Energy bursts in fiber bundle models of composite materials

As a model of composite materials, a bundle of many fibers with stochastically distributed breaking thresholds for the individual fibers is considered. The bundle is loaded until complete failure to capture the failure scenario of composite materials under external load. The fibers are assumed to share the load equally, and to obey Hookean elasticity right up to the breaking point. We determine the distribution of bursts in which an amount of energy $E$ is released. The energy distribution follows asymptotically a universal power law $E^{-5/2}$, for any statistical distribution of fiber strengths. A similar power law dependence is found in some experimental acoustic emission studies of loaded composite materials.Comment: 5 pages, 4 fig

Failure avalanches in fiber bundles for discrete load increase

The statistics of burst avalanche sizes $n$ during failure processes in a fiber bundle follows a power law, $D(n)\sim n^{-\xi}$, for large avalanches. The exponent $\xi$ depends upon how the avalanches are provoked. While it is known that when the load on the bundle is increased in a continuous manner, the exponent takes the value $\xi=5/2$, we show that when the external load is increased in discrete and not too small steps, the exponent value $\xi=3$ is relevant. Our analytic treatment applies to bundles with a general probability distribution of the breakdown thresholds for the individual fibers. The pre-asymptotic size distribution of avalanches is also considered.Comment: 4 pages 2 figure

Breaking rate minimum predicts the collapse point of over-loaded materials

As a model of composite materials, we choose a bundle of fibers with stochastically distributed breaking thresholds for the individual fibers. the fibers are assumed to share the load equally and to obey Hookean elasticity right up to the breaking point. We study the evolution of the fiber breaking rate at a constant load in excess of the critical load. The analysis shows that the breaking rate reaches a minimum when the system is half-way from its complete collapse.Comment: 5 pages, 6 figures, submitted to Phys. Rev.

A Cellular Automaton Model of Damage

We investigate the role of equilibrium methods and stress transfer range in describing the process of damage. We find that equilibrium approaches are not applicable to the description of damage and the catastrophic failure mechanism if the stress transfer is short ranged. In the long range limit, equilibrium methods apply only if the healing mechanism associated with ruptured elements is instantaneous. Furthermore we find that the nature of the catastrophic failure depends strongly on the stress transfer range. Long range transfer systems have a failure mechanism that resembles nucleation. In short range stress transfer systems, the catastrophic failure is a continuous process that, in some respects, resembles a critical point.Comment: 11 pages, 11 figures (2 in color). Various corrections as recommended by referees. This is the final version for publication in Phys. Rev.

Shear stress fluctuations in the granular liquid and solid phases

We report on experimentally observed shear stress fluctuations in both granular solid and fluid states, showing that they are non-Gaussian at low shear rates, reflecting the predominance of correlated structures (force chains) in the solidlike phase, which also exhibit finite rigidity to shear. Peaks in the rigidity and the stress distribution's skewness indicate that a change to the force-bearing mechanism occurs at the transition to fluid behaviour, which, it is shown, can be predicted from the behaviour of the stress at lower shear rates. In the fluid state stress is Gaussian distributed, suggesting that the central limit theorem holds. The fibre bundle model with random load sharing effectively reproduces the stress distribution at the yield point and also exhibits the exponential stress distribution anticipated from extant work on stress propagation in granular materials.Comment: 11 pages, 3 figures, latex. Replacement adds journal reference and addresses referee comment

Introducing innovative technologies in higher education: An experience in using geographic information systems for the teaching‐learning process

In today's world, new technologies are being used for the teaching‐learning process in the classroom. Their use to support learning can provide significant advantages for the teaching‐learning process and have potential benefits for students, as many of these technologies are a part of the work life of many current professions. The aim of this study is to analyse the use of innovative technologies for engineering and science education after examining the data obtained from students in their learning process and experiences. The study has been focused on computational geographic information systems, which allow access to and management of large volumes of information and data, and on the assessment of this tool as a basis for a suitable methodology to enhance the teaching‐learning process, taking into account the great social impact of big data. The results allow identifying the main advantages, opportunities, and drawbacks of using these technological tools for educational purposes. Finally, a set of initiatives has been proposed to complement the teaching activity and to improve user experience in the educational field.This study was supported by the Spanish Research Agency and the European Regional Development Fund under project CloudDriver4Industry TIN2017‐89266‐R

Failure Processes in Elastic Fiber Bundles

The fiber bundle model describes a collection of elastic fibers under load. the fibers fail successively and for each failure, the load distribution among the surviving fibers change. Even though very simple, the model captures the essentials of failure processes in a large number of materials and settings. We present here a review of fiber bundle model with different load redistribution mechanism from the point of view of statistics and statistical physics rather than materials science, with a focus on concepts such as criticality, universality and fluctuations. We discuss the fiber bundle model as a tool for understanding phenomena such as creep, and fatigue, how it is used to describe the behavior of fiber reinforced composites as well as modelling e.g. network failure, traffic jams and earthquake dynamics.Comment: This article has been Editorially approved for publication in Reviews of Modern Physic