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In structural applications, catastrophic failure caused by fatigue occurs with more frequency because usually polymers are chosen when reduction in weight is necessary and overload is applied on it. In this study fatigue, crack growth at a humid, and very low temperature in a transparent unsaturated polyester resin has been investigated. The tests were conducted at a constant applied load ratio R = 0.1 using two different crack to width ratios (a/W) of 0.2 and 0.35 at room temperature and −60 °C. Polyester resin specimens are fabricated. The test used for the experiments is ASTM Standard D647 under tension–tension loading. The experimental results have been expressed in terms of Paris Law parameters. The fatigue crack results show that the fatigue resistance increases with decreasing a/w. It also shows that it increases with decreasing temperature up to −60 °C as the material becomes stiffer at the extremely low temperature and the polymer matric particles were much less mobile and ductile and discovered that low temperature has a positive influence on the strength of composites. The dominant failure mode was a polymer matrix -tear failure that was driven by a crack in the x-direction starts with the pre-crack in the case of a/w = 0.35 and it was slow enough in a/w = 0.2 because of the high energy of bonding and networking through the polymer matrix. The results proved that there is no through-the-thickness crack propagation due to fatigue in the polyester matrix.

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries, transport vehicles, and in several other applications. Excessive vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous accidents. So, there is a need for perceiving the dynamic nature and identifying the faults for the safe, smooth and effective operation of machines. This paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor balancing. Active magnetic bearing (AMB) misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment cases. Additional trial misalignments are provided in addition to the unknown misalignments of the residual misalignment case. For the execution of this methodology, the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically developed. The offset discs result in the gyroscopic effect at high rotor speeds. Equations of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions. A fast Fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and force-current stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification algorithm. Identified values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown misalignments. Testing of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness and robustness. The algorithm is found to be exhibiting excellent.

To reveal the damage characteristics and catastrophic failure mechanism of coal rock caused by gas adsorption, physical tests and theoretical methods are employed. The results show that adsorption swelling can damage coal rock, which can be distinguished by fractal dimension. A fitting relationship between the adsorption damage and fractal dimension is proposed by experimental testing and theoretical analysis. High gas adsorption pressure proves to be the dominant factor that leads to coal failure softening and gas outburst disasters. Three main parameters concerning adsorption damage include the change rate of released energy density, the transition difference in the post-peak acoustic emission (AE) b value and the change rate of cumulative AE energy. Results show that all the three parameters present a step-type decreasing change with the increase in fractal dimension, and the fractal dimension shows a linear relationship within the same failure mode. Finally, a method is proposed to evaluate coal rock disaster transformation, based on the aforementioned three main parameters of adsorption damage.

This chapter presents a new design method for considering the bracing effect of sheathing boards that are attached to CFS (cold-formed steel) structural members. It also presents a detailed summary of history, development, and flaws of the available sheathing braced design guidelines of the American Iron and Steel Institute. Previous investigations have shown that the current American Iron and Steel Institute (AISI) design specification for sheathing bracing design of CFS wall panels is unconservative (design predictions>experimental strength) due to exaggerated sheathing stiffnesses calculated from ideal loading conditions rather than worst-case loading conditions. Therefore a new design method is suggested based on the performance (strength and stiffness) of the individual sheathing-fastener connections. The current test setup of the AISI is improved to simulate realistic failure modes of the sheathing-fastener connections. The test results revealed: (1) the prominent influence of tensile modulus of the sheathing board and the geometric dimensions of the CFS stud (lever arm), (2) the sudden and catastrophic failure modes and they should be considered in the form of coefficients in the design expressions to prevent an unsafe design, and (3) the sheathing thickness did not influence the performance of the sheathing board (strength, stiffness, and failure mode). Based on test results, new expressions are formulated to predict the stiffness and strength of the individual sheathing-fastener connections. Finally, the effectiveness of the proposed simplified design method is illustrated by a design example, which quantifies the benefit of adopting this method in AISI design guidelines.

Bioinspired structures can attain mechanical properties unseen in conventional artificial materials. Specifically, the introduction of a cellular structure with a precisely designed distribution of cells, cell sizes, and cell walls is expected to enhance the mechanical response. Polylactic acid (PLA) is a biodegradable polymer produced from renewable resources with very interesting properties and good three-dimensional (3D) printing processability. However, its embrittlement during ageing at room temperature after a very short period of time (a few hours) significantly reduces its usability for advanced applications. Intense effort has been invested in improving its toughness via composition modification. However, this approach can worsen some other properties, make processing more difficult, and increase the carbon footprint. Therefore, fused deposition modelling (FDM) 3D printing was used to manufacture porous bamboo-inspired structures of unmodified PLA. The toughening of PLA solely by the pore gradient, which controlled the energy dissipation mechanism, was introduced for the first time. Improvement of the ductility and work at break was observed especially for notched specimens. Prevention of catastrophic failure could enable the use of gradient porous materials in structural components. The fundamental relationships and practical hints resulting from the work provide a foundation for the future design of toughened 3D printed structures.

Current research realize to develop a safer, lighter and higher energy absorbing fully thermoplastic (polypropylene fibres and acrylic Elium resin) and hybrid composite helmets (polypropylene/carbon hybrid and Elium resin) and perform the CPSC 1203 certification tests on different anvils. The failure and energy absorption mechanisms were studied and compared with widely used polycarbonate helmets (PC/EPS) and the composite shells manufactured with epoxy resin. The fully thermoplastic and hybrid composite shells have shown up to 65% of absorbed energy while the polycarbonate shells have absorbed a maximum of 13% of the absorbed energy. The usage of composite shells has lead to minimal energy transfer to the foam which is directly attached to the human head and provided improved safety. The high-speed camera has shown clear deformation of the thermoplastic composite shell owing to the ductile behaviour while the catastrophic failure with significant cracks was observed in the Epoxy-based composite shell. Considering the head injury criteria, the PC/EPS helmet showed the highest fatality rate (6%) when impacted on the flat anvil. The usage of fully thermoplastic and hybrid composite shell reduces the probability of critical and fatal injury by around 40% and 60% respectively when compared to PC/EPS configuration.

This paper introduces new composite architectures using carbon and glass fibre-reinforced epoxy prepregs to achieve gradual failure under bending. The concept is based on a technique developed by the authors to design hybrid composites with gradual failure in tension combined with beam theory to identify and control the failure sequence of the plies in the layups. Two layups are designed based on standard ply thickness S-Glass and hybrid sub-laminates made out of intermediate and high modulus thin-ply carbon prepregs. The layups are tested under 4-point bending loading where a gradual failure alongside high values of flexural displacement are achieved. No catastrophic failure is observed throughout the whole loading process. The gradual layer-by-layer failure of the surface layers on the tensile side produces a brush-like appearance. Microscopy observations from interrupted tests verified fragmentation of the high-modulus carbon layer followed by gradual failure of the intermediate modulus carbon layer and delamination on the tensile side, as well as stable shear cracks of the high-modulus carbon layer on the compression side.

The present work investigates cellular materials that can be potentially used as a replacement of solid implants owing to their mechanical properties and biocompatibility. More specifically, titanium alloy (Ti6Al4V) cellular materials of three different topologies were considered to study the effect of the degree of irregularity. Cubic regular, cubic irregular and trabecular structures were manufactured using Laser based powder bed fusion (LB-PBF) process. The LB-PBF process had an impact on the strut thickness of the samples. Samples were subjected to micro computed tomography to understand the geometrical deviations and to use the actual geometry for finite element analysis. Mechanical properties such as Young's modulus and strength were derived from compression and tensile testing. The results indicate that the Young's modulus was between 6 and 17 GPa, which were closer to the values of human cortical bone. The finite element analysis results showed a good correlation with the tensile test results as well. Furthermore, Gibson–Ashby model is used to study the effect of cell topology on the structural behavior. The model indicated that the misalignment of nodes of cubic regular structures to form irregular structure, transformed the stretching dominated behavior of cubic structures to bending dominated behavior like trabecular structures. Finally, the regular structures appeared to be much more prone to catastrophic failure than irregular and trabecular structures. Both visual observation of experimental testing and FE analysis explained this difference as result of different modes and zones of failures.

We present a rare case of a patient who presented with complete and rapid wear-through of a ceramic femoral head through a polyethylene liner and titanium acetabular cup. In addition, this patient exhibited significantly elevated serum titanium ion levels, which may serve as a marker of severe metallosis in cases where the preoperative plain radiographs underestimate signs of periarticular metal debris. The unique findings of this case include the rapid (less than 1 year time) wear-through of the femoral head in interval radiographs and the dramatic progression of metallosis and pelvic and femoral osteolysis that required both component revision. In addition, the markedly elevated titanium levels secondary to cup wear-through are also of interest and demonstrate a systemic manifestation of abrasive wear of a titanium alloy component. Keywords: Total hip arthroplasty, Revision arthroplasty, Wear-through cup failure, Catastrophic failure, Osteolysis, Ceramic on poly

Tibial baseplate fracture following primary total knee arthroplasty is a rare complication, particularly with modern implants and surgical techniques. This case details the first known report of mid-range follow-up catastrophic failure of a cementless modular, trabecular metal tibial baseplate. This failure highlights the importance of continued follow-up for novel implants, to include cementless knee arthroplasty designs, particularly if new symptoms arise or periarticular bone loss is identified on radiograph. Keywords: Total knee arthroplasty, Cementless baseplate fracture

This is the first report, to our knowledge, of a fracture, unrelated to trunnion corrosion, through the midneck of a well-fixed uncemented cobalt-chromium alloy femoral component that had been implanted via a total hip revision arthroplasty 25 years ago. Three years after a second revision for polyethylene wear, the patient noted an acute onset of pain in the left hip. There was no antecedent pain in the hip or thigh. Radiographs and intraoperative findings showed a well-fixed femoral component. Electron microscopic retrieval analysis showed intergranular material cracks. Revision of the femoral component was performed with an extended trochanteric osteotomy. This fracture of the femoral component neck was likely related to metal fabrication techniques, and surveillance of this component may be warranted. Keywords: Femoral component neck fracture, Total hip arthroplasty, Revision, Catastrophic failure

The use of carbon fiber reinforced implants to address distal femur fractures has gained in popularity due to their favorable mechanical characteristics and potential for improved healing. The failure of metal locked plates for this application has been widely reported. Here is presented a novel case of early failure of a carbon fiber reinforced polyetheretherketone (PEEK) plate applied for a distal femur fracture. This is the first known report of failure of a carbon fiber reinforced distal femur plate in a patient with a traumatic fracture. Due to the radiolucent characteristics of the plate, the failure was not immediately recognized. While there may be advantages to these plates, early catastrophic failure can still occur.

peer-reviewed Elastic boundary conditions play an important role in the buckling analysis of cylinders under compressive loading. These structures are used widely in aerospace applications and are highly sensitive to geometrical, material, loading, and boundary imperfections. In fact, the presence of these imperfections can lead to catastrophic failure. In 1968, NASA reported relations for obtaining the Knockdown Factor (KDF) based on an empirical method that is valid for isotropic and orthotropic materials; however, these relations do not consider the effect of elastic boundaries that can lead to highly conservative values of KDF. In design practice, a universal KDF of 0.65 has been used for recent designs by NASA, which may not be applicable to new types of structural configuration with different loading and boundary conditions. Therefore, there is a need for robust design factors for future designs which reduce the dependency on testing during preliminary design phases and speeds up the product development process. The availability of up‐to‐date and different KDF expressions for different structural configurations would help engineers to design lighter structures with improved load carrying capacity and reliability. The main objective of this work is to identify the buckling load sensitivity of cylindrical shells due to their boundary conditions and develop KDF relations considering elastic boundaries. To achieve this goal, the effect of axial, radial and tangential support stiffness on a quasi‐isotropic cylinder under axial compression is investigated. A data‐driven design approach is used to develop new KDF empirical relations for a quasi‐isotropic cylinder on different elastic foundations. The accuracy of these relations is within 5% for any elastic foundation considered.

Corrosion begins and increases over time, and in most cases, is hidden from view either inside a component such as a pipe or under a surface covering such as thermal insulation or concrete. Unfortunately, corrosion does not grow predictably. The present practice is to estimate a period of time over which corrosion will not cause a catastrophic failure and conduct an inspection to measure remaining wall thickness at specific intervals. This is usually done by marking certain areas on the component and attempting to collect data at the same location each time so that any changes in the component wall can be detected. This approach sounds like a logical one, but many times data are collected at specific spatial locations—for example, on 50-mm centers. There is no guarantee that the corrosion effect is occurring at one of the sites where data are collected. In fact, there can be a situation where a throughwall corrosion pit can grow next to a region that is being periodically inspected and the defect never detected. So, this type of process has uncertainties and can lead to unexpected failure.

A computational scheme to predict stiffness and strength of carbon nanostructures under various loading modes is reviewed and presented here. The prediction method is based on combined molecular mechanics and molecular dynamics simulations to search a global energy minimum at a given loading level with a preset temperature tolerance. The computational method has been applied to various carbon nanostructures including carbon nanotubes (CNTs), graphene, fused CNTs with defects, CNT–graphene junctioned nanostructures, and pillared graphene structures. In all these cases, the maximum stresses and strains at failure of these carbon nanostructures, as well as their critical failure modes related to the atomic structures including the mechanisms that lead to the catastrophic failure, are discussed in detail.

Corrosion of metals and alloys is a prime concern for different industries which results in structural deterioration due to environment, temperature, and many other factors. It can affect the life cycle of different equipment and pipelines and ultimately causes leakage, environmental pollution, and product loss. Sometimes, total loss of the structure is very less, but localized rate of attack is very fast which can cause catastrophic failure. In this chapter, we have discussed different metals and alloys, different corrosion types and their protection approaches, mechanical properties of metals and alloys, fabrication routes, and applications in different fields.

Self-healing materials are polymers, metals, ceramics, and their composites that when damaged by an operational use has the ability to fully or partially recover its original set of properties. Self-healing is a bioinspired technology which can heal micro- or nanolevel cracks generated in polymeric composites without any external interventions. In the present scenario, fiber-reinforced polymer (FRP) composites are being used in wide range of applications such as automobile, aerospace, energy, construction, and sporting equipment applications because of their high strength and stiffness-to-weight ratio, excellent corrosion resistance, and high thermal stability. Delamination occurring between the interply region and poor fracture toughness of matrix is the main failure mode occurring in FRP composites. Delamination of FRP composites occurs due to micro- or nanolevel cracks generated during in service period which propagates and finally led to catastrophic failure of the material. The cracks are hardly detectable and can be repaired. Therefore a huge demand is originated for self-healing of the micro- or nanolevel cracks generated in FRP-laminated composites at their nascent stage where repairing is too much challengeable.

The following case demonstrates an example of a catastrophic failure of a dual mobility (DM) bearing used in the setting of a revision total hip arthroplasty for an acetabular component with an excessive abduction angle. Currently, in the literature, it has been demonstrated that DM bearings have decreased polyethylene wear at abduction angles up to 65°; however, this has only been shown in in vitro studies. To our knowledge, there have been no reports of in vivo DM bearings that have demonstrated these same results. In this case, a DM bearing was used in a revision surgery with a retained acetabular component that had an abduction angle of approximately 70°-75° which ultimately led to catastrophic polyethylene failure. Keywords: Dual mobility bearing, Polyethylene wear, Revision total hip arthroplasty, Increased abduction angle

Fractures of well-ingrown femoral components are a rare and often challenging complication after revision total hip arthroplasty. Prior series have documented catastrophic failure at the modular junction of revision femoral components. However, to the authors' knowledge, there has been only 1 report of a mid-stem fracture of a modular tapered revision stem. The present article reports 2 cases of fatigue fractures (14 months and 10 years after implantation) of a tapered modular revision stem. It presents the results of the fracture surface analysis, discusses the etiology of failure, and presents the authors' recommendations on how to best avoid this complication. Keywords: Stem fracture, Tapered, Removal technique, Breakage, Failure

The magnetic orientation of steel fibres in transparent silicone oil and in fresh, self-compacting concrete (SCC) beams is studied experimentally. The effect of the generated fibre locations and orientations on the failure response of the SCC beams is determined by means of three-point bend tests. A relatively small coil was designed for the magnetic orientation of single and multiple fibres in the transparent silicone oil. The time required for orienting a single fibre was measured for a range of magnetic fluxes, which showed to strongly decrease with increasing magnetic field strength. The presence of gravel on the fibre orientation behaviour was considered in order to mimic the influence by a concrete aggregate, indicating that the gravel does not prevent rotations and chain formations of fibres. A larger coil was developed for the magnetic orientation of fibres in freshly casted SCC beams. The energy absorption capacity of SCC beams subjected to three-point bending scales approximately proportionally with the number of “well-oriented fibres” bridging the catastrophic failure crack, which emphasizes the importance of adequately orienting steel fibres with the magnetic orientation technique.

The Forced Draft Fan (FDF) blade in a 300 MW coal fired power plant that experienced catastrophic failure has been investigated. There were two main locations of the blade damage, namely damage at the root of the blade and the other one is at the third of the blade height. The FDF blade has been run for 5 years and before its failure, the FDF experienced high vibration (14 mm/s). The forced draft fan is an axial flow fan horizontally in front of the boiler and the fan is single stage. Visual inspection, metallographic analysis, chemical composition and hardness test were carried out to find the cause of the failure. It is concluded that the material of the blade is cast Al-Si alloy (A356.0) that fits the requirements for FDF blade application, the failure of the third of the blade height is owing to the external particles collide to the leading edge of the blades causing erosion and notch. That notch acted as initial crack. The failure at the root blade was caused by broken fragments of the others damaged blades entered in between casing (stator) and the blade (rotor) so they obstructed the blade rotation.

In our case study, we examine a case of catastrophic failure of a total hip arthroplasty acetabular component leading to complete central wear by the ceramic femoral head, requiring revision total hip arthroplasty. Despite subtle clinical findings, initial orthopaedic evaluation and treatment yielded a diagnosis of total hip arthroplasty dislocation. While a much more common phenomenon, the diagnosis led to futile initial attempts at closed reduction. Our index of suspicion must remain high to pick up on subtle, less common diagnoses we will encounter.

Coal bump refers to a sudden catastrophic failure of coal seam and usually can cause serious damages to underground mining facilities and staff. In this circumstance, this paper focuses on the recent achievements in the mechanism and prevention techniques of coal bumps over the past five years in China. Based on theoretical analysis, laboratory experiment, numerical simulation and field test, the characteristics of coal bumps occurrence in China's coal mines were described, and the difference between coal bumps and rockbursts was also discussed. In addition, three categories of coal bumps induced by “material failure” were introduced, i.e. hard roof, floor strata and tectonic structures, in which the mechanism of coal bumps induced by geological structures was analyzed. This involves the bump liability and microstructure effects on bump-prone coal failure, the mechanism of coal bumps in response to fault reactivation, island face mining or hard roof failure. Next, the achievements in the monitoring and controlling methods of coal bumps were reviewed. These methods involve the incorporated prediction system of micro-seismicity and mining-induced pressure, the distributed micro-seismic monitoring system, energy absorption support system, bolts with constant resistance and large elongation, and the “multi-stage” high-performance support. Finally, an optimal mining design is desirable for the purpose of coal bump mitigation.

The impact of polycarbonate products is a subject of critical interest in aviation and aerospace applications since high-velocity impact threats are unavoidable. For example, bird strikes often result in cracking or perforation of the windshield and canopy. For astronauts, the impact of space debris is an extremely severe threat since the impact energy of the debris with only 1 mm size could reach 71 J in space. Therefore, it is of great importance to understand and to accurately predict the impact responses and catastrophic failure of polycarbonate products.

Rapid global urbanisation and population growth is driving unprecedented levels of building construction, with the total worldwide floor area expected to almost double over the next 40 years. Since most of the structural material in a building exists within the floors, these present a significant opportunity for structural engineers to contribute to a more sustainable construction industry.This paper examines a novel flooring system of textile-reinforced concrete shells with a foamed concrete fill, which has the potential to halve the amount of materials in a building’s entire structure. A new design and geometry optimisation method is described, as well as the construction and testing of two prototypes; each 18mm thick, 2m in span and 200mm tall. These textile-reinforced concrete shells are unconventional in their low total depth, low reinforcement content and lack of rigid supports. Both were reinforced with AR-glass fibre textile and constructed using fine-grained concrete, however only one featured a foamed concrete fill. Each was tested to destruction under an asymmetric load. In both cases, a hinged collapse mechanism was formed rather than sudden catastrophic failure, with positive implications for safety and robustness.A non-linear finite element model was developed which replicated the observed behaviour well, including cracking patterns. Inaccuracies in geometry arising from the hand-made construction methods were measured and their structural impact was assessed and found to be small.The investigations confirm the strength, robustness and buildability of the structural system, and establish a reliable analysis method.

Avoidance of catastrophic failure of a large structure is to design the material’s microstructure in such a way as to render any crack that forms innocuous thereby raising the integrity of that structure. Predicting lifetime requires a knowledge of the state of damage in the material at all times up to the point of failure. The structural integrity (SI) of the structure depends upon a number of interacting factors: the criticality of the application; the accessibility for and ability to inspect vital parts and components; the intended use including load spectrum and time; the consequences of impact, fatigue, environment, temperature, and hostile environment; the nature of inherent flaws; the properties of the material system utilized; and it takes into account “human factors.” The SI of a composite structure embraces contributions from materials science and engineering; fabrication technology and processing science. This chapter seeks an overview of advanced composite materials in the 21st century; a perspective on designing composite structures having SI.

A simplified mathematical model representing the dynamic response of a tank containing a pressurized liquefied gas exposed to an external heat source, is presented. This scenario is of great practical interest in the process industry because it can result in the catastrophic failure of the tank with the explosive vaporization of the stored material (Boiling-Liquid Expanding-Vapour Explosion, BLEVE). The model has been validated against experimental data available in the literature and then applied to a number of reference cases, to assess the influence of the main parameters involved in the phenomenon on the evolution of the accident. This approach can be very helpful in various applications, such as risk analysis, where a large number of different scenarios must be simulated and/or the most critical conditions must be quickly identified. It has been found that the temperature of the tank wall in contact with the vapour phase is the most critical parameter. The time-to-failure of the tank is mainly affected by the received heat flux, while the time for the first opening of the pressure relief valve is very sensitive to both the initial storage temperature conditions and the heat input.

To match with requirements of service, heat treatment methods have been successfully applied to aluminium alloys for decades. However, like ferrous alloys, aluminium alloys are prone to dimensional defects and distortion during finishing processes due to the presence of residual stresses in the component. Such residual stresses are developed while obtaining strength by precipitation hardening. These stresses are sometimes beneficial. However, the degree of these stresses is to be kept at a minimum to prevent in-service accidents by catastrophic failure. Residual stresses can be relaxed by stress relaxation techniques. The most common techniques are mechanical working methods, which differs from ferrous alloys for which thermal methods provide greater relief.

Anisotropic mechanical behavior of cortical bone and its intrinsic hierarchical microstructure act as protective mechanisms to prevent catastrophic failure due to natural loading conditions; however, they increase the extent of complexity of a cutting process in the case of orthopedic surgery. Experimental results available in the literature suggest that bone tissue deforms significantly prior to the separation in the vicinity of the cutting zone, which is challenge to model because of large deformation and damage process. In addition, existing models of bone cutting do not account for material anisotropy or the effect of damage mechanisms. In this chapter, a novel smoothed particle hydrodynamic (SPH) domain embedded into a continuum finite element (FE) model (SPH + FE scheme) was developed to characterize anisotropic deformation and damage behavior of cortical bone under a cutting process. A set of tool-penetration experiments was performed in directions parallel and perpendicular to bone axis. Distinct deformation and damage mechanisms linked to different microstructure orientations were captured using a microlens high-speed camera. The FE model reflected adequately the experimental results and demonstrated a clear advantage in accounting for its anisotropy and damage mechanisms when modeling hard biological tissues such as cortical bone.

We investigate the mechanical behavior of 3D periodically architected metallic glass nanolattices, constructed from hollow beams of sputtered Zr-Ni-Al metallic glass. Nanolattices composed of beams with different wall thicknesses are fabricated by varying the sputter deposition time, resulting in nanolattices with median wall thicknesses of ∼88 nm, ∼57 nm, ∼38 nm, ∼30 nm, ∼20 nm, and ∼10 nm. Uniaxial compression experiments conducted inside a scanning electron microscope reveal a transition from brittle, catastrophic failure in thicker-walled nanolattices (median wall thicknesses of ∼88 and ∼57 nm) to deformable, gradual, layer-by-layer collapse in thinner-walled nanolattices (median wall thicknesses of ∼38 nm and less). As the nanolattice wall thickness is varied, large differences in deformability are manifested through the severity of strain bursts, nanolattice recovery after compression, and in-situ images obtained during compression experiments. We explain the brittle-to-deformable transition that occurs as the nanolattice wall thickness decreases in terms of the “smaller is more deformable” material size effect that arises in nano-sized metallic glasses. This work demonstrates that the nano-induced failure-suppression size effect that emerges in small-scale metallic glasses can be proliferated to larger-scale materials by the virtue of architecting.

Unidirectional composites under longitudinal tension develop damage through the accumulation and clustering of fibre–breaks, which may lead to catastrophic failure of an entire structure. This paper uses a hierarchical scaling law to predict the kinetics of fibre–breakage and its effect on the stress–strain response of composites under longitudinal tension; due to its analytical formulation based on the statistical analysis of hierarchical fibre–bundles, the scaling law predicts the response of composite bundles up to virtually any size in less than one second. Model predictions for the accumulation and clustering of fibre–breaks are successfully validated against experiments from the literature. These results show that the present model is a much more computationally–efficient alternative to other state–of–the–art models based on Monte–Carlo simulations, without sacrificing the accuracy of predictions when compared against experiments.

Variable frequency drives (VFDs) provide substantial energy savings and control for commercial and industrial process applications. Unfortunately, previously unanticipated bearing failures are occurring because modern VFDs induce a harmful voltage on the motor shaft. As the resulting current travels through motor bearings, it can cause catastrophic failure and costly downtime. Carefully chosen grounding technology is the answer.

Surface cracks commonly propagate in rotating machines due to cyclic loads. The propagation of these cracks in shafts is an important problem that can lead to catastrophic failure and put lives at risk. Although the majority of the works on cracked shafts consider that the shape of the front of the surface cracks is straight or almond, also sickle-shaped cracks can appear in shafts. In this study, we propose an expression that provides the value of the Stress Intensity Factor (SIF) of an open crack with sickle shape, located at the central section of a shaft, as a function of the relative depth of the crack, the shape factor and the relative position on the crack front. To this end, the SIF along the crack front has been determined through a 3D numerical analysis considering different elliptical geometries of the crack. To validate the expression, we have compared the obtained results with other solutions obtained by numerical approaches of the literature. It has been found that they are in good agreement. Finally, the sickle crack propagation has been analyzed using the expression for sickle cracks proposed and a developed algorithm based on the Paris Law. The authors would like to thank the Spanish Ministerio de Economía y Competitividad for the support for this work through the project DPI2013 45406 P.

With the improvement of integrated circuit technology, chips contain more and more functions. For airborne electronic hardware, the radiation effect poses more and more hidden dangers to the safety of aircraft. According to the current technological trends, in the next decade, if civil aircraft continues to use a large number of highly integrated electronic components and microprocessors, taking additional protective measures, then the average probability of catastrophic failure conditions caused by radiation-induced failure of aircraft hardware and software in the next decade will increase by at least 10 times. This will be a major risk to aviation safety. Therefore, the Single Event Effects problem needs to be taken into account at the Preliminary System Safety Assessment process at the beginning of the system design.

In Chapter 6 , the complexity of the California electricity system was discussed in some details. Complexity and the complex systems such as data, archives, information processing, and networks were not the only problem that led to a number of operating and policy decisions. Nonetheless, it contributed to both the forces urging the state to deregulate and to the catastrophic failure of the resultant deregulated system.

The use of porous cellular structures in bone tissue engineering can provide mechanical and biological environments closer to the host bone. However, poor internal architectural designs may lead to catastrophic failure. In this work, 192 open-porous cellular structures were fabricated using 3D printing (3DP) techniques. The mechanical and biological behavior of four 3D internal structures (octahedral, pillar octahedral, cubic and truncated octahedral) was investigated. It was found that the pillar octahedral shape has not only greater stiffness and strength under compression, shear and torsion but increased rate of pre-osteoblastic cell proliferation. We believe bone implants can be fabricated using 3DP techniques and their mechanical and biological performance can be tailored by modifying the internal architectures.

The aim of condition monitoring is to detect faults before a catastrophic failure occurs. Cracks in rotating shafts are especially critical. The present work studies vibration signals obtained from a rotating shaft under different crack depths and locations. Tests were performed in a rig called Rotokit at a steady state at different rotation speeds. Signals obtained are analyzed by means of energy using the Wavelet theory, specifically the Wavelet Packets Transform. Nine crack depths in the shafts were tested, from 4% to 50% of the shaft diameter. Previous related work showed good reliability for crack diagnosis using 3 x energy for cracks in the middle section. In the present work, previous results are compared to the obtained for a crack in a change of section at one side. In both crack locations, large changes in energy are observed at 3 x at high speeds. Energy levels at this harmonic were used for the inverse process of crack detection, and probability of detection curves were calculated by thresholding. Cracks with depths above 12% can be detected with reliability in the locations tested using this method. The authors would like to thankthe Spanish Government for financing through the projects RANKINE21 IDI-20101560 and MAQ-STATUS DPI2015-69325-C2-1-R.

In material science studies, it is often desired to know in advance the fracture toughness of a material, which is related to the released energy during its compact tension (CT) test to prevent catastrophic failure. In this paper, two frameworks are proposed for automatic model elicitation from experimental data to predict the fracture energy released during the CT test of X100 pipeline steel. The two models including an adaptive rule-based fuzzy modelling approach and a double-loop based neural network model, relate the load, crack mouth opening displacement (CMOD) and crack length to the released energies during this test. The relationship between how fracture is propagated and the fracture energy is further investigated in greater detail. To improve the performances of the models, a Gaussian Mixture Model (GMM)-based error compensation strategy which enables one monitor the error distributions of the predicted result is integrated in the model validation stage. This can help isolate the error distribution pattern and to establish the correlations with the predictions from the deterministic models. This is the first time a data-driven approach has been used in this fashion on an application that has conventionally been handled using finite element methods or physical models.

Engineering structures are often subjected to fatigue loads. Monitoring the process of fatigue crack propagation as well as estimating the remaining useful life (RUL) of a structure is thus essential to prevent catastrophic failure while minimizing earlier-than-required replacement. Autonomous, real-time, remote monitoring becomes possible with the use of smart piezoelectric transducers, alleviating the shortcomings of conventional nondestructive inspection techniques. For instance the electromechanical impedance (EMI) technique is known for its ability in damage detection and characterization. This chapter presents a series of investigative studies to evaluate the feasibility of fatigue crack monitoring and estimation of RUL using the EMI technique. Experimental tests were conducted to study the ability of EMI technique in monitoring fatigue crack in one-dimensional laboratory-sized aluminum beams subjected to mode I fatigue loading. The experimental results demonstrated that the EMI technique is very sensitive to monitoring fatigue crack propagation in all three stages. A proof-of-concept semianalytical damage model for fatigue life estimation has been developed by incorporating the linear elastic fracture mechanics theory into the finite element model. The prediction of the model matches closely with the experiment, suggesting the possibility of replacing costly experiment in future.

Failure of large storage tanks can be devastating owing to impact damage from the sudden release of a fluid wave. Fracture of a polypropylene tank along a weld seam was caused by faulty design, and the walls could not withstand the hydrostatic internal pressure. The tank breached a German standard DVS 2205 with walls built like a barrel rather than like a dam. A paint tank also failed suddenly from a welded joint due to faulty design. Sewage storage tanks were rotationally moulded in HDPE but collapsed due to external groundwater pressure. The walls were not reinforced and crept under pressure. A mancab and traffic cones failed by UV degradation and should have been protected with special additives. Battery cases exposed to strong sunlight also fractured due to UV degradation, which was concentrated at the weld line owing to a faulty heater. Catastrophic failure of a fibreglass tank was caused by poor design with walls incapable of supporting the load and a bund wall which hid the deformation in its short life. The polymer wall could not withstand the high temperatures of boiling water and crept under load. Spirally wound tank walls have improved the design of tanks for hazardous fluids, but in one case, the plastic base failed and caused an acid leak. It was caused by excessive trimming at a thermal weld followed by crack growth.

Polymers are used extensively in pipes and fittings owing to great corrosion resistance, but failures have occurred in PVC water mains. A broken PVC main flooded a factory and failure was caused by overload at a junction with a steel main. In turn the failure was caused by insertion of a new fitting and also by sinking of the foundation. Failures of rising PVC mains in developing countries occurred by poor solvent welding and poor adhesive, causing fatigue fractures. Poor workmanship caused several leaks in machined PVC equipment. There have been numerous disasters caused by fracture of gas pipes, often from poor fitment and faulty joints as well as poor foundations. Catastrophic failure in an ABS pipe for a compressed gas facility was likely caused by environmental stress cracking from oil residues rather than by fatigue. Acetal resin used in pipe fittings has failed due to brittle cracking caused by chlorine attack in potable water supplies. One such case involved a faulty moulding with fractures occurring on weld lines. Very extensive failures have occurred in the United States with hot water systems, causing failure of polybutene pipe as well as acetal fittings, and it is one of the largest class actions in legal history. Better polymers include cross-linked polyethylene.

The increased significance and value of the multi- and interdisciplinary failure analysis field arises from the benefits incurred in terms of insurance costs, quality improvement, and prevention or minimization of environmental and safety risks. Especially in the chemical industry sector, the preventive role of failure analysis is of paramount importance, since the criticality and risk of an unfolding failure event provides a potential of huge safety and/or environmental hazards (chemical accidents, explosions, environmental-type leakages, etc.). Progressive-type failures are considered as the most insidious damage mechanisms which are very often difficult to detect and predict. Aggressive service conditions prevailing in chemical process plants, such as elevated temperature and pressure and corrosive environments, stretch the safety operating limits of engineering materials and components at challenging levels of endurance and reliability. The current chapter presents the investigation methodology of characteristic failures of chemical and process plants’ components, based mainly on case history investigation approach. A brief introduction addresses the progressive failure modes, focusing mainly on creep and stress corrosion cracking (SCC) in special steel structural members. Next, the results of the investigation of two respective case histories are thoroughly analyzed and discussed. The evolution of creep damage is presented in the case of a steel pipe operating in a power plant together with the discussion of the influence of operation parameters. The SCC mechanism is addressed through the catastrophic failure of a stainless steel screen (grid) used in a naphtha production unit in petrochemical industry. Visual inspection, optical microscopy, and scanning electron microscopy coupled with energy dispersive X-ray microanalysis were used as the principal analytical techniques for the case history failure investigation.

Factory production rates are directly affected by how and when equipment maintenance is performed. Cost consequences can be expected when critical equipment has to be shut down for a major repair. Waiting for a catastrophic failure to occur is neither a safe nor profitable option. Therefore, safe and reliable factories schedule major offline maintenance intervals according to a specific plan that is related to experience-based equipment life cycle expectations. Their maintenance goal is to intervene with a predefined and obviously suitable course of preventive actions. Without this intervention a catastrophic failure will periodically shut down the manufacturing process or curtail factory production rates. The application of basic equipment reliability principles assists in extending the useful life of process equipment and helps the site to stay in control over the maintenance plan. A basic understanding of equipment reliability principles provides the background needed to understand and diagnose the causes for history's worst industrial disasters, which might also be detected in our own industrial processes. This knowledge of equipment reliability principles creates a sense of what can personally be done to prevent catastrophic process releases.