Material Law Research Articles

Time-dependent electromagnetic scattering from dispersive materials

Abstract This paper studies time-dependent electromagnetic scattering from obstacles that are described by dispersive material laws. We consider the numerical treatment of a scattering problem in which a dispersive material law, for a causal and passive homogeneous material, determines the wave–material interaction in the scatterer. The resulting problem is nonlocal in time inside the scatterer and is posed on an unbounded domain. Well-posedness of the scattering problem is shown using a formulation that is fully given on the surface of the scatterer via a time-dependent boundary integral equation. Discretizing this equation by convolution quadrature in time and boundary elements in space yields a provably stable and convergent method that is fully parallel in time and space. Under regularity assumptions on the exact solution we derive error bounds with explicit convergence rates in time and space. Numerical experiments illustrate the theoretical results and show the effectiveness of the method.

Tensorial harmonic bases of arbitrary order with applications in elasticity, elastoviscoplasticity and texture-based modeling

In continuum mechanics, one regularly encounters higher-order tensors that require tensorial bases for theoretical or numerical calculations. By using results from [Formula: see text] representation theory, we present a method to derive tensorial harmonic bases which unifies existing approaches in one framework. Applying this convention to symmetric second-order tensors results in a second-order harmonic basis which, for example, simplifies the depiction and numerical handling of stiffness tensors for most common material symmetries and reduces the computational effort involved in implementations of incompressible elastoviscoplastic material laws. The same convention can be applied to texture analysis to yield tensorial texture coefficients for both polycrystals and fiber-reinforced composites. Rotations of higher-order tensors are particularly efficient in harmonic bases as both material and index symmetries can be exploited. While special attention is given here to the examples of small-strain material laws and texture analysis, the framework is entirely general and can be used to simplify calculations in other physical contexts involving tensors of arbitrary order and symmetry. A Python implementation of the harmonic basis convention defined in this work is available as a Supplementary Material.

Changes in Pretrial Authority through the Decision of the Constitutional Court

Pretrial authority underwent changes in authority through the Constitutional Court Decision. This research aims to examine and analyze several judicial reviews of pretrial objects, consisting of Constitutional Court Decision Number 21/PUU-XII/2014, Constitutional Court Decision Number 109/PUU-XIII/2015, Constitutional Court Decision Number 102/PUU-XIII/ 2015 & Constitutional Court Decision Number 130/PUU-XIII/2015, which as a whole, the a quo decision changes pre-trial authority. The formulation of the problem in this research is 1). What is the role of the Constitutional Court in making legal breakthroughs regarding pretrial? 2). What are the dynamics and issues behind the Constitutional Court's decision in changing pre-trial authority? The research method used in this research uses doctrinal legal research methodology. This research concludes that: 1). The role of the Constitutional Court in making legal breakthroughs regarding pre-trial can be seen in, first: the Constitutional Court determines that the determination of suspects is included in the object of pre-trial. Second: The Constitutional Court limits the scope of pre-trial material law to the position of KPK investigators which cannot be equated with POLRI investigators, that KPK investigators stand alone with Law no. 30 of 2003 as amended in Law no. 19 of 2019 concerning the Corruption Eradication Commission. Third: ending the multiple interpretations of judges, discontinuing pre-trial applications when the case has been examined or entered the main case. Fourth: the submission of a notification letter for the start of an investigation is extended not only to the public prosecutor, but also to the suspect and the reporter/victim. 2). The dynamics and issues behind the Constitutional Court's decision in changing pre-trial authority, namely related to pre-trial authority in determining suspects, the dismissal of pre-trial petitions, the submission of SPDP, the entire Constitutional Court's decision has not been followed up in the form of a revision of the law

Claim in a civil proceeding Ancient Rome

The author points out that the lawsuit, as a legal institution, has an extremely long history. Like most civil institutions, its origins are connected with the law of Ancient Rome. The article is devoted to the analysis of the institution of the claim in the law of Ancient Rome. It is argued that subjective material rights were perceived by Roman legislators, court officials and lawyers not from the point of view of their material content, but the ways of protecting these rights. Claims were not derived from subjective material rights, but, on the contrary, they could confirm their existence. Subjective material rights and their judicial implementation were considered as one whole, preventing the Romans from dividing the law into material and procedural law. It is indicated that the lawsuit did not act as a universal procedural tool that protected against all possible civil offenses. Roman law developed as a system of actions that provided protection in a situation where the few laws in the field of civil law were outdated and could not effectively provide protection to the individual. The peculiarity of the claim within three forms of civil process of Ancient Rome is revealed: legislative, formulary and extraordinary. In the period of the legislative civil process, the claim had to be presented to the court in such a way that it repeated the verbal norm of the law, which the person referred to in his case, otherwise he lost it. Quite often, the verbal voicing of one’s claims had to be accompanied by certain gestures literally to the norm of the law. At the time of the formal civil process, the plaintiff presented the claim to the court also orally, but without observing the claim formalism, which made it difficult to access the court. At that time, the praetors began to record the claim in writing in a special act-instructions, where the judge was given instructions on how to resolve the case. With the help of these acts, praetors could protect social relations not regulated by custom or law. The extraordinary civil process brought the institution of the lawsuit closer to its modern understanding: an oral, and then a written claim by the plaintiff to the defendant, which must be decided by the court. The lawsuit was considered as a posed question, to which the court decision should give an answer.

Downwind and upwind approximations for primal and dual problems of elasto-plasticity with Prandtl–Reuss type material laws

Modern adaptive finite element (FE) algorithms for solution of initial-boundary-value-problems (IBVP) employ goal-oriented error measures in order to assess the quality of computational results for the physical event under investigation. However, traditional time-stepping algorithms for solution of the corresponding dual problem run backwards-in-time, which due to additional storage requirements might become a serious drawback when an extensive number of time steps for the FEM simulation arises. In this paper, we take advantage of an end-boundary-value-problem (EBVP) associated to IBVP, with corresponding dual-problem running forwards in time. In order to obtain a unified framework for numerical approximation of primal and dual weak forms for both, IBVP and EBVP, respectively, we apply the concept of downwind and upwind approximations not only to the trial functions but also to the test functions. This results into eight different integration schemes. On this basis, as a main result of this contribution, a time-stepping algorithm is obtained, which runs forwards-in-time for the dual problem and therefore avoids the additional storage requirements of the traditional backwards-in-time stepping procedures. The presented algorithm is numerically tested and validated for a CT-specimen for elastic and elasto-plastic behavior, where the constitutive equations are written in Prandtl–Reuss type format.

Asbestos: Communicating the Health Issues Derived from Fibrous Minerals to Society

Asbestos, also known by its commercial name “amianthus”, has been widely used in various industries due to its unique properties. However, the extensive use of asbestos has had serious consequences for human health, most notably asbestosis, an irreversible chronic lung disease. Asbestosis increases the risk of lung cancer and malignant mesothelioma, both of which are fatal. Applied sciences such as microscopy (optical and scanning electron microscopy) and geochemistry have been fundamental in characterizing the mineral fibers of asbestos to understand its role in human health. We previously used these techniques to characterize these fibers; in this study, we explored the issues associated with asbestos and asbestosis, as well as the challenges facing science communication strategies in effectively informing society and workers about these risks. The lack of scientific culture, in general, has led to a lack of public awareness of the risks of asbestos. As such, effective communication and outreach plans and strategies, including the visualization of the fibers to demonstrate why problems arise if inhaled, must be implemented to address these challenges. Educational campaigns, guidelines, and plans that are informative and actionable, teaching workers, communities, and the public about the risks of asbestos are crucial. A general knowledge of mineralogy and geochemistry is needed, and providing and disseminating proper scientific communication may help to close the knowledge gap. We use examples and experience from Spain and Italy to illustrate this matter, as we have been working on the characterization of ultramafic complexes in these countries for more than ten years. Additionally, because these countries have strict laws for asbestos-containing materials, they are currently involved in retiring and demolishing buildings and infrastructure that contain asbestos.

Experimental and numerical analysis of the vibrational behaviour of metallic structures filled with damping materials

This work focuses on characterizing and modeling the vibrational behavior of hollow metallic structures filled with damping material. Vibration tests are first carried on a hollow structure, then two filling materials are considered: a cast viscoelastic material and a granular material composed of epoxy and polyurethane beads. Modal parameters (natural frequencies, modal damping and mode shapes) are extracted from the Frequency Response Functions with experimental modal analysis tools. Damping ratios greater than 5~\% are measured. Given the difference in the nature of the filling materials, dissipation mechanisms are different. The effectiveness of a damping material depends on the type of structural modes (bending, torsion or wall mode) to be damped, and dissipation in filling materials cannot be modelled by a constant loss factor or viscous damping. Consequently, a finite element modeling of the structure filled with viscoelastic material is proposed. Numerical modal parameters of the structure are correlated with experimental measurements. By extension, a bead mix material law, based on a fractional Zener model, is proposed, whose parameters are obtained by inverse identification.

Study on Contact Characteristics of Chain Track Interface and Distribution Law of Coal Bulk Material of Short-distance Scraper Conveyor

Study on Contact Characteristics of Chain Track Interface and Distribution Law of Coal Bulk Material of Short-distance Scraper Conveyor

Three-phase lag model for thermal conductivity of a thermo-viscoelastic porous medium

This paper investigates the propagation of waves and the thermal behavior in a thermo-viscoelastic porous medium using the three-phase-lag (TPL) model which accounts for phase lags in the heat flux vector, temperature gradient and thermal displacement gradient. The study aims to capture the interactions between thermal, mechanical, and structural properties of the thermo-viscoelastic porous, isotropic, homogeneous medium. The governing equations, incorporating the TPL heat conduction law and constitutive relations for the viscoelastic porous material, are derived and analyzed. The impact of relaxation times, porosity, and viscoelastic parameters on heat propagation is investigated through analytical solutions by normal modal analysis. Analytical representations of various physical quantities (stresses components, displacements, temperature,…) in the material's domain are derived. These expressions are then assessed numerically for a specific material, with the outcomes depicted graphically. A comparison is made between the predictions of the three-phase-lag (TPL), the dual-phase-lag (DPL) and Lord–Shulman (L–S) theories in the absence and presence of voids.

Experimental and digital twinning in ZnAlMg coatings

Twinning is a major deformation mechanism in various materials, especially when few dislocation slip systems are operative. It is the case of zinc-rich coatings in galvanised steel sheets, made of pancake grains on a substrate and where the slip systems with a non-vanishing component along the c-axis present high critical resolved shear stress values. In addition, the abrupt lattice orientation change associated to twinning, the stress relaxation during its propagation and the localised nature of its early stages make it difficult to reproduce this deformation mechanism by using classical crystal plasticity models conceived for dislocation slip. In this sense, this work proposes a hierarchy of three twinning models in combination with a dislocation slip crystal plasticity model, for the case of a ZnAlMg coating. These three models are: a relaxed-Taylor model applied to individual crystal orientations of the coating, a “pseudo-slip” model for twinning and a localised twinning model. The latter incorporates a linear softening in the material law accounting for the unstable twinning initiation and enforces twinning lattice reorientation. A microstructure portion extracted from an in-situ SEM tensile experiment on galvanised steel is used to perform 3D full-field finite element simulations within a finite strain formulation. SEM observations and EBSD acquisitions are used to compare simulation and experimental results during the different steps of the in-situ SEM test, regarding the deformation and damage modes of the zinc-rich coating. The focus is set on twinning evolution inside some individual grains, and the pros and the cons of the three models are finally discussed.

Sound Insulation Characteristics of Sandwich Thin-Plate Acoustic Metamaterial: Analysis and Optimization

Addressing the demand for low-frequency noise control in ships and aiming to overcome the limitations imposed by the mass law of traditional materials, a sandwich thin-plate acoustic metamaterial (SPAM) was developed in this study. This structure is characterized by its simplicity and superior sound insulation performance. A sound insulation test was conducted to validate the exceptional low-frequency acoustic suppression capability of SPAM, and the effectiveness of the analytical model was also demonstrated. Subsequently, based on this model, a sensitivity analysis of the sound insulation characteristics of the SPAM relative to structural parameters was carried out. For the optimization process, the Logistic-Sine fusion chaotic mapping was employed to refine the dung beetle optimizer (DBO), enhancing the initial population distribution. The improved dung beetle optimizer (IDBO) was then used to further optimize and elevate the sound insulation performance of the SPAM. The outcomes indicate that the IDBO boasts superior optimization proficiency and accelerated convergence, while the optimized SPAM exhibits more remarkable sound insulation capabilities. Within the frequency range of 100–315[Formula: see text]Hz, the average sound transmission loss (STL) has increased by 11.94[Formula: see text]dB when compared to the pre-optimization values.

Mechanics of Materials: Multiscale Design of Advanced Materials and Structures

Materials can now be designed and architectured like structural components for targeted mechanical and physical properties. Structures and microstructures should not be studied independently and their design will benefit from a multiscale approach combining nonlinear continuum mechanics approaches and physical descriptions of elasticity, viscoplasticity, phase transformations and damage of microstructures, at various scales. The aim of the workshop was to gather outstanding junior and senior researchers in the various branches of mathematics, physics and engineering sciences suited to address the question of design of materials and structures by means of multiscale discrete and continuum approaches to their constitutive behavior. Examples include atomic or macroscopic lattices, random or periodic cellular materials, smart materials like shape memory alloys, 3D woven composites, acoustic and electromagnetic metamaterials, etc. Modern continuum mechanics relies on sophisticated constitutive laws for anisotropic materials exhibiting elastoviscoplastic behavior, still a field of intense research with new mathematical concepts. In particular size-dependent properties are addressed by resorting to generalized continua such as gradient or micromorphic and phase field models. The latter are attractive for the simulation of microstructure evolution coupled with mechanics, due to thermodynamic and metallurgical processes and damage. Scale transition and homogenization methods for continuous and discrete systems are required for the determination of effective material and structural behavior. Metamaterials are architectured materials specifically designed to achieve certain propagation and dispersion properties of elastic and plastic waves. Optimization strategies for the design of optimal architectures are involved in the design process. Target functions for optimization are now based on multicriteria (stiffness, strength, thermal expansion, transport properties, anisotropy etc.).

Computing laminate composite voxel properties using Mirtich formulas

AbstractComputational homogenization methods offer deeper insights into the mechanical behavior of heterogeneous materials, often exhibiting complex anisotropic properties due to intricate manufacturing processes. Micromechanical techniques exploit the knowledge of the material's microstructure to predict effective behavior. Digital material data, represented as voxels, require processing numerous image points. Despite the computational power of modern fast Fourier transform‐based numerical solvers, performance improvements are still valuable. The composite voxel technique, in its original form, furnishes voxels containing more than one material with a surrogate material law, resulting in higher accuracy. This work contributes to the understanding and application of composite voxels in computational micromechanics by integrating them into a level‐set‐based framework, providing a detailed methodology for deriving laminate composite properties using the formulas of Mirtich, and demonstrating their potential to enhance computational performance through a numerical example.

Flexure Performance of Textile-Reinforced Cementitious Composites with Novel Inclined Reinforcements.

Textile-reinforced cementitious composites have great potential to offer novel design opportunities for thin-section structures thanks to their superior material capabilities. In this work, new cementitious composites with novel reinforcement configurations are developed, which have superior mechanical properties. The cementitious composites contain inclined through-the-thickness reinforcements, and their enhanced performance on thin-section material hardening under flexural loading is demonstrated. Furthermore, a new practical FE modeling approach is proposed that involves the combined use of multiple cohesive regions and 1D reinforcement elements that pass through these regions with a bilinear material law. This approach provides a new computationally efficient modelling framework whereby reinforcement pull-out during hardening is readily captured without resorting to computationally demanding interface laws between the reinforcement and the cementititous matrix. The model can model enhanced hardening of new configurations and provides comparable results with the experimental findings. The model can be used in the modelling and design of novel cementitious composites with engineered reinforcement configurations. Overall, this study aims to open up new avenues for the smart material design of cementitious composites with novel structural reinforcements.

Unravelling the mechanics of gastric tissue: A comparison of constitutive models, damage probability and microstructural insights

With the increasing prevalence of obesity worldwide, bariatric surgery is becoming increasingly common. However, the mechanic of the gastric wall related to bariatric surgery complications remains to be investigated. This study aims to understand mechanical behaviour of stomach by developing advanced material laws for gastric tissue incorporating microstructure. A multi-scale characterisation of the porcine stomach wall was performed in the fundus and corpus anatomical regions and in circumferential and longitudinal orientations The protocol included uniaxial tensile testing until damage, survival analysis to provide damage probability, comparison of phenomenological (Fung and Ogden order 1, 2 and 3) and structural (Holzapfel fibre-reinforced) computational models fitted to the experimental data, and quantitative analysis of elastin and collagen fibre structure from histological slides. All constitutive models fitted the experimental data well (r2 > 0.988 and RSME<3.8 kPa). Longitudinal and circumferential elastic modulus in quasi linear phase were respectively 1.75 ± 1.2 MPa, 0.76 ± 0.35 MPa for fundus, and 2.30 ± 0.66 MPa, 1.36 ± 0.89 MPa for corpus, highlighting significant differences between orientations in fundus and corpus, with an overall softer fundus in the circumferential direction. Microstructure analysis illustrated collagen and elastin fibre orientation, dispersion and density. As microstructure appears to play an important role in stomach biomechanics, model incorporating fibre structure such as Holzapfel fibre-reinforced model, seem best suited to describe the material behaviour of the stomach wall. Future research should complement these findings with an expanded sample set in human models.

Prediction of sectional collapse of thin-walled structure under pure bending by nonlinear composite beam theory

Brazier (1927) found that when one dimension of the beam cross-section was relatively smaller than the others, large in-plane displacements over the cross-section might occur, even though the strains could remain very small. Under this circumstance, the so-called Brazier effect refers to the cross-sectional ovalization, which leads to nonlinear bending buckling and collapses. This paper studies the Brazier effect by the nonlinear Variational Asymptotic Beam Sectional Analysis (VABS) theory which considers finite cross-sectional deformations. Nonlinear VABS reduces three-dimensional (3D) continuum to a one-dimensional (1D) beam analysis and a two-dimensional (2D) cross-sectional analysis featuring both geometric and material nonlinearities without unnecessary kinematic assumptions. The present theory is implemented using the finite element method (FEM) in the VABS code, a general-purpose beam cross-sectional analysis tool. An iterative method is applied to solve the finite warping field for the classical-type model using the Euler–Bernoulli beam theory. The deformation gradient tensor is directly used to deal with finite deformation, various strain definitions, and several types of material laws. Numerical examples demonstrate the capabilities of VABS to predict the sectional collapse of thin-walled structures under pure bending.

Law Enforcement of Narcotics Crimes Against Children in The Drug Investigation Directorate of The Bali Regional Police Force

Children are a new generation of young people growing up in a nation, the child is a legal subject who has not reached the age of 18 (eighteen). Article 1 paragraph (15) of Law Number 35 of 2009 concerning Narcotics states that narcotics abuse is a person who uses narcotics without the right or against the law. If the perpetrator of the narcotics crime is a child, then in material law of course the child as the perpetrator of the narcotics crime can be charged following Article 112 of Law Number 35 of 2009, because the intended substance in the article is that it reads every person, which means that all people, both adults and children, can be subject to the article. narcotics abuse is qualified as a crime without a victim, which means that the victim of the crime is the perpetrator himself, so in the event of narcotics abuse, the victim (crime) is the child who abuses narcotics in addition to his qualifications as a perpetrator is a victim. So the investigators of the Bali Police Ditresnarkoba in enforcing the law on narcotics crimes against child perpetrators, attempted to do so through a diversion approach

Predicting the impact depolarization behavior of PZT-5H based on machine learning

In order to establish the relationship between the load and depolarized charge under stress waves, we established the stress depolarization experimental platform and obtained the time history curve of charge variation with the load. Then, we built a theoretical model of PZT-5H impact depolarization and physically described the model based on the characteristics of the experimental data and domain switching. Meanwhile, we obtained the uncertain parameters in the model by using the CBP neural network and the genetic algorithm. Finally, the effectiveness of the impact depolarization theory model was verified by comparing it with experimental values. The results indicated that the established PZT impact depolarization model can reflect the depolarization law of materials in the range of 0 ∼ 250 MPa stress waves. It provided a predictive method for the application of piezoelectric materials in extreme engineering such as contact fuses, pulse power supplies, and impact sensors.

Phase-field modeling of crack growth under coupled creep-fatigue

Crack growth under coupled creep-fatigue strongly influences service life of metallic components operating at high temperatures. However, there lack numerical models that enable direct simulations of crack growth and plasticity development under coupled creep-fatigue. In this study, a unified phase-field model is developed for simulating crack growth under fatigue, creep, and coupled creep-fatigue. This model is able to reproduce the Paris laws for both brittle and ductile materials in pure fatigue mode, which shows that the degradation rate due to cyclic stress in ductile materials is generally larger than that in brittle materials. Fatigue simulations with different yield strengths demonstrate that plasticity facilitates crack growth in typical ductile materials. High-throughput simulations are performed under coupled creep-fatigue conditions, with varying hold-stress levels and hold-time. By analyzing crack growth rate under different hold-time, a creep-fatigue interaction term is obtained. Simulation results demonstrate that the creep-fatigue interaction is caused by smaller stress gradient and enhanced degradation rate ahead of the crack tips under coupled creep-fatigue, compared to the situation of pure fatigue. This work reveals the origin of different Paris-law exponents in brittle and ductile materials and demonstrates how the interplay between creep and fatigue affects crack growth.

Effect of adhesive ductility on the bond behavior of CFRP-steel cohesive interfaces made with toughened epoxy resin

The strengthening of steel structures can be effectively performed using carbon fiber-reinforced polymers (CFRP) plates. Specifically, the behavior of corroded and fatigue damaged steel bridges can be significantly improved using externally bonded (EB) or unbonded composite reinforcements. For bonded composites, the bond between the reinforcement and the steel substrate is the weak link of the system. Indeed, cohesive failure within the adhesive layer represents the main failure mode, which makes the selection of a proper adhesive fundamental to achieve an improvement of the system load carrying capacity and fatigue resistance. Within this context, the use of toughened adhesives represents a promising solution. However, research regarding these adhesives is still limited. In this paper, 18 single-lap direct shear tests are performed to evaluate the cohesive behavior of toughened and traditional adhesives. For some specimens, the full-range bond behavior, including the load response snap-back, was experimentally captured. The digital image correlation (DIC) technique is adopted to evaluate the adhesives cohesive material law (CML). The effect of adhesive ductility, plate stiffness, and bonded length on the joint load response is investigated. Finally, experimental results are validated and discussed against the analytical predictions of a cohesive model based on a trapezoidal CML.