Fracture Mechanics

Fatigue crack propagation (FCP) of injection-moulded polystyrene (PS) and 95/5, 85/15 and 70/30 PS/high-density polyethylene (HDPE) blends at loading frequencies of 2 and 20 Hz was studied. The FCP results showed that increasing the HDPE content caused a progressive reduction of the fatigue crack growth rates, especially when a styrene/ethylenebutylene/styrene (SEBS) terpolymer was added as a compatibilizer. Increasing the loading frequency also led to a fatigue crack growth rate reduction. Moreover, the fatigue crack growth rates were lower at a given cyclic stress intensity factor range, K, when the crack propagated normal, instead of parallel, to the melt-flow direction during injection moulding. Fractographic observations indicated that discontinuous growth bands (DGBs), associated with the fracture of crazes in the plastic zone, were present through most or all of the fracture surfaces of the PS/HDPE specimens. In the presence of sufficient HDPE, these DGBs were formed by the initiation, growth and coalescence of large dimples initiated at HDPE particles ahead of the microscopic crack front, similar to a multiple crazing effect. The loading frequency effect on the FCP behaviour of these blends is attributed to a time-dependent deformation process. It is concluded that the FCP behaviour of these blends is strongly affected by the loading direction with respect to the matrix and minor phase orientation, by the presence of a compatibilizer, by the composition of the blend and by the testing conditions.

This study provides a comprehensive comparative evaluation of classical and modern predictive models for fatigue life in scraper rings of internal combustion engines, which operate under high thermo-mechanical stresses. Accurate fatigue life predictions are essential for optimizing engine component design, preventing both over- and under-engineering while ensuring long-term reliability. The effectiveness of both traditional models and newer advanced approaches was analyzed using loading profiles that replicate real-world engine operating conditions. Results indicate that stress life models offer more reliable predictions for high-cycle fatigue scenarios, while strain-life models perform better under low-cycle fatigue conditions. Furthermore, fracture mechanics models show great promise in predicting crack propagation and identifying failure mechanisms. Detailed inspections and Légraud-Poirier (LP) tests confirmed fatigue-induced cracking at critical locations of the scraper rings, emphasizing the importance of incorporating multi-axial loading in fatigue assessments. The findings underscore the necessity for using comprehensive loading profiles and thorough inspections to enhance the accuracy and dependability of fatigue life predictions, which are critical for improving the performance and durability of engine components.

In this paper, the authors consider a problem with comprehensive properties in terms of form and content in the space L 2 [(a, b) × (c, d)] × C[0, T], T < 1. In terms of time form, we assume that the time phase delay is implicitly contained in a nonlinear differential integral equation. The positional part is considered in two dimensions, and the position's kernel is a general singular kernel, many different forms of which will be derived. In terms of content, all of the previously established numerical techniques are only appropriate for studying special cases of the kernel separately but are not suitable for studying the general kernel. This led to the use of the Toeplitz matrix method, which deals with the kernel in its extended nonlinear form and the special kernels will be studied as applications of the method. Moreover, this method has the advantage of converting all single integrals into regular integrals that can be easily solved. Additionally, the researchers examine the solution's existence, uniqueness, and convergence in this paper. The error and its stability are also studied. At the end of the research, the authors studied some numerical applications of some of the singular kernels derived from the general kernel, examining the approximation error in each application separately.

In level-3 Leak-Before-Break (LBB) analysis, stability of a postulated through-wall circumferential crack is demonstrated by simplified fracture mechanics calculations. Detailed experimental studies, conducted by the authors, have revealed that the conventional assessment procedure used to demonstrate LBB is too conservative. There is a large factor of safety due to system indeterminacy. It was observed that the critical load of a cracked piping system (with even a large through-wall circumferential crack of about 120 ) is of the order of 75e90% of the collapse load of the uncracked piping system. Reduction in load carrying capacity is even less for a piping system having an off-centre crack. This article discusses the above-mentioned aspects in detail. Detailed 3-D elastic-plastic finite element analyses of some of these tests were performed. The suitability of these numerical results to predict crack initiation load in light of the experimental data is discussed.

Factor is one of the important parameters in fracture mechanics. One of the common geometries in evaluating of fracture mechanics problems is contact of tilted wedge with half plane that in this article Unsymmetrical tilted wedge geometry has been studied and digital Shearography as a non-destructive technique is applied to determine mixed mode stress intensity factors in a half plane with vertical edge crack which is subjected to an unsymmetrical tilted wedge. Optical setup with two in-plane illumination source is used to determine purposed strain variable and consequently obtain the mixed mode stress intensity factors as a result of applying linear elastic fracture mechanics (LEFM). The results of Shearography technique contains some fringes which contain the information needed to obtain the strain variables. To utilize the advantage of whole field Shearography and to minimize random experimental errors, the least square method is used to obtain SIF. In order to verify the obtained results accuracy, the experimental results were compared with the results of finite element method. The difference between two results is nearly 19%. The comparison of the experimental results and the numerical results proves the credibility and potential of this nondestructive method in measurement applications. Then the effect of crack size and gap of tilted wedge from crack tip on Stress Intensity Factors have been investigated. Finally it shown that in this problem Stress Intensity Factor in first mode of fracture is zero, so only second mode of fracture should be considered.

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In this paper we analyze the problem of a penny-shaped hydraulic fracture propagating parallel to the free-surface of an elastic half-space. The fracture is driven by an incompressible Newtonian fluid injected at a constant rate at the center of the fracture. The flow of viscous fluid in the fracture is governed by the lubrication equation, while the crack opening and the fluid pressure are related by singular integral equations. We construct two asymptotic solutions based on the assumption that either the solid has no toughness or that the fluid has no viscosity. These asymptotic solutions must be understood as corresponding to limiting cases when the energy expended in the creation of new fracture surfaces is either small or large compared to the energy dissipated in viscous flow. It is shown that the asymptotic solutions, when properly scaled, depend only on the dimensionless parameter R, the ratio of the fracture radius over the distance from the fracture to the free-surface. The scaled solutions can thus be tabulated once and for all and the dependence of the solution on time can be retrieved for specific parameters, through simple scaling and by solving an implicit equation.

This note deals with the problem of a penny-shaped hydraulic fracture propagating in an impermeable elastic solid. Growth of the fracture is driven by injection of an incompressible Newtonian fluid at the center of the fracture. The solution is restricted to the so-called viscosity-dominated regime where it can be assumed that the solid has zero toughness. The paper describes the construction of a semi-analytical similarity solution, which incorporates the known singularity of the fluid pressure at the center of the fracture and at the tip and which is based on series expansions of the fracture opening and fluid pressure in terms of Jacobi polynomials.  2001 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS hydraulic fracture / fracture mechanics Cette note traite du problème d'une fracture hydraulique circulaire se propageant dans un milieu élastique imperméable. La croissance de la fracture est causée par injection d'un fluide newtonien incompressible au centre de la fracture. Cette étude est restreinte à l'analyse du régime de propagation dominé par la viscosité, pour lequel on peut admettre que le solide n'a pas de tenacité. Cette note décrit la construction d'une solution autosemblable semi-analytique qui tient en compte le comportement singulier de la pression du

In the current paper, a numerical investigation based on the finite element method was constructed to analyse fracture mechanics of two L-shaped sheets welded with resistance welding. The fracture behaviour of the welded structure is considered with the assumption of a crack at the interface of the welded sheets. The study was treated as a linear elastic fracture mechanics problem in mixed mode, under plane stress conditions. Computations were performed using the commercial FE software package ABAQUS. The modelling results highlight the dependence of the stress intensity factors on key design parameters of spot welds such as nugget diameter, bent curvatures, sheet thickness, material properties and the applied load. Méthode des éléments-finis ; soudage par point ; mécanique de la rupture ; facteur d'intensité de contrainte ; mode mixte

The study presents the crack mouth opening and propagation of cracks in a composite material printed by material extrusion subjected to monotonic loading. The composite material is made out of a nylon matrix (with embedded short carbon fiber—called Onyx®) and reinforced with continuous Kevlar fibers. Three-point bending tests were performed on notched specimens built according to ASTM-E399. Tests were digitally recorded to extract crack opening displacement (COD) and crack length data through image treatment techniques (using ImageJ), and results were analyzed using linear elastic fracture mechanics parameters through the use of COD. Therefore, the crack mouth opening was established, and fracture toughness was found to be 46 MPa√m. Additionally, microscopy analysis identified fracture zones, crack initiation, transition, and final rupture. The observed failure mechanisms were matrix cracking, fiber pull-out, fiber breakage, and defects such as non-proper fiber-matrix bonding.

A numerical model was developed to simulate the progressive delamination of a composite subjected to mode I fatigue loading regimes of varying amplitude. The model employs a cohesive zone approach, which combines damage mechanics and fracture mechanics, and requires only standard material data as input, namely the delamination toughness and the fatigue delamination growth curve. The proposed model was validated against delamination growth data obtained from a fatigue test conducted on a DCB specimen. The model predictions agree very well with the experimental results. This model is an initial step toward life prediction of composite structures subjected to complex fatigue regimes.

We show that the Backus (1962) equivalent-medium average, which is an average over a spatial variable, and the Gazis et al. ( ) effective-medium average, which is an average over a symmetry group, do not commute, in general. They commute in special cases, which we exemplify.

A generally anisotropic elasticity tensor, which might be obtained from physical measurements, can be approximated by a tensor belonging to a particular material-symmetry class; we refer to such a tensor as the effective tensor. The effective tensor is the closest to the generally anisotropic tensor among the tensors of that symmetry class. The concept of closeness is formalized in the notion of norm. Herein, we compare the effective tensors belonging to the transversely isotropic class and obtained using two different norms: the Frobenius norm and the L 2 operator norm. We compare distributions of the effective elasticity parameters and symmetry-axis orientations for both the error-free case and the case of the generally anisotropic tensor subject to errors.

We show that the Backus (1962) equivalent-medium average, which is an average over a spatial variable, and the Gazis et al. (1963) effective-medium average, which is an average over a symmetry group, do not commute, in general. They commute in special cases, which we exemplify.

The paper analyses the thermomechanical coupling between a cantilever aluminium beam and an embedded SMA ribbon. The SMA is selected to be Nickel-Titanium (NiTi) because of the high strength and large strains associated with this material. The actuation of the beam is achieved by applying a current across the SMA ribbon in order to heat the beam above the transition temperature. We show that the actuated beam exhibit the essential functions of an active system, i. e. the deflected beam may return to the initial configuration.

Composite systems are a generally-accepted method for repairing corroded and mechanically-damaged onshore pipelines. The pipeline industry has arrived at this point after more than 15 years of research and investigation. Because the primary method of loading for onshore pipelines is in the circumferential direction due to internal pressure, most composite systems have been designed and developed to provide hoop strength reinforcement. On the other hand, offshore pipes (especially risers), unlike onshore pipelines, can experience significant tension and bending loads. As a result, there is a need to evaluate the current state of the art in terms of assessing the use of composite materials in repairing offshore pipelines and risers. The significance of the body of work presented herein is that this study is the first comprehensive evaluation of a composite repair system designed for the repair of offshore risers using a strain-based design method coupled with full-scale prototype test...

Evaluation of pine raw material for construction using visual classification. In this paper are presented the results of comparative research of structure wood sorted by visual methods and strength examinations. The pine wood from the vicinity of Sulechowo was used for the research. Physical properties of wood (density, moisture content and annular growth rings) and mechanical properties (module of elasticity) were tested. The samples, divided into quality classes, were subjected to visual evaluation. The results of the evaluation were compared with the results of tests carried out on universal testing machine.

We introduce the Recursive Expansive Hypergeometric Calculus (REHC), a novel and unified mathematical framework incorporating recursion, fractality, and non-locality. We formalize this approach through axioms derived from recursive Lie algebra theory, hypergeometric field theory, fractional recursive calculus, multifractal spacetime geometry, recursive gauge theory, and influence sheaf cohomology. Our theorems establish its consistency, stability, and broad applicability, suggesting extensions to Lie theory, differential geometry, quantum gravity, and field theory. Numerical validation demonstrates the computational feasibility and robustness of this framework, providing a foundation for further exploration.

The Recursive Expansive Hypergeometric Calculus (REHC) is a mathematical framework that merges recursive processes with hypergeometric and fractal structures, offering a self-consistent, respectable approach to modeling phenomena in various branches of physics. This framework incorporates recursive Lie algebra theory, hypergeometric field theory, fractional calculus, and multifractal spacetime geometry. The axioms governing REHC are derived from these domains and produce recursive, fractal-like structures that are stable and consistent under their own mathematical rules. Key results include recursive deformations of Lie algebras, the convergence of hypergeometric series, and the existence of fractal solutions in field theory. These findings suggest significant implications for quantum gravity, gauge theories, and the study of multifractal geometries in spacetime. The theoretical framework is supported by numerical simulations that demonstrate its robustness in field propagation over recursive layers. This paper formalizes the underlying principles of REHC, providing a rigorous mathematical structure for future research applications, including potential extensions to quantum field theory and cosmology. The results also reveal possible connections between fractal geometry and fundamental theories of nature.

The calculations of the mixture design of concrete have been widely performed according to the compressive strength or tensile strength. However, a cracked concrete/reinforced concrete structure can only be simulated by using the principles of fracture mechanics. The purpose of this study is to obtain certain expressions based on the properties of the fresh concrete and the fracture toughness of concrete, which is the fundamental parameter in analysis of the cracked structures. In accordance with this aim, the concrete mixture design method with the monogram proposed by Monteiro et al. for cement-based materials was utilized. Accordingly, 28 sets of batches with different slump values, cement contents, and water/cement ratios were cast to obtain this monogram. Fracture toughness tests on the notched beams and wedgesplitting (WS) specimens, and compression and splitting tests on cubes were conducted for hardened concrete. The fracture toughness test results were analyzed according to the effective crack model (ECM) in concrete fracture. Consequently, a mix design approach with a monogram was proposed to design according to the fracture mechanics of concrete. Furthermore, an approach based on the WS test was initially suggested to determine the fracture toughness of concrete for the ECM, which was essentially based on beams.

The experimental investigations on fracture mechanics of cement-based materials until 1970s indicated that classical linear elastic fracture mechanics (LEFM) is invalid for quasibrittle materials such as concrete. This inapplicability of LEFM is due to existence of an inelastic zone with large scale and full cracks in front of the main crack tip in concrete. This so-called fracture process zone (FPZ) is ignored by LEFM. Consequently, several investigators have developed non-linear fracture mechanics approaches to describe failure of concrete/reinforced concrete structures. Deterministic size effect laws among these non-linear approaches, for instance size effect law (SEL) by Bazant (1984), suggest that size effect on strength is primarily related to a relatively large FPZ in concrete. One of the main requirements in this law is the need to test samples, which are geometrically similar and made of the same material, and which must provide a minimum size range=1:4. The split-tension t...

The aim of this study is to predict formulas based on the Abrams&#39; Law between fracture parameters of concrete and w/c. Therefore, a series of three-point bend test on specimens were performed. The beams were made from mixes with water/cement ratios varying in the range of 0.34-0.85. The fracture parameters for each mix were calculated according to a popular fracture mechanics approach — two-parameter model. The present experimental data indicate that the fracture parameters of two-parameter model are inversely proportional to w/c ratios. In conclusion, the present test results are in agreement with the Abrams&#39; Law.

ABSTRACTMany non‐linear fracture models have been proposed by design codes and investigators to determine fracture parameters of cement‐based materials. To characterise failure of concrete structures, the effective crack model (ECM) needs two fracture parameters: the effective crack length ae and the critical stress intensity factor . Nevertheless, ECM requires a closed‐loop testing system and the calculation of ae needs considerable computational effort. For this reason, ECM is simulated with an artificial neural network (ANN) in this study. The main benefit of using an ANN approach is that the network is built directly on experimental data by using the self‐organizing capabilities of the ANN. The presented fracture model was developed by utilising 464 noisy test data taken from the literature, which were obtained via different test methods in different laboratories. The results of an ANN‐based ECM look viable and very promising.

The results of He et al. (1995) for the Double Cleavage Drilled Compression (DCDC) specimen are extended to cover the case where both the hole and crack are offset from the centerline of the specimen. The effect of the thickness of an adhesive layer on the value of the energy release is also investigated. The applicability of the results to experimental studies is presented.

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Clay minerals deposits, which include, kaolin, ball-clay, fireclay and zircon, were investigated and used in fabrication of ceramic floor tiles. X-ray diffractometer (XRD-6100, Japan), was used to examine the various compositions and structures of the clay samples. 2000 grams of 0.005 mm grain size of each sample were homogeneously mixed into dough, compressed in metallic mould of 12 mm × 36 mm dimension, and allowed to dry for about 5 hours. Kiln draught oven, at 1200°C was set for glazing and firing of the moulded tiles, to ensure glossy appearance, smoothness and improved strength. XRD test showed higher content of alumina (Al 2 O 3) and Silicon (iv) oxide (SiO 2) in all the clay samples. The percentage composition of Critobalite, Diphosphorus trioxide (P 2 O 3), Potassium Oxide (K 2 O) and Sodium Oxide (Na 2 O), were reasons for their excellent workability, improved mechanical and rheological properties of ceramics floor-tiles. Water absorption, chemical resistance, shrinkage properties of the different ceramic tiles were compare to some commercial products. This investigation had shown that locally available clay minerals could be fully integrated into ceramic industries to reduce cost of ceramic importation and create job opportunities for youths.

A Hookean material containing an increasing number of non-interacting microcracks is studied from the aspect of continuum thermodynamics. Rectilinear microcracks in a two-dimensional body are examined. The former model by Basista ( ) is enhanced to describe the response of microcracks to compression. Microcrack densities introduced here enter into the formulation of continuum thermodynamics as internal variables. The strong physical foundation of these internal variables makes them more attractive quantities for damage mechanics than variable damage, the physical background of which is sometimes unclear. The model is coded as an Abaqus VUMAT subroutine and applied to the creep of ice.

Damage that might originate from climate fluctuations can be observed on decorated oak wooden panels in historical Dutch cabinets and panel paintings. A thorough analysis of the damage mechanisms is needed to obtain a comprehensive understanding of the causes of damage and to develop sustainable conservation strategies. For this purpose, the combined experimental and numerical characterisation of the fracture behaviour of historic and new oak wood is studied. Three point-bending tests are performed, and the measured failure responses and fracture paths are compared against results computed with a finite element model, in which discrete fracture behaviour is simulated with an interface damage model. The experimental and numerical results are in good agreement. The experiments show a quasi-brittle fracture response for the oldest samples and a more brittle fracture response for the new samples. In addition, the strength required for crack initiation along a radial-longitudinal fracture plane is higher than for a tangential-longitudinal fracture plane and the strength depends on the specimen size. Photographs and scanning electron microscopy photos illustrate that fibre bridging is more apparent for the oldest samples, and that the location of crack initiation is set by geometrical imperfections. Moreover, differences in density characterize the crack propagation path.

Aim :The aim of the study is to compare immediate weight bearing with below-knee cast or immobilization with plaster splint in 6 weeks in patients after operative treatment for ankle bimalleolar fractures.Methods :Fifty-three patients with ankle bimalleolar fractures were treated operatively in 2005 to 2010 and then were randomly allocated to two groups. Immediately weight bearing in a below-knee cast (26 patients) and immobilization in a plaster splint for the first six postoperative weeks (27 patients). A mean age 37.9 (min 17; max 72). An average follow-up 26.1 months. (min 14; max 55). All fractures were classified with Lauge-Hansen classification. Functional results of both groups were evaluated with AOFAS for the postoperative one year after surgical treatment.Results :According to the AOFAS scoring system, results were excellent and good in 17 patients in group 1. On the other hand, results were excellent and good in 14 patients in group 2.Conclusion :As a result we think tha...

The fracture performance of rubberised bitumen in addition to one pre-treated with a Warm Mix Additive (Sasobit ® ) was investigated using different test methods measuring different damage mechanisms. Two Recycled Tyre Rubber (RTR) modifiers together with two base binders were blended in the laboratory to produce various combinations of Recycled Tyre Rubber Modified Bitumens (RTR-MBs). The first RTR is a standard recycled polymer derived from discarded truck and passenger car tyres by ambient grinding. The second RTR consists of 100% recycled truck tyres derived by cryogenic grinding and pre-treated with special oil and WMA to allow further decrease of asphalt mixture production temperatures. A fracture mechanics testing approach was used for evaluating the binder fatigue resistance; consisting of the double-edge-notched tension (DENT) test. The critical tip opening displacement (CTOD) obtained from the DENT test was used for fracture characterization of the binders within the ductile failure region. The study applied the partitioning concept of the total energy of bituminous binders to have a more reliable parameter that could be independent of the stress state of the ligament. The results show that generally the addition of RTR improves the fracture properties of binders indicating better fatigue performance. Pre-treatment with Sasobit ® makes the materials more brittle and hence more susceptible to fracture.

We present a unified mathematical framework that redefines the foundation of prime number theory and the Riemann Hypothesis through additive symmetry and interference. We construct a zeta-like function (Zeta hat of s) from a deterministic subset of primes called root-primes, generated via non-overlapping additive cycles based on the integers 1, 2, and 3. Built on a six-axiom system, this approach avoids analytic continuation and instead defines (Zeta hat of s) using a root-prime Euler product. The function exhibits convergence and zero alignment on the critical line ℜ(s) = 1/2, mimicking the classical zeta function through constructive arithmetic rules. We extend the model with two additional product forms-an inclusion-exclusion expansion and a cycle-encoded additive product-deepening insight into the origin of prime interference. The emergence of the Growth Mean G = 1.5, arising from additive triplets and modified gravitational structure, links number theory with wave mechanics and physics. Drawing on Laplace, Gödel, and de Broglie-Bohm, we show that randomness in prime distribution and zero placement is illusory, revealing an underlying deterministic order. Our findings suggest that the Riemann Hypothesis is not a conjecture, but a structural consequence of arithmetic interference and recursive symmetry.

The Extended Finite Element Method (XFEM) is a leading computational approach for studying crack growth in rocks, as it can effectively model complex crack paths and discontinuities without the need for re-meshing. In this context, XFEM is particularly well-suited for simulating the development of hydraulic fractures. XFEM is employed to investigate crack initiation, propagation, and aperture size in rock formations, with validation using a Boundary Element Method (BEM)-based approach. Three scenarios are analyzed for crack orientation and interaction in: single cracks at 0, 15, 30, and 60 degrees; crack displacement behavior at 15 and 60 degrees; multiple cracks at 60 and 120 degrees. Displacement in the vertical direction (U2) and stress distribution around the crack tip in the S22 direction are examined to understand fracture mechanics parameters. The findings highlight that crack at higher angles, such as 120 degree, exhibit more straightforward propagation, while those at or beyond 90 degree often require additional stress to continue growing. The comparison between XFEM and BEM results confirms the reliability of the numerical approach, demonstrating strong agreement in predicting fracture behavior in rock materials. The results provide deeper insights into fracture evolution, stress intensity factors, and fracture toughness in geological media. These simulations advance computational fracture mechanics, contributing to optimizing hydraulic fracturing techniques for improved efficiency and safety in subsurface formations. This study is limited to 2D geometries and isotropic materials, potentially missing 3D heterogeneous subsurface complexities. Future work could explore 3D models, anisotropy, and fluid pressure/thermal effects to improve crack growth predictions. Keywords: Extended finite element method, Hydraulic fracturing, Crack orientation and growth, Boundary element method, Rock fracture mechanics

Os acos inoxidaveis duplex (AIDs) sao constituidos por uma mistura de ferrita (CCC) e austenita (CFC) em fracoes volumetricas aproximadamente iguais. Os primeiros acos inoxidaveis duplex (AIDs) apresentavam baixa ductilidade e fragilidade, hoje sao amplamente empregados na industria petroquimica, de papel e celulose e na construcao civil, apresentando boas propriedades mecânicas e elevada resistencia a corrosao. O aco inoxidavel lean duplex UNS S32304, estudado neste trabalho, apresenta um custo inferior em relacao a outros acos duplex devido a substituicao parcial do niquel por nitrogenio como elemento gamageneo. Na soldagem dos acos inoxidaveis duplex (AIDs), as propriedades do material desejado podem ser radicalmente alteradas por um processo que funde e reformula localmente parte da microestrutura. Neste trabalho, amostras do aco inoxidavel lean duplex (AILD), soldado utilizando os processos de soldagem GMAW, SMAW e FCAW e consumiveis com dois tipos de composicao quimica, 2209 (...

The use of ceramics components in gas turbines, cutting tools, and heat exchangers has been limited by the relatively low flaw tolerance of monolithic ceramics. The development of whisker-toughened ceramic composites offers the potential for considerable improvement in fracture toughness as well as strength. However, the variability of strength is still too high for the application of deterministic design approaches. This report reviews several phenomenological reliability theories proposed for this material system, and reports on the development of a public domain computer algorithm. This algorithm, when coupled with a general-purpose finite element program, predicts the fast fracture reliability of a structural component under multiaxial loading conditions.

The Small Punch (SP) test is an assay that promotes the mechanical characterization of materials with a minimum requirement of material to test. This virtue makes it highly employable and it is currently used by industries such as aeronautics and nuclear. In the field of evaluation of in-service components, the SP test is shown to be advantageous with respect to conventional or traditional mechanical characterization tests, and in the case of the seconds, the amount of material required makes the test prohibitive, due to the affection that is caused to the component at the time of subtracting the necessary material. In the case of evaluating a component that has already failed, it allows a mechanical characterization during the expert work, which in many cases due to the nature of the failure, would be impossible because of the unavailability of sufficient material.

We show that the lattice Boltzmann formalism can be used to describe wave propagation in a heterogeneous media, as well as solid-body-like systems and fracture propagation. Several fundamental properties of real fractures (such as propagation speed and transition between rough and smooth crack surfaces) are well captured by our approach.

Equal channel angular pressing (ECAP) is a forming procedure. The Equal Channel Angular Pressing is a hardening treatment with which ductile metals can be processed to refine their grain and sub-grain structure. This process enhances the mechanical strength of metals in terms of tensile strength, stress-controlled fatigue strength, and fatigue crack growth resistance. The Equal Channel Angular Pressing is a hardening treatment with which ductile metals can be processed to refine their grain and sub-grain structure. This process enhances the mechanical strength of metals in terms of tensile strength, stress-controlled fatigue strength, and fatigue crack growth resistance. In this review, underline some critical aspects that have to be more investigated.

Polymer concrete (PC) with suitable mechanical and chemical properties was prepared. The properties of PCs are dependent upon the type of resins and filler materials. This research paper presents an assessment of the chemical resistance of polymer concretes in various chemical compositions. Epoxy resin was used to fabricate PC samples. The sample blocks were exposed to hostile environment in strong acidic and alkali conditions. The loss of compressive strength of the samples exposed to corrosive environment was insignificant. The strength of corrosive environment had significant effect on the chemical resistance of the fabricated PC samples. A desired blend of the optimized chemical composition of epoxy was used and tested in all corrosive environments. These samples were successfully passed all the designed testing conditions.

One particular concern of both regulators and operators related to NPP lifetime is to keep a sufficient safety level as a function of time. This requirement is sometimes considered to be equivalent as keeping safety margins constant. However, the notion of safety margins has an important variety of meanings. This paper investigates various existing meanings encountered in different contexts: NULIFE discussions, structural engineering and more precisely the context of structural integrity assessments in the French nuclear industry. In that context, “safety margin” is a generic term that applies to every kind of analytical margin supposed to enhance the structural safety. The potential requirement to keep safety margins constant does not apply to every type of margin: even the safety factor may in some cases be turned into equivalent sets of factors. Finally, what is important is that the safety level has to remain unchanged; this reliability level should be evaluated through a reliab...