Iron-based Shape Memory Alloys Research Articles

Experimental-analytical investigation of accelerated bridge construction concrete columns with self-centering Fe-SMA bars subjected to near-fault ground motions

Excessive seismic damage and residual deformation in bridge piers can result in time-consuming post-earthquake repair and replacement, which will adversely affect the recovery and seismic resilience of the transportation infrastructure. Seismic damage or permanent deformation in bridges can be minimized using advanced materials and novel technologies, of which shape memory alloy (SMA) has gained substantial momentum. The goal of this study is to investigate the feasibility of using unbonded iron-based shape memory alloy (Fe-SMA) bars as self-centering elements in accelerated bridge construction (ABC) piers to reduce residual seismic deformation. Shake table testing is performed on a one-third-scale bridge column specimen subjected to near-fault ground motions. A numerical model of the test specimen is developed in OpenSees, and the “pre-test” analysis results are compared with the experimental measurements. Acceptable correlations are observed between the simulated and measured residual drifts, accelerations, forces, and hysteretic responses. Furthermore, the test results are compared to that of a similar conventional cast-in-place RC column without self-centering elements. The maximum residual drift ratio in the tested Fe-SMA column specimen is found to be much smaller than the conventional column specimen highlighting the potential benefits of the proposed design.

Influence of activation temperature and prestress on behavior of Fe-SMA bonded joints

The prestressed strengthening of structures via use of bonded iron-based shape memory alloys (Fe-SMAs) has proven promising, albeit with concerns regarding the temperature dependency of the adhesive properties. In this study, the effect of activation temperature and generated prestress are investigated experimentally. Six Fe-SMA-to-steel adhesively bonded joints, comprising different Fe-SMA strips (non-prestrained and prestrained) and activation strategies (full activation and partial activation), were prepared, activated via electrical resistance heating, and tested under quasi-static loading. It is found that the bond–slip behavior of a joint with activation can be modeled by that of an equivalent non-activated joint. The generated prestress influences the full-range behavior by raising the base tensile stress level of the Fe-SMA strip, with negligible effects on further aspects of the full-range behavior. With the increasing activation temperature, the fracture energy is initially increased and eventually reduced, while the bond capacity and effective bond length are retained almost constant.

Bond behavior between Fe-SMA strips and mortar in masonry joint after resistive heating

In recent years, iron-based shape memory alloys (Fe-SMA) have attracted much interest as an innovative prestressing material with the ability to eliminate the need for on-site tensioning and complex anchoring. This unique property offers application potential for using Fe-SMA to effectively strengthen masonry structures, especially in narrow space joint strengthening applications. Here, based on the premise that the Fe-SMA needs heating to generate prestress, the bond characteristics between the Fe-SMA strips and mortar in the masonry joint after resistive heating were investigated. The effects of various factors, such as heating time, strips surface condition, and bond length, on the bond behaviors were analyzed. The results show that under reasonable resistance heating conditions, Fe-SMA did not significantly damage the bonding interface during masonry joint strengthening. After resistive heating at a heating temperature of 200 °C and a heating time of 30 s, the bond strength of the specimens remained high, and it only decreased by 9.38 %∼10.36 % of the bond strength of the unheated specimen. Following the rough surface treatment of Fe-SMA strips, the bonding properties of the Fe-SMA strips were obviously improved before and after resistive heating, and bond energy dissipation was the clearest performance increase to over 5 times the original value. In addition, a prediction model for the bond strength between the Fe-SMA strip and mortar in masonry joint strengthening after resistive heating was proposed and could provide references for subsequent studies.

Experimental study on the active continuity of HCS structural floors using Iron-based Shape-Memory Alloy rebars

Despite the relatively recent introduction of Iron-based Shape-Memory Alloys (Fe-SMA) into structural engineering, more than 150 real applications have been performed to date in Central Europe, especially in retrofitting projects. Thanks to the Shape-Memory Effect, a prestrained and correctly anchored Fe-SMA bar can generate recovery stresses when heated up to 160 °C (activation) or more, and then cooled down. This paper presents research results about using Fe-SMA reinforcing bars as active (prestressed) continuity reinforcement in the hogging bending moment region of Hollow Core Slabs structural floors (HCS-sf). An experimental campaign was designed and carried out on eight HCS-sf specimens, four with concrete topping and four without, and two different slab heights. Using the HCS-sf specimens with the activated Fe-SMA bars resulted in better behaviour in the Service Limit State, which preliminarily proved the effectiveness of the proposed methodology for the specimens with concrete topping, although construction problems arose with the specimens without concrete topping.

Hybrid strengthening and flexural behaviour of post-tensioned laminated glass beams

The strengthening of glass for structural applications is challenging. EBR (External Bonded Reinforcement) reinforcement is often preferred, although limitations result from stress concentrations especially in the case of post-tensioning. This study explores the use of CFRP (Carbon Fiber Reinforced Polymers) and/or Fe-SMA (Iron-based Shape Memory Alloys) as reinforcement in hybrid and alternative configurations. Five full size laminated glass beams were tested in flexure, combining NSM (Near-Surface Mounted) and EBR techniques and exploring the efficiency of different alternative strengthening layouts (i.e. reinforcement material versus application technique) to overcome the current shortfalls of glass strengthening for structural applications. Even for lower reinforcement ratios, hybrid strengthening systems performed better and increased load-carrying capacity while delaying crack-induced deboning failure, when compared to conventional EBR systems. Residual strength ratio increased from 87 % to 160.8 % and ductility from 407 % to 971 %. The hybrid system combining NSM-CFRP and EBR-SMA reinforcements showed the best performance, increasing the initial fracture stress of glass and maintaining sufficient residual strength capacity, while allowing the safe post-tensioning.

Experimental study on mechanical properties of bolted joints between Fe-SMA and steel plates

The new intelligent material Iron-based Shape Memory Alloy (Fe-SMA) brings novel solutions for the performance rehabilitation of existing steel structures. To fully utilize the potential of the Fe-SMA active prestressed reinforcement, the systematic study of reliable joint is significant. Therefore, the bolted joints between Fe-SMA and steel plates was experimentally studied in this paper, whose reliability and convenience in metal structures have been generally accepted. Firstly, a series of 15 mechanical performance tests of bolted joints between Fe-SMA and steel plates were carried out. The key influencing parameters of the bolted joints were obtained, and different failure modes were observed, which can provide experimental verification for further finite element modelling and theoretical study. Furthermore, the effects of end distance e, edge distance s, bolt diameter d, thickness of Fe-SMA plate t and bolt layout on the ultimate load-bearing capacity, initial stiffness and failure modes of the bolted joints between Fe-SMA and steel plates were discussed, and some specified design suggestions on bolted joints between Fe-SMA and steel plates were proposed. This paper mainly aims to provide the experimental basis and design recommendations for compilation of the relevant specifications, which is expected to advance the scientific application of Fe-SMA in the performance rehabilitation of steel structures.

Self-centering technique for existing concrete bridge columns using prestressed iron-based shape memory alloy reinforcement

Reinforced concrete (RC) bridge columns are expected to undergo large inelastic displacements during major earthquake events, which in turn can result in residual displacements that can potentially affect the functionality of the bridge. While post-tensioning has been used to develop self-centering column systems for new bridge construction, the self-centering of existing bridge columns remains a challenge, mainly due to the limitations associated with the application of conventional post-tensioning techniques to existing structures. This study aims to address this important research gap by developing a robust self-centering technique to mitigate the residual displacements of the existing bridge columns. The proposed self-centering technique exploits the unique self-prestressing characteristics of iron-based shape memory alloy (Fe-SMA) bars to prestress existing bridge columns. The effectiveness of the proposed technique was evaluated through the large-scale experimental investigation of four columns. The variables of the study included the ratio of steel to Fe-SMA reinforcement, the total longitudinal reinforcement, and the initial prestress. The experimental results showed that the proposed technique could significantly reduce the residual drifts of existing bridge columns. The residual drift of the columns was found to be less than 1% up to a target drift of 4% when the ratio of steel to Fe-SMA reinforcement was ≤ 0.3. The paper concludes with a discussion of the self-centering mechanism of columns reinforced with prestressed Fe-SMA bars, where it is shown that, unlike post-tensioning tendons which do not contribute much to the energy dissipation of columns, prestressed Fe-SMA bars begin to contribute to the energy dissipation after the initial prestressing is lost at high drifts, resulting in an enhanced seismic resilience of the columns.

Experimental study on anchorage and activation performance of Fe-SMA strips for structural reinforcements

Iron-based shape memory alloy (Fe-SMA), taking advantage of its unique shape memory effect, is increasingly used to strengthen and rehabilitate deficient or deteriorated structures. The connection and activation methods are considered as the key techniques for the application of Fe-SMA. In this work, the China-made Fe-SMA strips were used and the material characteristics at room and elevated temperatures were examined. Two types of mechanical anchorages were designed to connect Fe-SMA strips with steel beam. A simple setup was designed to evaluate the performance of anchorages. Fe-SMA strips were heated by a low-cost activation method with hot gun. The temperature transfer law and recovery stress of Fe-SMA strips during activation were monitored during experiment. The test results indicated the mechanical anchorages showed good performance and the strength of Fe-SMA strips at failure was over 85% of its ultimate strength. The influence of activation decreases rapidly with the increase of distance from heating area, and the elevated temperature did not cause thermal damage on the reinforced structure. A theoretical equation was proposed based on the temperature transfer law to predict temperature of each point on Fe-SMA strips, which could be employed in determining the bonding length of adhesive bonding joint for Fe-SMA reinforcement in practice.

Experimental and numerical study on cracked steel bridge diaphragm reinforced with bonding Fe-SMA plate

This study proposes a novel iron-based shape memory alloy (Fe-SMA) plate covered crack-stop hole method for repairing fatigue cracks at the arc-shaped cutout of the transverse diaphragm on the orthotropic steel bridge deck (OSD), which aims to reduce stress levels and increase the stiffness of the cracking part, in order to alleviate the stress concentration problem at the edge of the crack-stop hole. Firstly, a static tensile loading test on specimens strengthened by the proposed method was conducted. Results revealed that the edge stress of the crack-stop hole repaired by Fe-SMA plates with thicknesses of 1.75 mm activated at 150 °C, 2 mm activated at 200 °C, 2 mm activated at 150 °C, and 1.75 mm unactivated was reduced by 83.93%, 88.45%, 81.84%, and 66.76%, respectively, compared with those repaired only by the crack-stop hole method. Then, numerical simulations were carried out to analyze the geometric parameters and activation temperatures of the Fe-SMA plate, with the prestress of Fe-SMA simulated by an equivalent temperature method that had been validated through an activation test. Results showed that with the thickness of the Fe-SMA plate increasing from 1 mm to 3 mm, the stress concentration factor K of the hole edge decreased from 2.5 to 0.5. In practical application, it is recommended to use 2 mm-thick Fe-SMA plates, with a width just exceeding the crack-stop hole by approximately 10 mm to completely cover the cracking part and the hole. Further analysis indicates that the recommended activation length is 50–100 mm. Moreover, the repair effect is positively correlated with the activation temperature of Fe-SMA plates, indicating that higher activation temperatures can be used to improve repair efficiency within the acceptable temperature range.

Compression behavior of concrete columns combinedly confined by FRP externally wrapped Fe-SMA strips

Compared to the traditional passive confinement to strengthen concrete columns, previous studies testified that the active confinement provided by prestressed materials not only can improve certainly the material utilization rate, but also alleviate the hysteresis of confinement stress. Meanwhile, the iron-based shape memory alloy (Fe-SMA), that performs the shape memory effect, can be utilized as an innovative strengthening method to rapidly apply the active confinement on concrete columns. In this paper, an innovative active strengthening method by using Fe-SMA strips was proposed, which can provide the potential to make emergency repairing for the damaged columns after the earthquake or impact. The compressive behavior of concrete columns separately confined by the passive confinement, the active confinement, and the hybrid confinement was researched by the compression test, and the different net-spacing strips and different layers of FRP strips were considered as well. The compression test was used to explore the compressive behavior of concrete columns that were confined by three different methods: passive confinement, active confinement, and hybrid confinement, and the test also considered different spacing distance strips and different FRP layers. According to the results, these three confinement types can effectively enhance the load carrying capacity and corresponding deformation of stub columns, especially the hybrid confinement. Finally, a verifying calculation was proposed to predict the peak compressive stress of these specimens, serving as a reference for selecting appropriate methods to strengthen concrete columns.

Feasibility of iron-based shape memory alloy strips for shear strengthening of damaged RC beams promoting the formation of plastic hinges

This research focuses on the proof of concept of the feasibility of iron-based shape memory alloys strips (Fe-SMA) to strengthen damaged structures by promoting the yielding of longitudinal reinforcement. For this purpose, an experimental campaign on real-scale reinforced concrete beams previously damaged on shear and retested after being strengthened was carried out. The strengthening technique consists of external Fe-SMA strips wrapping the beams. The results show a very significant increase in both shear strength and ductility. In addition, shear predictions were calculated and compared by several design models. This study highlights the potentialities of Fe-SMA as a strengthening technique for damaged beams on shear.

4D printing of recoverable buckling-induced architected iron-based shape memory alloys

Architected materials exhibit extraordinary properties in comparison with conventional materials and structures, resulting in additional functionality and efficiency by engineering the geometry in harmony with the base material. Buckling-induced architected materials (BIAMs) are a class of architected materials that exhibit a significant potential to absorb and dissipate energy owing to their local instabilities. Previous studies have shown a trade-off between energy dissipation and geometrical recoverability in metallic BIAM, which limits their use in applications that require both of these features. This study, for the first time, presents 4D printing of buckling-induced architected iron-based shape memory alloys (BIA Fe-SMAs) using laser powder bed fusion (LPBF). The results show that 4D printing of BIA Fe-SMAs can offer both energy dissipation and geometrical recoverability (i.e., recentring). The study was conducted on two different alloy compositions of Fe-17Mn-5Si-10Cr-4Ni. Quasi-static cyclic tests were performed on the two BIA Fe-SMAs, and the samples were subsequently heated to 200 °C to activate the shape memory effect (SME) of the base material. The samples could recover the residual deformations accumulated during the cyclic load owing to the SME of the base material, which led to shape-recovery ratios of 96.8 and 98.7% for the studied BIA Fe-SMAs. The results of this study demonstrate that 4D printing of BIA Fe-SMAs can yield an enhanced multi-functional behavior by combining the material's inherent functional behavior with the functionalities of the architected structure. Notably, BIA Fe-SMA samples could reconfigure their initial shape without damage after densification, which sets them apart from conventional crushable lattices.

Surface preparations and durability of iron-based shape memory alloy adhesively-bonded joints

Developing a bonded prestressed solution for strengthening structures utilizing an iron-based shape memory alloy (Fe-SMA), is of significant interest. This study is the first systematic investigation of adhesively-bonded Fe-SMA joints to achieve complete cohesive failure, which is an essential prerequisite for bond integrity. The Fe-SMA surface was prepared by combining UV/ozone exposure (UV), sol–gel (SG), and primers (PC, PNC), and the failure mode of the joint was investigated using the floating-roller peel test. Furthermore, the joint durability was studied through artificial aging using a salt spray cabinet. Cohesive failure was obtained for all investigated adhesives, and the effect of every surface preparation step was described. The application of sol–gel was found to be a crucial step in obtaining complete adhesive failure.

Strengthening of steel beams with adhesively bonded memory-steel strips

This study entails the development of a non-destructive prestressed strengthening solution for steel beams using adhesively bonded memory-steel (also known as iron-based shape memory alloy, Fe-SMA) strips. The Fe-SMA strip is activated via heating and subsequent cooling to generate prestress, while the two ends of the Fe-SMA strip are adhesively bonded as anchorages. The behavior of the Fe-SMA-to-steel bonded joints was investigated through lap-shear tests, from which an effective bond length of approximately 120 mm was determined. Subsequently, a strengthening solution for a 5.3 m span steel I-beam was designed based on finite element analysis. A 4200 mm × 100 mm × 1.5 mm Fe-SMA strip was bonded to the bottom of the steel beam with a bond length of three times the effective bond length, and a two-step activation strategy using torches was proposed. Furthermore, the designed strengthening solution was experimentally tested. With activation to the target temperature of 240 °C, the Fe-SMA developed a prestress level of approximately 280 MPa. A series of static and fatigue four-point bending tests were conducted. After 3 million cycles of fatigue loading, no debonding or degradation was observed for the adhesively bonded Fe-SMA-strengthened specimen; this demonstrated the reliable performance of the strengthening solution under service loads.

Numerical Investigation of Flexural Behavior of Reinforced Concrete (RC) T-Beams Strengthened with Pre-Stressed Iron-Based (FeMnSiCrNi) Shape Memory Alloy Bars

Shape memory alloy (SMA) is a material that can change shape in response to external stimuli such as temperature, stress, or magnetic fields. SMA types include nitinol (nickel-titanium), copper-aluminum-nickel, copper-zinc-aluminum, iron-manganese-silicon, and various nickel-titanium-X alloys, each exhibiting unique shape memory properties for different applications. Reinforced concrete (RC) T-beams strengthened and pre-stressed with Fe-SMA bars are numerically investigated for their flexural response under the influence of various parameters. The bars are embedded in a concrete layer attached to the beam’s soffit. Based on the numerical results, it was found that increasing the compression strength from 30 to 60 MPa slightly improves the beam’s strength (by 2%), but it significantly increases its ductility by approximately 45%. As opposed to this, the strength and ductility of the pre-stressed T-beam are considerably improved by using a larger diameter of Fe-SMA bars. Specifically, using 12 mm Fe-SMA bar over 6 mm resulted in 65% and 47% greater strength and ductility, respectively. Furthermore, this study examines the importance of considering the flange in the flexural design of pre-stressed beams. It is seen that considering a 500 mm flange width enhanced the ductility by 25% compared to the rectangular-section beam. The authors recommend further experimental work to validate and supplement the calculations and methodology used in the current numerical analysis.

Enhancing the Shear Capacity of RC Beams with Web Openings in Shear Zones Using Pre-Stressed Fe-SMA Bars: Numerical Study

Openings in the shear span can significantly affect the structural behavior of reinforced concrete (RC) beams, particularly in terms of shear capacity and crack propagation. This paper aims to investigate the feasibility of strengthening the web opening in the shear zone of RC beams by using iron-based shape memory alloy (Fe-SMA) bars, providing valuable insights for structural engineers and researchers. Numerical analysis with ABAQUS/CAE 2020 software was employed in the current study. The research was divided into six groups of beams with web openings of different lengths (150, 300, and 450 mm), prestressing levels (0%, 30%, and 60%), and reinforcement diameters (14, 18, and 22 mm) of Fe-SMA bars. The results show that the presence of web openings can cause a significant reduction in the cracking and ultimate loads of the beams, with reductions ranging from 11% to 50% and 36% to 48%, respectively. However, by adding pre-stressed Fe-SMA bars around small web openings (100 × 150 mm), the shear capacity of the beam is restored, and the beam exhibits behavior similar to solid beams. Additionally, activating the Fe-SMA bars by 30% and 60% resulted in almost similar cracking loads but improved load-carrying capacity of the beam with small openings by 12% and 9%, respectively, compared to the solid beam. The technique proposed for enhancing shear strength is most effective for beams with small (100 × 150 mm) and medium (100 × 300 mm) web openings as it can restore both the beam’s shear strength and stiffness. However, for beams with larger web openings (100 × 450 mm), the use of activated Fe-SMA beams can recover almost 90% of the solid beam’s shear capacity. Furthermore, reinforcing small openings with Fe-SMA bars of different diameters enhances beam shear capacity and stiffness, while for larger openings, higher Fe-SMA reinforcement ratios could potentially restore the beam’s full strength and stiffness. This study emphasizes the importance of strengthening web openings in RC beams, particularly in shear zones, and provides significant insights into how to strengthen beams with web openings, thereby contributing to developing safer structures. However, further laboratory experiments are recommended to validate, complement and extend the findings of this numerical study.

Wire and arc additive manufacturing of Fe-based shape memory alloys: Microstructure, mechanical and functional behavior

Shape memory alloys (SMA) are a class of smart materials with inherent shape memory and superelastic characteristics. Unlike other SMAs, iron-based SMAs (Fe-SMA) offer cost-effectiveness, weldability, and robust mechanical strength for the construction industry. Thus, applying these promising materials to advanced manufacturing processes is of considerable industrial and academic relevance. This study aims to present a pioneer application of a Fe–Mn–Si–Cr–Ni–V-C SMA to arc-based directed energy deposition additive manufacturing, namely wire and arc additive manufacturing (WAAM), examining the microstructure evolution and mechanical/functional response. The WAAM-fabricated Fe-SMAs presented negligible porosity and high deposition efficiency. Microstructure characterization encompassing electron microscopy and high energy synchrotron X-ray diffraction revealed that the as-deposited material is primarily composed by γ FCC phase with modest amounts of VC, ε and σ phases. Tensile and cyclic testing highlighted the Fe-SMA's excellent mechanical and functional response. Tensile testing revealed a yield strength and fracture stress of 472 and 821 MPa, respectively, with a fracture strain of 26%. After uniaxial tensile loading to fracture, the γ → ε phase transformation was clearly evidenced with post-mortem synchrotron X-ray diffraction analysis. The cyclic stability during 100 load/unloading cycles was also evaluated, showcasing the potential applicability of the fabricated material for structural applications.

Recovery stress behavior of Fe-SMA under fatigue and thermal loading

The present paper investigates mechanical properties and recovery stress behavior of an iron-based shape memory alloy (Fe-SMA) with a special focus on the effect of fatigue and thermal loading. Change in recovery stress of activated Fe-SMAs subjected to fatigue at RT, −20 °C, 60 °C, and −20 to 60 °C was monitored. A second activation after fatigue was performed to investigate the retrievability of the lost recovery stress owing to fatigue. Coefficients of thermal expansion (CTEs) of the samples with different activation histories were also calculated. Results showed that the maximum reduction in recovery stress after two million cyclic loads of Δɛ=0.070% was approximately 20% under RT and −20 °C. A high temperature (60 °C) weakened such detrimental effect owing to higher critical stresses for martensitic transformation at higher temperatures, leading to only 10% reduction in recovery stress. Loss in the recovery stress due to fatigue was pronouncedly retrieved by a reactivation regardless of the temperature scenarios. This study extends understanding of recovery stress behavior of Fe-SMAs subjected to fatigue and thermal loading, and explores the retrievability of relaxed recovery stress by a second activation.

A strength prediction of joints by Fe-Mn-Si-Cr shape memory alloy through strain monitoring during pre-processes including diameter expansion and tightening by heating

To guarantee the functionality of the pipe joint in different service environments, the evaluation of its strength is critical. Typically, the assessment is performed after completing the pipe joint assembly. However, it is pretty inconceivable to examine each pipe joint’s strength in the environment for actual installations. Therefore, a strength prediction of pipe joints is required as similar to the bolted-flange systems. Due to the unique manufacturing process of the pipe joint made of shape memory alloys (SMAs), the strength prediction before the installation becomes possible by means of its pre-processing. This work chooses the pipe joint made of the iron-based shape memory alloy (Fe-SMA), which is very promising in the joint families in SMAs because of its low weight. In the diameter expanding process of the Fe-SMA hollow cylinder with different methods, both the circumferential and axial strains are measured. After heating, the cylinder tightens round bar or pipes made of SUS304 due to the shape memory effect. A measurement of the circumferential strain during thermal tightening is also made for each diameter expansion method. After that, it is attempted to identify the axial push-out strength and bending strength of the joints by measuring strain during the diameter expansion and thermal tightening processes. The results demonstrate that both the axial push-out strength and bending strength of pipe joints can be predicted in prior to the installation through the measured strain during the diameter expansion and heating processes.

Debonding model for nonlinear Fe-SMA strips bonded with nonlinear adhesives

The application of adhesively-bonded joints for strengthening of structures using iron-based shape memory alloys (Fe-SMAs) has recently emerged in construction. Fe-SMAs and the majority of structural adhesives exhibit a pronounced nonlinear material behavior, which may result in a favorable ductile failure mechanism. The development, however, of a mechanical model to predict the structural behavior of the joint is non-trivial due to the presence of nonlinearity in the adherent and adhesive. This study aims to propose a semi-analytical and semi-numerical model for describing the mechanical behavior of Fe-SMA-to-steel adhesively bonded joints. The developed model serves three main functions: (i) estimating the bond capacity for a given interfacial fracture energy, and vice versa; (ii) processing the bond–slip (τ−s) behavior directly from the load–displacement (F−Δ) curve, and vice versa; and (iii) delivering a numerical method to simulate the full-range mechanical behavior of the bonded joints, namely the behavior at different loading stages. The model is validated using the experimental testing of 26 Fe-SMA-to-steel lap-shear joints, as well as 24 further bonded joints subject to shear with different adherents (e.g., stainless steel strips and Nickel–Titanium SMA wires) and base materials (e.g., concrete and composite polymer). An experimental data processing protocol, on the basis of the experimentally measured force–displacement (F−Δ) behavior and the distributed displacement along the bond line (s−x) via the Digital Image Correlation (DIC) technique, is further proposed to assess the full-range behavior of bonded joints.