Three different experimental set-ups were employed in the investigation of the fracture strength of annealed float glass. These included four-point bending tests on three different specimen sizes, and quasi-static and dynamic pressure tests. The latter tests were conducted in a shock tube, i.e., a device that produces pressure loadings similar to that from a far-field blast event. The experimental work demonstrated that the fracture strength of glass varies largely within the same test set-up. It also revealed that the fracture strength and its scatter are dependent on the size of the specimen, the boundary conditions and the loading situation. By employing a newly proposed strength prediction model, which relies on the physical fracture behaviour of glass, the trends observed in the experiments were correctly recreated.

Bolt preload is one of the most significant parameters in bolted connections, which affects the static and fatigue performance of bolted connections. Traditional preload measuring methods give an estimation of the preload at the moment of tightening but cannot monitor preloading losses. In this investigation an initial proof of concept of a DIC based approach to relate bolt elongation to bolt preload is presented. Bolt elongation tests were performed to M16 bolts and a calibration method was proposed to obtain the bolt preload-elongation relationship for a given clamping length range.

The present article describes the methodology used to design and calibrate a 6-component balance. This balance is utilized in an instrumented bike measuring the forces applied on the handlebars. This instrumentation bike maps all riders induced loads. In the designing process, Finite Element Analysis was used. Calibrating the balance was done using the Least Square Regression Method which allows combining multiple loads during calibration and thus requires less samples. The balance operates with a maximum full scale error of 0.53%.

Studying the deformation and microstructure evolution for Ni-based single crystal alloys at high temperature has important effects on the design of turbine blades and disks. However, in-situ high temperature tests under scanning environment pose an important challenge for the current experimental conditions. In this paper, the resistance heating system was introduced in the high temperature fatigue experimental apparatus. The in-situ tensile test of 900°C was successfully carried out. The experimental results showed that the crack initiation was mainly caused by inclusion debonding. The fracture mode was mainly characterized by the connection of micro holes.

Fire‐testing of Textile Reinforced Concrete (TRC) is an interesting field in which quite limited research has been conducted so far. In this paper some preliminary tests are presented, where mortars used as binders are heated to 850 oC and their residual strength is tested, while the Ultrasonic Pulse Velocity (UPV) is also measured, before and after heating, and compared. Additionally, TRC specimens are subjected to flame exposure with a simple set‐up and the residual strength is also tested by flexural tests. It is concluded that even with simple set‐ups, interesting results can be obtained regarding the structural degradation of the material.

Historical masonry structures during the decades, were composed with a variety of brick and mortar types according to materials availability of each region and the desirable mechanical properties in each specific case. Different composition of mortars leads to another masonry behavior, and each one is suited for different structural purposes. A crucial aspect in damage evaluation of masonry structures is the analysis of long-term behavior which has a great influence on safety assessment of these structures. In this study, cement, hybrid lime cement, hydraulic lime and lime hydrate mortars were assembled with solid red clay bricks to compose four masonry walls of dimensions 515x376x90 mm. They were tested under cyclic compression loading. Acoustic Emission (AE) allowed in situ monitoring of damage progression. AE is a powerful non-destructive technique applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate a variety of characteristics during fracture propagation to obtain information on the criticality of the ongoing process. Specifically, analyzing and comparing AE parameters among the loading cycles of each wall specimen and among the different masonry compositions, an integrity assessment can be achieved. Furthermore, in each loading and unloading step, pulse velocity measurements were conducted using the AE apparatus in order to gain a velocity distribution mapping among the sensors. Each sensor was pulsed in turn, with all other sensors acting as receivers, generating a velocity matrix from one sensor to another. This provided an insight into the damage severity of masonry walls with the increasing number of loading cycles. This measurement was also necessary for refining AE source location accuracy by using either the horizontal or the vertical velocity. Two different cases were investigated. The use of one uniform velocity for the whole masonry wall and the assumption that the velocity differs in the two vertical directions due to the heterogeneity of the structure. These two cases result in differences in the quantity and the position of the localized events. Furthermore, applying direct ultrasonic pulse velocity measurements, in the direction of the width of masonry walls, another integrity investigation was feasible. The presented results further demonstrate the relationships between AE parameter-based analysis, velocity distribution and source location during cyclic compressive loading in masonry specimens. The identification of the nature of damage through the entire dataset of all sensor arrays provides a promising example for structural health monitoring applications on larger scale masonry specimens. As a conclusion, AE activity analysis proved to be a very efficient approach to evaluate fracture progress in masonry.

Damage leading to failure in concrete and related materials is a complex behavior. Whilst many numerical approaches are available for simulating the degradation of material strength, it is difficult to discriminate between these models experimentally in the high strain rate ballistic impact regime. An experimental method has been developed to determine when local material failure has occurred, and whether the failure can be classed as fracture or granular flow. This method is tested on Kolsky bar and ballistic impact experiments. Comparison with numerical simulations is presented.

Fatigue performance of additively manufactured (AM) components is still uncertain and inconsistent. Structural health monitoring (SHM) systems offer a solution to continuously monitor the structural integrity of a structure. The effective Structural Health Monitoring (eSHM) system is the first SHM principle developed with the principal purpose to monitor AM components. The eSHM principle exploits the design freedom offered by AM to integrate a capillary inside the component. The capillary is put under low vacuum and the pressure is monitored during the operation of the component. As-built AM surfaces report elevated surface roughness and are one of the principle causes of premature fatigue initiation and fatigue failure. The current study will investigate the effect of a chemical etching (CE) post-process on the capillary surface and evaluate its effect on the fatigue performance.

The trajectory of fatigue crack growth is influenced by many parameters and can be irregular due to changes in stress distribution or in material properties as the crack progresses. Images of the surface of a standardized test specimen can be used to visualize the crack trajectory in a non-destructive way. Accurately identifying the location of the crack tip, however, is challenging and requires devoted image postprocessing. In this respect, digital image correlation allows to obtain full field displacement and strain fields by analysing changes of digital images of the same sample at different stages of loading. This information can be used for the purpose of crack tip tracking. This paper presents a combined experimental-numerical study of detection and prediction of fatigue crack propagation path by means of digital image correlation (DIC) and the extended finite element method (X-FEM). Experimental validation and analyses are carried out on a modified C(T) specimen in which a curved crack trajectory is triggered by introducing mixed-mode (tension + shear) loading. The developed tools are used for validating an automated framework for crack propagation prediction.

This paper provides a study on mixed-mode fracture mechanics in thin-walled tube which is subjected to tension, shear and torsion loading. This type of loading causes an inclined crack to develop and generate a mixture of normal and shear stresses ahead of a crack tip. The stress state ahead of a crack tip is frequently based on mixed-mode type of interactions which designate the amplitude of the crack tip stresses. The analytical expressions for the stress intensity factors for mixed-mode I + II approach are presented. The Paris law for mixed-modes I + II has been discussed. Mixed-mode fracture mechanics is used with theoretical models to predict the path of crack growth when an inclined crack is subjected to a combination of mode I and mode II deformations. The torque at which crack propagation can be expected has been determined. The numerical calculations have been carried out by using MATLAB code. The results are good and could be useful for companies working with thin-walled circular tubes.