous shell thickness and a zero condition of the transverse shear stresses on the top and bottom surfaces. The given IFSDT solid-shell element has the ability to model any kind of shell structures and incorporates a 3D material law. In this study, two types of porosity distribution functions are considered. The effectiveness of the present IFSDT solid-shell element is demonstrated through linear (L) and NL numerical examples. The effect of the porosity distribution, porosity coefficient, power-law index, geometrical design parameters, and boundary conditions on the geometrically NL response of FG porous shells structures is evaluated.

Study on coupled heat-water-vapor transfer in buffer material based on SPH method

To study the hydrothermal evolution law in buffer materials, based on the heat balance equation of unsaturated soil and the quality control equation of water migration, a coupled heat-water-vapor model of unsaturated soil is proposed. This model comprehensively considers the transition process of water vapor, the heat transfer caused by water flow and vapor migration, as well as the influence of temperature potential on water flow and vapor migration. The smoothed particle hydrodynamics (SPH) method can be used to calculate their evolution process conveniently. In the solution, the vapor content of heat balance equation is solved first, and then the water content and temperature field are solved, so as the coupling of temperature field between water and vapor field is implemented. The rationality of the model is verified by the tested results of soil column test. According to the established theoretical model, the heat-water-vapor three-field coupling problem of the buffer material in the repository was simulated and studied, and the hydrothermal evolution law inside the buffer material was revealed. On this basis, the influence of the change of groundwater pressure and heat source temperature on the hydrothermal evolution law of buffer material was further analyzed.

Law Enforcement Efforts by the Police in Eradicate Action Criminal Gambling on Line

The new crimes brought about by the development of technology are wrong one of them is online gambling. With the development of information technology This online gambling does not require a place or arena to gamble different with gambling in a way conventional Which need something place For get together and gamble. In online gambling, players only need to visiting gambling places on online gambling sites that can be found online easy in Internet and anyone can access it easily. The specifications of this research are analytical descriptive. Data source used is data primary And data secondary. Data primary is data Which obtained directly from the field or from the first source and has not been processed by party other. Whereas data secondary obtained from study literature Which consisting of materials law primary, material law secondary And material law tertiary.The results of the research and discussion can be concluded Indonesia itself already has a legal basis regarding online gambling, namely as stated in Article 27 paragraph 2 of the ITE Law Number 19 of 2016. Meanwhile, threats against This violation is regulated in Article 45 paragraph 2. When conducting a police investigation have authority do arrest, detention, foreclosure And search. Before 2011, the person dealing with online gambling crimes was Subdit III Unit I Tipidum Bareskrim Police Headquarters. Since 2011 in charge online gambling crime is the Cyber Crime IT Unit Sub-Directorate in collaboration with Subdit III Unit I Tipidum which specifically handles online gambling crimes. By reality, implementation enforcement law by cyber National Police to practice Online gambling has complex obstacles because it looks at the game circle gambling on line This very narrow For prosecuted in a way physique to perpetrator Because implications these are factors technological sophistication

Uniaxial ratcheting and ductile damage in structural steel with a stochastic spreading of experimental data

AbstractThis paper provides new experimental data regarding inelastic strain accumulation in structural steel samples. The samples are subjected to stress‐controlled cyclic loading with positive mean stress within each cycle; the loading blocks are combined in a complex pattern to study the effect of load history. A large‐strain ratcheting model is constructed based on a material law with a nonlinear kinematic and isotropic hardening. A new rule of ductile damage accumulation is suggested and a class of models with hardening stagnation is introduced. We show that models which include the hardening stagnation describe the experimental data more accurately. Unfortunately, due to a large spread of mechanical properties from sample to sample, it is impossible to describe the entire set of experiments using a single set of parameters. To address this challenge, we have developed novel mathematical tools for parameter identification in the context of stochastic variations in mechanical properties. These tools include the concept of a collar of model responses and the notion of protrusion. We propose an extended parameter identification problem that rethinks the standard error functional. We demonstrate that the extended identification problem effectively accounts for the large spread observed in experimental data when applied to the developed ratcheting model.

Damage constitutive model of rock and application based on strength theory

Abstract Extending the one-dimensional damage constitutive model of rock materials to 3 dimensions using classical methods fails to capture the significant differences in tensile, compressive, and shear strengths exhibited by the rock materials. Consequently, it is necessary to revise the existing damage constitutive model to describe the damage evolution law and constitutive relationship of rock materials more accurately and provide a theoretical basis for the safety and stability analysis of underground engineering more scientifically, thus ensuring the sustainable development of underground engineering. By introducing the Weibull distribution function and building upon strength theory, a correction function was established. This correction function adjusted the equivalent strain, enabling the development of a 3-dimensional damage constitutive model that accounted for the varying tensile, compressive, and shear strengths of rock materials. The impact of various parameters on the model's fitting effectiveness was evaluated, and a comparative analysis was conducted against pertinent experimental results. Using the theory of neutral axis deviation, the relationship between bending moment and damage variables in a purely bending rock beam was derived. The study revealed that all parameters of the damage constitutive model could be derived from the uniaxial stress-strain curve, and its theoretical findings exhibited strong agreement with experimental results obtained from rock and rock-like materials under uniaxial tension, compression and triaxial compression. Based on the examined cases, it was concluded that, when considering both tensile and compressive damage, the ultimate bending moment of a rock beam was approximately one-third of its elastic limit bending moment in an undamaged state. The results have verified the feasibility of the damage constitutive model.

Statistically compatible hyper-reduction for computational homogenization

The computational bottleneck of reduced order models (ROMs) in nonlinear homogenization is usually given by the local material laws, which need to be evaluated in a large number of microscopic integration points. Hyper-reduction methods use only a small subset of the integration points and reach tremendous speed-ups at high accuracy. However, the underintegration breaks the overall compatibility of the microscopic strain field and is in this sense disrespecting the microscopic boundary value problem. Here, a new type of generalized integration points is introduced in strain space in order to remedy this shortcoming. Being inspired by results from nonlinear homogenization theory, the concept of statistical compatibility is developed and forms the theoretical basis for the new integration points, which respect the compatibility of the microscopic strain field in a statistical sense. The statistically compatible integration points can be derived offline and replace the conventional ones in a Galerkin-projection based setting with global modes identified via proper orthogonal decomposition (POD). The method is tested for various reinforced composites, indicating that 10-20 integration points are often sufficient to reach errors smaller than 3%, with CPU-times in the μs-range (per time step). A possible extension of the method for problems with higher nonlinearity and stronger field fluctuations is discussed within the context of a porous microstructure.

Improved-FSDT-based solid-shell element for buckling analysis of plate, spherical cap, and cylindrical shell of FG porous materials

This study's objective is to propose a full three-dimensional finite element modeling for examining the buckling behaviors of functionally graded (FG) porous materials with plates, spherical cap, and cylindrical shapes. An improved first-order shear deformation theory (IFSDT) is utilized in order to develop the three-dimensional solid-shell element. The governing equations are developed in a way that offers a parabolic distribution of the transverse shear strains through the FG porous shell thickness and a zero condition of the transverse shear stresses on the top and bottom surfaces. The given IFSDT solid-shell element has the ability to model any kind of shell structures and incorporates a three-dimensional material law. In this study, two types of porosity distribution functions are considered. The performance of the current IFSDT solid-shell element has been demonstrated by examining the buckling behavior of Functionally Graded Porous plates, spherical caps, and cylindrical shells. The effect of the porosity distribution, porosity coefficient, power-law index, geometrical design parameters and boundary conditions on the buckling behaviors of FG porous shells structures is evaluated.

Optimized Heat Distributions for Laser‐Assisted Forming

Forming is limited for many modern materials due to their brittleness. Recent publications propose therefore partial heating of the forming areas, e.g., with laser technology, however, without asking how to minimize the applied energy. This work discusses such an optimization of the temperature distribution to save energy, to avoid unnecessary changes of the material properties, and to minimize thermally induced deformations. The findings are demonstrated on a statically determined quasi 1D‐problem, namely, 3‐point‐bending, and showed for a certain material law (modelling a dual phase steel of type DP1000) that the concentration of heat on the central line of the forming area is counter‐productive and that the necessary energy can be significantly reduced with a well‐defined heating strategy. Furthermore, we discuss how to extend the analysis to more complex problems which can be treated only numerically.

Experimental study of confined diffusion of rough and smooth ellipsoidal colloids

The study of diffusion in complex confined environments has received great attention in the field of condensed matter physics. The emergence of colloidal systems provides an excellent experimental model system for quantitatively studying the confined diffusion of microscopic particles. When colloidal particles change from spherical to ellipsoidal shape, the system presents anisotropic diffusion dynamics. Recent studies have found that rough surfaces, another important physical parameter of colloids, can lead to unusual rotational dynamics in spherical colloidal systems. However, due to the lack of a suitable experimental system, little is known about the effect of rough surfaces on the confined diffusion of ellipsoidal colloidal particles. In this work, rough colloidal spheres, rough colloidal ellipsoids, and smooth colloidal ellipsoids are prepared, and then monolayer colloidal samples are prepared to study the confined diffusions of these two types of ellipsoids in dense packing of the rough sphere colloids. By calculating the mean square displacement, intermediate self-scattering function, and orientation correlation function of the ellipsoids, we quantitatively characterize the diffusion dynamics of rough and smooth ellipsoids in varying concentrations of rough spheres. The results indicate that the translational diffusion and rotational diffusion of rough ellipsoids and smooth ellipsoids slow down as the concentration of rough spheres increases. This is due to the confinement of the ellipsoid by the surrounding spheres. At low stacking fractions of spheres, smooth and rough ellipsoids show similar translational diffusion and rotational diffusion. However, as the stacking fraction of spheres increases, there is a significant difference in advection diffusion between rough ellipsoids and smooth ellipsoids. The advection diffusion of rough ellipsoids is significantly slower than that of smooth ellipsoids. This is because the rough surface strongly inhibits rotation, meaning that the rotational diffusion of the rough ellipsoids is significantly slower than that of the smooth ellipsoids. By extracting the diffusion coefficients for translation and rotation from the ellipsoid's long-time mean-square displacements, we find that at <i>ϕ</i> = 0.60 and 0.65, the diffusion coefficients of rough ellipsoids are smaller than those of smooth ellipsoids. The translational diffusion coefficient of the rough ellipsoids is notably smaller than that of the smooth ellipsoids. However, the rotation diffusion coefficient of the rough ellipsoids is not significantly different from that of the smooth ellipsoids. This suggests that the rough surface mainly affect translational diffusion, strongly suppressing the translational diffusion of the ellipsoids. By calculating the displacement probability distribution for ellipsoidal motion, we find that at <i>ϕ</i> = 0.65, the translational displacements of rough ellipsoids have a relatively narrow distribution. This suggests that the translational motion of particles is suppressed by the rough surface. However, the distributions of rotation displacement for smooth ellipsoids and rough ellipsoids are very similar, indicating that the rough surface has less influence on particle rotation. At <i>ϕ</i> = 0.74, the rough surface suppresses both the translation and the rotation of the ellipsoid, resulting in a narrower displacement distribution than in the case of smooth ellipsoid. These findings suggest that rough surfaces significantly impede ellipsoidal diffusion, leading the translational and rotational motions not to occur simultaneously. This study provides an in-depth understanding of the role of rough surfaces of colloidal particles in confined diffusion, as well as an experimental basis for explaining the diffusion laws of rough materials.

Solitary deformation waves in two coaxial shells made of material with combined nonlinearity and forming the walls of annular and circular cross-section channels filled with viscous fluid

The aim of the paper is to obtain a system of nonlinear evolution equations for two coaxial cylindrical shells containing viscous fluid between them and in the inner shell, as well as numerical modeling of the propagation processes for nonlinear solitary longitudinal strain waves in these shells. The case when the stress-strain coupling law for the shell material has a hardening combined nonlinearity in the form of a function with fractional exponent and a quadratic function is considered. Methods. To formulate the problem of shell hydroelasticity, the Lagrangian–Eulerian approach for recording the equations of dynamics and boundary conditions is used. The multiscale perturbation method is applied to analyze the formulated problem. As a result of asymptotic analysis, a system of two evolution equations, which are generalized Schamel– Korteweg– de Vries equations, is obtained, and it is shown that, in general, the system requires numerical investigation. The new difference scheme obtained using the Grobner basis technique is proposed to discretize the system of evolution equations. Results. The exact solution of the system of evolution equations for the special case of no fluid in the inner shell is found. Numerical modeling has shown that in the absence of fluid in the inner shell, the solitary deformation waves have supersonic velocity. In addition, for the above case, it was found that the strain waves in the shells retain their velocity and amplitude after interaction, i.e., they are solitons. On the other hand, calculations have shown that in the presence of a viscous fluid in the inner shell, attenuation of strain solitons is observed, and their propagation velocity becomes subsonic.