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As the shipbuilding industry has emerged from an extended recession, orders for high-value-added ships, such as LNG and ultra-large container ships, are increasing. For ultra-large container ships, high-strength, thick materials are applied. Because the possibility of brittle fracture increases owing to the application of thick steel plates, the related regulations of the International Association of Classification Societies have been strengthened to prevent brittle fracture. To secure brittle fracture stability, it is necessary to secure crack arrest toughness (Kca) through large ESSO experiments or to secure a crack arrest temperature (CAT) value. Because large-scale experiments require considerable costs and efforts, efforts have increased to examine brittle fracture stability through small-scale tests. In the present study, a technology was developed to predict CAT with small specimens. The CAT prediction formula developed with small specimens makes it possible to accurately predict CAT using data obtained through large-scale experiments.

The localized compressive deformation (LCD) effect generated by an indentation process at the crack tip on the fatigue crack growth of the 7075-T651 aluminum alloy is reported. Eccentrically loaded single-edge crack tension specimens (ESE(T)) were pre-cracked at a crack length of about 20 mm by applying a constant amplitude fatigue loading. Subsequently, the LCD process was performed by using a semi-spherical indenter with a radius of 16 mm to compress the crack tip zone at different forces (5.0, 7.0, 12.5, 13.5, 15.5 kN), applied on the opposite surfaces of the specimens. The fatigue cracking process was continued on the compressed samples until an overall crack length of about 30 mm was obtained. The compressive load and the number of delayed cycles is discussed in terms of crack length and crack tip opening displacement (CTOD). A direct relationship between the compressive force induced by the LCD process and the delay of the crack propagation due to the crack arrest was observed. This effect became evident at a compressive force of 5.0 kN, where the crack propagation was arrested for about 9000 cycles in comparison with the non-LCD sample. However, when the force increased, the crack arrest also increased. The crack was considered to be completely arrested at a compressive load of 15.5 kN, since the crack did not grow after the application of more than 3 × 106 cycles.

To ensure the safety of supercritical CO2 pipelines and address the limitations of full-scale fracture tests, such as high risk and substantial investment, software for evaluating the crack arrest toughness of CO2 pipelines containing impurities was developed based on the Battelle Two-Curve Model (BTCM) in this study. The software is programmed in Python (v.3.12.4), with a graphical user interface (GUI) built using PyQt6 (v.6.10.0) and a three-tier architecture design. It integrates the resistance curve model and the decompression wave model. To determine the thermodynamic state of the fluid, a large property database covering pure components and various mixtures is embedded, incorporating state equations such as PR, HEOS, and GERG-2008. The software can generate pressure drop curves, decompression curves, and resistance curves. The pressure plateau can be quickly identified by examining the pressure drop curve. Whether the pipeline can achieve self-crack arrest can be rapidly judged by comparing the positional relationships between the decompression curve and the resistance curve. To verify the accuracy of the software’s calculation results, comparisons were conducted with previous decompression wave experimental data, full-scale burst test data of a CO2 pipeline, and the international HLP model. The calculation error of the software is within 10%. The development and application of this software provide a convenient, efficient, and accurate practical tool for the calculation of crack arrest toughness and crack arrest evaluation of supercritical CO2 pipelines.

Crack propagation within composite materials or along the interface of composite joints is a phenomenon that might result in catastrophic failure of a structure. When the factor of safety is involved in the integrity of a structure, fail-safe design becomes crucial by embedding failure-confining features. This article reviews the research work that has been carried out on such crack-arresting features (CAFs) for composite laminates, composite-to-composite joints and composite-to-metal joints. The methodology of descriptive–narrative systematic literature review was employed in order to present the state of the research in the field. Crack stopping along adhesively joined interfaces was the most common subject encountered in the literature, while other types of secondary bonding such as thermoplastic welding were quite limited. The types of the CAFs were mainly categorized by means of their integration into the structure, namely “production” and “post-production”. For each method reviewed, the common aspects of the CAFs in question are discussed as well as the outcome of the work.

Most of the rock mass in nature contains a large number of joints, faults and other defects, which make the rock mass have the characteristics of discontinuity and anisotropy, and easily lead to instability and failure of rock engineering. A great quantity of engineering practices show that the bolt has a significant supporting effect on jointed rock mass. Therefore, it is of great significance to study the deformation and failure characteristics of jointed rock mass and the crack arrest effect of bolt for the safety and stability of engineering. A reasonable numerical model of bolted rock samples with non-persistent joints is established by using a three-dimensional Particle Flow Code (PFC) based on the laboratory rock specimens, and the uniaxial compression numerical test is carried out. The results indicate that (1) the numerical simulation results are in good agreement with the laboratory test results, and the variation trend of strength is basically consistent; (2) the different joint angles and anchorage angles result in variations in the mechanical properties of bolted specimens with non-persistent joints; (3) the joint angle has a significant effect on the failure mode of the specimen; (4) the existence of bolts can effectively limit the initiation and propagation process of micro-cracks, and greatly improve the mechanical properties of the specimen containing non-persistent joints.

Traditionally, the stress intensity factor (SIF) is solely focused on in the fracture analyses of stiffened plate, while the T-stress is usually ignored. However, the fracture toughness is influenced by T-stress and the effects need to be studied. By means of three-dimensional finite element method, the characteristics of mode I SIF and in-plane T-stress are investigated in the double symmetrical central stiffened plate (DSC-SP). Then the fracture toughness is corrected with in-plane T-stress based on the two-parameter model in the R6 assessment procedure. Lastly, the curves of corrected fracture toughness and crack arrest effect are obtained in the stiffened plate. The results show that the T-stress is dependent on the size and integrity of the stiffener, and has significant effects on the fracture toughness of stiffened plate. Compared with the traditional estimation of the crack arrest effect of the stiffener, the evaluation is more reasonable when the influences of in-plane T-stress are taken into account.

Temperature gradient type ESSO test is one of the most popular test methods for evaluating the brittle crack arrest toughness, K c a . However, test conditions which are specimen shape, tab plate shape, applied stress and temperature gradient affect K c a . This document reports effects of specimen geometries that are specimen width, tab plate length, tab plate thickness and tab plate width on K c a evaluation. In addition, effects of applied stress and temperature gradient have also been investigated. Temperature gradient type ESSO tests are conducted at three different steel mills in Japan. Then, test conditions were varied and test results were compared. In the result, influence range of effect specimen width, tab plate thickness, applied stress and temperature gradient were demonstrated. The applicable range of specimen geometry, applied stress and temperature gradient were clarified and implemented to the brittle crack arrest standard.

Pipeline transportation is the most economical and reasonable way to transport natural gas. However, there are still some technical problems in high grade gas pipeline, in which fracture control is one of the key problems. The ductile fracture for long-range expansion is the most destructive failure mode of high pressure gas pipeline. In this study, the determination and prediction methods of crack arrest toughness of high grade (X80 and above) pipe line steels were introduced. Their application range, advantages and disadvantages were analyzed. The results showed that the toughness of X80 pipe line steel can meet the needs of the pipeline crack arrest requirements. It is difficult for the ultra-high-grade (X90 and above) pipe line steel to arrest crack by their own toughness. Therefore, the crack arrester should be installed. This paper introduced the crack arrest principle, advantages and disadvantages of various kinds of crack arresters.

The dual-horizon peridynamics (DH-PD) model is proposed to investigate the damage behavior of cracked structures in this paper. In the DH-PD formulation, the horizons are differentiated between how a material point receives and exerts forces on other material points. Based on this concept, the model takes unbalanced interactions among material points of varying horizon sizes into account, and satisfies both linear momentum balance and angular momentum balance. Using this model, the damage behavior simulations of cracked plates under tension were carried out using the model. The results show that the crack propagation patterns obtained are in good agreement with experimental results. Further research on the crack arrestor stiffened plate damage behavior shows that the crack arrester can effectively inhibit crack propagation. The parametric study involving crack-arresting stiffener location and stiffener’s relative stiffness is given. The simulation results show that the crack growth rate decreases as the stiffener’s relative stiffness increases. It is also shown that the crack-arresting effectiveness is significantly enhanced as the distance between the stiffener and the crack tip decreases. When the distance between the stiffener and the crack tip is reduced from 0.058 m to 0.042 m, the crack propagation rate decreases by 44.8%. The DH-PD model provides a more accurate and robust computational framework for the numerical simulation of fracture and crack arrest in cracked structures involving multi-scale and multi-material contexts, thereby further expanding the application scope of computational mechanics.

Graphene-based films with high toughness have many promising applications, especially for flexible energy storage and portable electrical devices. Achieving such high-toughness films, however, remains a challenge. The conventional mechanisms for improving toughness are crack arrest or plastic deformation. Herein we demonstrate black phosphorus (BP) functionalized graphene films with record toughness by combining crack arrest and plastic deformation. The formation of covalent bonding P-O-C between BP and graphene oxide (GO) nanosheets not only reduces the voids of GO film but also improves the alignment degree of GO nanosheets, resulting in high compactness of the GO film. After further chemical reduction and π-π stacking interactions by conjugated molecules, the alignment degree of rGO nanosheets was further improved, and the voids in lamellar graphene film were also further reduced. Then, the compactness of the resultant graphene films and the alignment degree of reduced graphene oxide nanosheets are further improved. The toughness of the graphene film reaches as high as ∼51.8 MJ m−3, the highest recorded to date. In situ Raman spectra and molecular dynamics simulations reveal that the record toughness is due to synergistic interactions of lubrication of BP nanosheets, P-O-C covalent bonding, and π-π stacking interactions in the resultant graphene films. Our tough black phosphorus functionalized graphene films with high tensile strength and excellent conductivity also exhibit high ambient stability and electromagnetic shielding performance. Furthermore, a supercapacitor based on the tough films demonstrated high performance and remarkable flexibility.