Joint Integrity Research Articles

A Drop-in High-Temperature Pb-Free Solder Paste that Outperforms High-Pb Pastes in Power Discrete Applications

Sn-based high-temperature lead-free (HTLF) solder pastes have been developed as a drop-in solution to replace the high-Pb solder pastes in power discrete applications. The pastes were designed to combine the merits of two constituent powders. A SnSb-based Ag/Cu-containing high temperature powder, with the melting temperature above 320° C, was designed to maintain a high-temperature performance. A Sn-rich SnAgCu-Sb powder, with a melting temperature around 228° C, was added to the paste to enhance wetting and improve joint ductility. In the design, the final joint will have the low-melting phase (the melting temperature >228o C) in a controllable quantity embedded into the high-melting SnSb matrix. HTLF-1, one of the designs, maintained the bond shear strength up to 15MPa, even around 290° C. Another design, HTLF-2, has a similar bond shear strength as Pb92.5/Sn5/Ag2.5 around 290° C, but exceeds substantially below 250° C. The power discrete components had been built with both HTLF solder pastes for both die-attach and clip-bond through the traditional high-Pb process, which demonstrated the drop-in processing compatibility. The components survived three additional SMT reflows (peak temperature of 260° C) and passed moisture sensitivity level 1. This confirmed that the maintained joint strength (comparable to or stronger than high-lead), helped to keep the joint integrity within the encapsulated components in the following SMT process, even with the controlled quantity of the melting phases above 228° C. Both HTLF solder pastes outperformed Pb92.5/Sn5/Ag2.5 in the resistance from drain to source when power is on (RDS(on)), even after 1000cycles of TCT (-55/175o C), which is attributed to the intrinsic lower electrical resistivity of Sn of both HTLF pastes. Microstructural observation had shown no corner cracks for both die-attach and clip-bond joints after TCT.

Microstructural Characterization of Sn57Bi1Ag Solder Alloy Joints

Sn57Bi1Ag alloy system meets the basic solderability requirements while reliability of solder is less known. The presence of intermetallics that form at the solder-joint interface and in the bulk solder is the primary reason to cause joint failure on simple loading. Furthermore, dissolution of soldered surface (copper, gold, silver, nickel, etc.) into the solder during reflow alters the composition of the interface leading to the formation of intermetallic phases. The present paper addresses the characterization of low temperature Sn57Bi1Ag solder alloy, its joint interface metallurgy and integrity. Generally, formation of intermetallic phases (Cu3Sn, Cu6Sn5, Ag3Sn, AuSn2, Ni3Sn4, etc.) at the solder-pad interface is in the range of 0.3 to 1.0µm. On thermal ageing at 75°C (0.55Tm), the intermetallic phases grow further up to 2.3µm, particularly CuSn and AuSn phases. In addition, to distributed eutectic tin (Sn) and bismuth (Bi) phases, fine eutectic tin and bismuth phases and primary tin (β-Sn) are also observed. Coarsening of Bi and Sn phases is noticed on thermal ageing (75°C and 100°C). The rate of coarsening increases with the supply of thermal energy promoting Sn/Bi atomic diffusion and movement of eutectic boundaries (grain boundaries). However, the Sn-Bi interface is stable without any significant changes in eutectic structures and its morphologies. The mechanical drop test of the Sn57Bi1Ag solder joint passed 120 drops, characteristic life corresponds to the number of drops for a failure of 63.2%. Evaluated as per JESD22-B111 specification to a maximum peak acceleration of 1500G and half-sine shock pulse duration of 0.5 milliseconds, soldered the alloy to copper OSP surface. The solder joint also passed 1200cycles evaluated at -40 to +125°C. Electrical connectivity of the solder joints soldered to ENIG plated test boards is recorded continuously. Crystallographic orientation of Sn and Bi second phases is observed using electron back scattered diffraction (EBSD) of thermal aged solder joints and are also presented in this paper.

A Comprehensive Review of Physical Therapy Interventions for Stroke Rehabilitation: Impairment-Based Approaches and Functional Goals.

Stroke is the fourth leading cause of mortality and is estimated to be one of the major reasons for long-lasting disability worldwide. There are limited studies that describe the application of physical therapy interventions to prevent disabilities in stroke survivors and promote recovery after a stroke. In this review, we have described a wide range of interventions based on impairments, activity limitations, and goals in recovery during different stages of a stroke. This article mainly focuses on stroke rehabilitation tactics, including those for sensory function impairments, motor learning programs, hemianopia and unilateral neglect, flexibility and joint integrity, strength training, hypertonicity, postural control, and gait training. We conclude that, aside from medicine, stroke rehabilitation must address specific functional limitations to allow for group activities and superior use of a hemiparetic extremity. Medical doctors are often surprised by the variety of physiotherapeutic techniques available; they are unfamiliar with the approaches of researchers such as Bobath, Coulter, and Brunnstrom, among others, as well as the scientific reasoning behind these techniques.

A Drop-In High-Temperature Pb-Free Solder Paste That Outperforms High-Pb Pastes in Power Discrete Applications

Sn-based high-temperature Pb-free (HTLF) solder pastes have been developed as a drop-in solution to replace high- Pb solder pastes in power discrete applications. The pastes were designed with Indium Corporation’s DurafuseVR technology, to combine the merits of two constituent powders. A SnSb-based Ag/ Cu-containing high-temperature powder, with a melting temperature above 320 degrees C, was designed to maintain high-temperature performance. A Sn-rich SnAgCu-Sb powder, with a melting temperature around 228 degrees C, was added to the paste to enhance wetting and improve joint ductility. In the design, the final joint will have the low-melting phase (the melting temperature >228 degrees C) in a controllable quantity embedded into the high-melting SnSb matrix. HTLF-1, one of the designs, maintained the bond shear strength up to 15 MPa, even around 290 degrees C. Another design, HTLF-2, has a similar bond shear strength as Pb92.5/Sn5/Ag2.5 around 290 degrees C, but exceeds substantially below 250 degrees C. The power discrete components had been built with both HTLF solder pastes for both die-attach and clip-bond through the traditional high-Pb process, which demonstrated the drop-in processing compatibility. The components survived three additional surface mounting (SMT) reflows (peak temperature upto 260 degrees C) and passed moisture sensitivity level 1 (MSL1). This confirmed that the maintained joint strength (comparable to or stronger than high-Pb), helped to keep the joint integrity within the encapsulated components in the following SMT process, even with the controlled quantity of the melting phases above 228 degrees C. Both HTLF solder pastes outperformed Pb92.5/Sn5/Ag2.5 in the resistance from drain to source when power is on (RDS(on)), even after 1,000 cycles of temperature cycling test (TCT) under 255/175 degrees C, which is attributed to the intrinsic lower electrical resistivity of Sn in both HTLF pastes. Microstructural observation had shown no corner cracks for both die-attach and clip-bond joints after TCT.

An establishing method for worn tubing joint model and the influence of wear on stress distribution of joint sealing surface

Wear has serious influence on the strength and tightness of tubing joint. In this paper, a new joint wear establishment method, “numerical cutting method,” was proposed and the stress distribution characteristics of sealing surface were analyzed. The three-dimensional modeling of a worn tubing joint under complex loads was successfully established and the finite element method was used to calculate the stress distribution on sealing surface. The influence of internal wear on the stress distribution of the sealing surface was analyzed and the failure mechanism of a worn tubing joint was revealed. The results showed that the contact stress of the worn part of the sealing surface decreases with increased wear depth of internal wear. When the internal wear depth reaches 3.0 mm, the maximum contact stress in the worn area decreases by 35.5% than that of the unworn joint along the axial direction and by 27.3% along the circumferential direction of sealing surface. While when the external wear reaches 3.0 mm, the stress distribution of the sealing surface is similar to that of the unworn joint. These mean that more attention should be paid to the prevention of internal wear during operation because an internal wear has more effect on the stress characteristics of the sealing surface than external wear. The sealing belt is located in the middle of the sealing surface, and the width of the sealing belt at different wear depths is roughly the same for two wear forms. This is beneficial to ensure the seal integrity of tubing joint.

Damage Monitoring of Composite Adhesive Joint Integrity Using Conductivity and Fiber Bragg Grating

Adhesive joints possess a number of advantages over traditional joining methods and are widely used in composite structures. Conventional non-destructive examination techniques do not readily reveal joint degradation before the formation of explicit defects. Embedded fiber Bragg grating (FBG) sensors and the resistance of carbon nanotube (CNT)-doped conductive joints have been proposed to monitor the structural integrity of adhesive joints. Both techniques will be employed and compared in the current work to monitor damage development in adhesive joints under tensile and cyclic fatigue loading. Most of the previous works took measurements under an applied load, which by itself will affect the monitoring signals without the presence of any damage. Moreover, most FBG works primarily relied on the peak shifting phenomenon for sensing. Degradation of adhesive and inter-facial defects will lead to non-uniform strain that may chirp the FBG spectrum, causing complications in the peak shifting measurement. In view of the above shortfalls, measurements are made at some low and fixed loads to preclude any unwanted effect due to the applied load. The whole FBG spectrum, instead of a single peak, will be used, and a quantitative parameter to describe spectrum changes is proposed for monitoring purposes. The extent of damage is revealed by a fluorescent penetrant and correlated with the monitoring signals. With these refined techniques, we hope to shed some light on the relative merits and limitations of the two techniques.

Review on recent advances in structural health monitoring paradigm for looseness detection in bolted assemblies

The integrity of bolted joints is still a challenging problem owing to the gross or localized slip at the interfacial surfaces of the joints when subjected to external disturbances such as vibrations. This slip escalates the interfacial movement and, thus, leads to a decrease in preload levels, that is, looseness of the bolted assemblies. In the last decade, modal analysis, wave propagation, and percussion methods were traditionally used to detect looseness in bolted connections. With an increase in computational power, machine learning algorithms such as neural networks, random forests, decision trees, and support vector machines complemented the traditional methods in accurate looseness estimation. Subsequently, this integration paved the path for real-time health monitoring of bolted joints. This paper summarizes recent investigations on looseness detection in bolted assemblies based on traditional methods and machine learning algorithms. The working principle, advantages, challenges, and applications of the aforementioned methods are also detailed in this paper. Apart from these investigations, the latest studies on the Internet of Things-based health monitoring of structures are also reviewed to explore their adaptability in remote monitoring of bolted connections for damage detection in the future.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Rotary Friction Welded AA7075 and AA5083 Dissimilar Joint

The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and microstructures, as well as the changes in hardness and tensile properties resulting from friction welding. The joint integrity was studied through various characterization techniques, and no cracks or incomplete bonding was observed. The study found that the dissimilar joints of the AA7075 and AA5083 alloys displayed higher flash formation on the AA7075 side, which has a lower melting temperature compared to the AA5083 alloy. Various zones were identified in the weld region, including the dynamic recrystallized zone (DRZ), the thermomechanically affected zone (TMAZ) consisting of TMAZ-1 (elongated grains) and TMAZ-2 (compressed/distorted grains), the heat-affected zone (HAZ), and the base metal (BM) zone. The rotary friction welded sample AA5083/AA7075-PWHT joint exhibited the highest strength (yield strength (YS): 195 ± 3 MPa, ultimate tensile strength (UTS): 387 ± 2 MPa) among all the other welded conditions, and this may be attributed to the major strengthening precipitates MgZn2 (of AA7075) formed during postweld aging. All dissimilar welds failed in the HAZ region of the AA5083 side due to the formation of coarse grains, indicating the weakest region.

ANALYSIS OF BENDING MECHANICAL PERFORMANCE OF WELDING JOINTS WITH THE ADDITION OF DIAMOND AND CIRCULAR PLATES

The design and analysis of welded joints are very useful for the safety of steel-based structures. The effect of welded joints meeting at one point on the resulting stress is a critical factor in constructing steel joints. The main objective of this research is to analyze the mechanical performance and microstructure of the welding process on diamond and circular plate joints. The analysis was carried out through experiments and finite element simulations to find out how much influence the addition of a diamond plate and circular plate had on the plate connection. The method used is to analyze the strength, hardness, and micro and macrostructure testing to determine the strength and structural changes of the metal after welding. The results of the test are then used to create an inhomogeneous model of weld joint, then the model is applied to the FEA software to be analyzed by the bending test simulation. The experimentally bending testing was carried out to examine bending performance of the test objects. From the simulation and experimental results, it is found that the shape of a circular plate measuring a diameter of 60 mm with a thickness of 6 mm is appropriate for a flat plate joint, and the flat-diamond plate measuring 60x60 mm with a thickness of 6 mm is proper for application to un-flat (cornered) plate joints. The structural integrity of a flat plate joint with a circular plate is greater than that of a diamond plate.

The humanistic and economic burden of problem joints for children and adults with moderate or severe haemophilia A: Analysis of the CHESS population studies.

Adequate prophylactic treatment and physical activity improve joint health and clinical outcomes for people with haemophilia A (HA). However, non-clinical joint-related burden of moderate (MHA) and severe (SHA) HA has not been well characterised. To quantify the joint health-related humanistic and economic burden of MHA and SHA in Europe. A retrospective analysis of the cross-sectional CHESS population studies using a patient-centric measure of joint health (problem joints, PJs: chronic joint pain and/or limited range of movement due to compromised joint integrity with or without persistent bleeding) was conducted. Descriptive statistics summarised health-related quality of life (HRQoL), work productivity/activity impairment and costs by number of PJs (0, 1 or ≥2) and HA severity. A total of 1171 patients were included from CHESS-II (n = 468) and CHESS-PAEDs (n = 703). In both studies, 41 and 59% of patients had MHA and SHA, respectively. Prevalence of ≥2 PJs was similar with MHA and SHA (CHESS-II: 23 and 26%; CHESS-PAEDs: 4 and 3%, respectively). HRQoL was worse with an increasing number of PJs (CHESS-II: .81 vs. .66 with 0 and ≥2 PJs, respectively, for MHA; .79 vs. .51 for SHA; CHESS-PAEDs: .64 vs. .26 and .72 vs. .14). Total costs increased with increasing PJs regardless of severity in CHESS-II (€2923 vs. €22,536 with 0 and ≥2 PJs, respectively, for MHA; €11,022 vs. €27,098 for SHA) and CHESS-PAEDs (€6222 vs. €11,043 for MHA; €4457 vs. €14,039 for SHA). Presence of PJs was associated with a substantial humanistic and economic burden on patients with MHA or SHA across the lifespan.

Impact of steroid injections on hip joint integrity

1University of Chicago NorthShore Family Medicine Residency Program, Chicago, IL 2University of Chicago Hospitals and Health System: The University of Chicago Medicine, Chicago, IL The corresponding author is Priya Veda Nagarajan; [email protected] The authors have no conflicts of interest to declare.

Assessment of the Structural Integrity of a Laser Weld Joint of Inconel 718 and ASS 304L

For high-temperature industries operating at nearly 750 °C (advanced ultra-super critical boilers), dissimilar welding between Inconel alloys and austenitic stainless steel (ASS) are commonly adopted. The high-temperature resistive properties of Inconel and ASS alloys are highly qualified for high-temperature applications. In this experimental study, dissimilar autogenous laser beam welding (LBW) between Inconel 718 and ASS 304L is investigated. This paper explains the detailed study on the microstructural and mechanical behavior of the LBW dissimilar joint. The microstructural study indicates the presence of laves phases in the weld zone. Additionally, the weld zone shows heterogeneous microstructural formation, owing to the non-uniform welding heat in the different areas of the weld zone. The optical images show the presence of mixed dendrites, i.e., equiaxed, cellular, and columnar morphology, in the weld zone and in the fusion zones of either side. The energy-dispersive spectroscopy (EDS) results show the presence of segregated elements (Nb, Mo, Cr, and Ti) at the weld center. These segregated elements are the reason for the occurrence of the laves phases in the weld zone. The presence of Nb and Mo may form the laves phase (Fe, Ni, Cr)2 (Nb, Mo, Ti) along with Fe, Ni and Cr. The presence of an unmixed zone is observed in the HAZ of the Inconel 718, whereas the HAZ of the ASS 304L shows the presence of an unmixed zone (UZ) and a partially mixed zone (PMZ), as observed on the optical and SEM images. To obtain the mechanical properties of the laser weld, the tensile test, microhardness test, and impact test were measured at room temperature. The tensile specimens show a brittle failure at the ASS 304L side, which was initiated from the weld top, with average tensile stress of 658.225 MPa. The reason for the ASS 304L fracture is because of the presence of UZ and PMZ, and the lower hardness value of the ASS side. The UZ and PMZ lead to the fracture of the tensile specimen along the ASS 304L side’s HAZ. The measurement of microhardness carried out along the transverse length indicates an average microhardness of 214.4 HV, and the value is 202.9 HV along the weld depth. The mixed morphology of the microstructure promotes the variation in hardness in both directions. The hardness along the length shows a high hardness value in the weld zone and uniformly decreases along the base materials. The Charpy impact test of the weld zone shows the brittle fracture of the impact specimens. From the microstructural and mechanical results, the LBW dissimilar weld between Inconel 718 and ASS 304L is qualified for safe use in high-temperature end applications, such as AUSC power plants.

Production of 192Ir sealed sources in Es Salam research reactor for non-destructive testing

Abstract An iridium-192 miniature sealed source was produced by irradiation of 12 metal disks of natural iridium (470.5 mg) under a thermal neutron flux of 9.4 × 1013 n cm−2 s−1 during 200 h in Es Salam research reactor (Algeria). The preliminary activity was measured after 10 days decay time by a CAPINTEC type CRC-712 M dose calibrator, the given activity was 1.9 × 1011 Bq (5.2 Ci). To estimate source activity, a modeling of reactor core and irradiation container with the targets was made by MCNP5 code with and without iridium targets to evaluate the effect of the disturbance and reaction; the calculated activity using disturbed flux was comparable with that measured. A non-destructive test using 192Ir sealed sources with GammaMat TSI type B(U) projectors was carried out to evaluate the integrity of the weld joint at the bend of a carbon steel pipe. The weld quality of two plates; carbon steel and stainless steel was also evaluated. In terms of sensitivity, the resulting gamma images matched well and reported a real finding on the state of tested samples.

Grey-based taguchi method for multi-weld quality optimization of gas metal arc dissimilar joining of mild steel and 316 stainless steel

Welding processes play a significant role in many fabrication and manufacturing industries. Among various welding processes that have been developed over the years, Gas Metal Arc Welding (GMAW) or Metal Inert Gas Welding (MIG) has received a lot of interest due to its ability to weld a variety of metallic materials, easy adaptation for automation, high deposition rate, high efficiency, and low capital requirement. This study focus on the optimization of the multi-performance characteristics of MIG welded butt joint of AISI 1008 mild steel and AISI 316 austenitic stainless steel by hybrid Grey based Taguchi method. L9 Taguchi orthogonal array was adopted for the optimization of the MIG welding current, voltage and gas flow rate. The weld joint integrity has been assessed in terms of the tensile strength, yield strength, percentage elongation and Vickers microhardness of the fusion zone. Welding current of 180 A, voltage of 14 V, and gas flow rate of 19 l/min were obtained as the optimal parameter setting for the MIG welding process. The tensile strength, yield strength, percentage elongation and hardness of 559.25 MPa, 382.22 MPa, 33.34%, and 250.63 HV respectively were obtained at the optimal setting. Voltage was the most significant process parameter with 63.76% contribution for the multi-performance of the weldments. The confirmatory test was performed to validate the optimization process which proved Grey based Taguchi method to be an easy but yet effective method for multi-performance characteristics optimization of welded joints.

The impact of rheumatic diseases in Iraq on pregnant women whose ages range from (25-35 years)

Rheumatoid arthritis (RA) is a chronic, recurrent inflammatory autoimmune condition characterized by persistent inflammation of the synovial joints, which over time and especially without intensive treatment, leads to erosive development, with the destruction of the articular cartilage and complete loss of joint integrity

Influence of flange geometric configuration and bolt stress on joint integrity during assembly using FEA

The aim of this study is to develop a procedure suitable to determine the maximum bolt pre-stress required for the proper gasket seating in bolted flange connections. The proposed method is valid for all the flange types and assumes that the gasket leakage must be limited so as to not affect the flange joint integrity. A 3D finite element model is used in which elastic–plastic behaviour of the flange material, non-linear gasket material behaviour and non-linear flange–gasket contact are assumed. The final goal of the developed work is to update, using a more realistic perspective, the recommendations given by ASME PCC-1 Appendix-O for bolt pre-stress values when applied to standard dimensional ASME flanges. Additionally, in this work, the effect of the straight portion length of the flange hub at its welded connection with the connected pipe and the fillet radius at the hub-flange transition on the stresses and strains distribution are also addressed.

Epigenetics as a Therapeutic Target in Osteoarthritis.

Osteoarthritis (OA) is a heterogenous, complex disease affecting the integrity of diarthrodial joints that, despite its high prevalence worldwide, lacks effective treatment. In recent years it has been discovered that epigenetics may play an important role in OA. Our objective is to review the current knowledge of the three classical epigenetic mechanisms-DNA methylation, histone post-translational modifications (PTMs), and non-coding RNA (ncRNA) modifications, including microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs)-in relation to the pathogenesis of OA and focusing on articular cartilage. The search for updated literature was carried out in the PubMed database. Evidence shows that dysregulation of numerous essential cartilage molecules is caused by aberrant epigenetic regulatory mechanisms, and it contributes to the development and progression of OA. This offers the opportunity to consider new candidates as therapeutic targets with the potential to attenuate OA or to be used as novel biomarkers of the disease.

Recent advances in nano-targeting drug delivery systems for rheumatoid arthritis treatment

Rheumatoid arthritis is a systemic inflammatory disease that can lead to articular cartilage destruction and periarticular bone erosion, thus ultimately compromising joint integrity and function. Anti-inflammatory drugs and biological agents are commonly used to treat rheumatoid arthritis, but they cannot selectively target inflamed joints, because of their systemic mechanisms, short half-lives and low bioavailability. Consequently, these agents must be used at high doses and delivered frequently, thereby increasing costs and the risk of adverse effects. Drug delivery systems, such as nanoparticles, liposomes and micelles, can significantly prolong drug half-life in the body and enable targeted delivery into the joints. In this review, we comprehensively describe the pathogenesis and clinical diagnosis of rheumatoid arthritis, and summarize recent advances in targeted therapeutic strategies, particularly nano-targeting systems for rheumatoid arthritis.

Effects of steps on the load bearing capacity of 3D-printed single lap joints

Damage in adhesively bonded joints typically initiates in the overlap area due to high level of bonding (peel) stress. Different approaches are being considered to decrease the peel stress and improve the overall strength of the joint. One possible approach is to shape the over lap area into a stepped form configuration and enhance the performance of the joint. In the current study, we investigate effects of stepped-shape overlap area on the load bearing capacity of additively manufactured single-lap joints. To this aim, stepped-lap adhesively bonded joints with different designs and geometries in the overlap (bonding) area are considered with 3D-printed polylactic acid (PLA) adherends using the fused deposition modeling (FDM) process. Three configurations with different step sizes are considered to manufactured a set of adhesively bonded single-lap joints and to investigate the optimum length of the steps. The results are compared with our previous experimental findings on 3D-printed conventional single-lap joints. The obtained outcomes reveal that creating steps in the overlap area has a significant influence on the structural integrity and fracture load of 3D-printed adhesive-bonded joints and the bonded structures with identical step size in boding area reveal a better performance in load carrying capacity and shows a higher fracture load. Parallel to the experimental practices, a finite element model also developed to simulate the load carrying performance of the adhesively bonded single-lap joints with equal step size and 3D-printed PLA adherends. The FE model confirms the experimental outcomes and reveals the details of the cohesive failure and damage evolution mechanism in this bonded structures with PLA printed adherends. The proposed technique has a great potential to be a competitive alternative to conventional single-lap joints made by 3D printing. The presented results can be used for further fabrication of 3D-printed joints with a better structural performance.

Structural health monitoring of Cerasol® roof tiles with embedded FBG sensors

ABSTRACT There are currently little widely used structural health monitoring (SHM) techniques for structural adhesive joints. In this study, integrated fibre Bragg grating (FBG) sensors are used to examine the structural integrity and reliability of functional adhesive joints. There is an even greater demand for structural monitoring during operation or quality control of adhesive joints during production as more industries embrace high performance structural adhesives in fail-safe designs. Smartroof® photovoltaic (PV) roof tiles are used in this study to validate a real-time health monitoring of the adhesive connection between the PV glass plate and the polymer frame. A structural epoxy and a modified siloxane (MS) polymer are assessed. To assure measurement accuracy and to provide a better understanding of the strain sensing mechanism, the data is qualitatively compared with a finite element model. It is demonstrated that using embedded FBG sensors is accurate and adequate for in situ real-time structural health monitoring. Nevertheless, it remains difficult to ensure and manage the fibre’s position in the adhesive layer.