Fiber-reinforced Thermoplastics Research Articles

In-Situ Computed Tomography — Analysis of a Single-Lap Shear Test with Composite-Metal Pin Joints

Lightweight design in the form of intelligent multi-material structures that combine the advantages of high strength steel and continuous fibre reinforced thermoplastics (CFRTs) gain increasing relevance. In this context, the joining operation is a major challenge as it has to be time and cost efficient and the resulting joint has to exhibit a high mechanical durability. One possible approach is the use of cold formed pin structures, which can be inserted into the CFRT to create a form fitting joint under avoidance of fibre damage as it is commonly the case for bolted or riveted joints. The deformation phenomena of pin joints are usually investigated by macrosectioning or (ex-situ) computed tomography. However, due to resetting elastic deformations and cracks that close after unloading an inaccurate state of the inner joint structure is measured. Furthermore, an investigation of different stages with increasing load and progressing failure is very time consuming, because multiple samples have to be tested and investigated. Alternatively, in-situ computed tomography (in-situ CT) can be used to investigate the testing of pin joints. In this paper, a method for in-situ CT analysis of a single-lap shear test with composite-metal pin joints is presented. The pins are plastically extruded to a height of approx. 1.8 mm from the metal sheet (1.5 mm thick) and are pressed into a locally heated glass fibre reinforced thermoplastic (FRT) sheet (approx. 2 mm thick) creating a form fit. Specimens with quasi-unidirectional fibre reinforcement in 0° and 90° direction are tested. With this procedure, the three-dimensional deformation of the joint can be observed and failure phenomena can be identified for each reinforcement direction respectively. Thus, this method can also be used for validating numerical simulations.

Process chain for forming and consolidating fiber-reinforced thermoplastics and metallic sheets in a two-stage isothermal tool

Due to their good mechanical properties and low structural weight, multi-material structures are a promising approach in the automotive industry to lightweight design, body construction and functionalization. Especially metal and plastic are mainly combined to achieve improved properties of the final component compared to mono-material structures. This paper describes the development of a manufacturing cell for the joint forming and heat-assisted press joining of steels and continuous fiber-reinforced thermoplastics in the form of unidirectional carbon-fiber tapes. In order to achieve shorter cycle times and to ensure economical production, a manufacturing cell, supplemented with automated handling by means of two robots and an isothermal, two forming stages tool concept was developed and tested. The composite components produced were tested with regard to their mechanical performance. The feasibility of the production was demonstrated. All composite components had a higher specific load capacity than a pure steel component. Cycle times of well under 60 seconds were achieved. An enormous reduction in process time compared to variothermal tool concepts could be achieved with the new manufacturing cell.

Incremental design process for vehicle structural components using thermoplastic-based composites: A simulation-guided approach for door anti-intrusion beams

The design of safety-related structural components in automobiles is a critical phase. Most car manufacturers are aiming at reducing vehicle weight considering continuous fiber-reinforced thermoplastics as candidate to replace metal-based structural components. However, this replacement cannot compromise the safety level already achieved by metal-based designs. A good example is the side door anti-intrusion beam, which is a passive safety component to protect the passengers under a lateral impact. This paper presents an incremental design process to achieve a functional side door anti-intrusion beam fully made of glass fiber reinforced thermoplastic conceived to replace metal-based ones. The reader is guided along the design challenges, where the mechanic-based reasons to adapt the part geometry and composite layout are explained in detail. This incremental design process uses a fully FEM-based approach allowing to reach a standard-defined absorbed energy of 1000 J in a lateral collision. From the simulation analysis, it was found that by implementing essential modifications in the beam’s cross-section corrugation, the damage progression can be slowed down leading to an increase of absorbed energy. Additionally, the enhancement of one extra ply in the proper direction solves severe fracture in the clamping area. The final composite design not only performs similarly to its metal-based counterpart, but also considers aspects of production feasibility. This trip along the design process concludes with the production of the simulate-designed component and its effectiveness under lateral impact is demonstrated. To meet the safety regulations, the model is thoroughly validated against the real impact test by analyzing the response in force, intrusion, energy and damage.

Mechanical Properties of Weld Lines in Injection-Molded Carbon Fiber-Reinforced Nylon (PA-CF) Composites.

Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber-reinforced thermoplastics are still rather few. In this study, the effects of injection temperature, injection pressure, and fiber content on the mechanical properties of weld lines were studied for carbon fiber-reinforced nylon (PA-CF) composites. The weld line coefficient was also calculated by comparing specimens with and without weld lines. The tensile and flexural properties of PA-CF composites significantly increased with the rise of fiber content for specimens without weld lines, while injection temperature and pressure demonstrated slight influences on mechanical properties. However, the existence of weld lines had negative influences on the mechanical properties of PA-CF composites due to poor fiber orientation in weld line regions. The weld line coefficient of PA-CF composites decreased as fiber content increased, indicating that the damage of weld lines to mechanical properties increased. The microstructure analysis showed that there were a large number of fibers distributed vertically to flow direction in weld lines regions, which could not play a reinforcing role. In addition, increasing injection temperature and pressure facilitated fiber orientation, which improved the mechanical properties of composites with low fiber content, while weakening composites with high fiber content instead. This article provides practical information for product design containing weld lines, which helps to optimize the forming process and formula design of PA-CF composites with weld lines.

Effect of thermal condition on isothermal-pressing joined strength of silanized Al alloy/carbon fiber-reinforced polyamide-6

Carbon fiber-reinforced thermoplastics (CFRTPs) and lightweight metals are widely used in multi-material structures owing to their high strength and excellent corrosion resistance, thus stimulating research on various heat-assisted techniques to join them. Currently, the isothermal-pressing process has been developed to realize sound interface joining between CFRTP and Al alloy under relatively uniform thermal conditions. However, a quantitative investigation of the interaction between thermal conditions, chemistry reactions, and joining strength is still lacking. This current investigation analyzed chemical reaction state and resultant bonded strength of isothermal-pressing joined interface of silanized 5052 Al alloy and carbon fiber-reinforced polyamide-6 (CF/PA6) under various thermal conditions. X-ray photoelectron spectroscopy and Raman scattering analysis showed the increasing consumption of epoxy groups on silanized 5052 Al alloy side with the increase in joining temperature and residence time. This suggested higher temperatures and sufficient high-temperature duration times could efficiently promote the interface chemical reaction, increasing interface bonding strength. As the joining temperature or residence time increased, the fracture location gradually shifted from the silane coupling layer/re-solidified resin interface to the re-solidified resin close to interface, and even it directly passed through CF/PA6 along the thickness direction. Under the current adopted conditions, a critical high-temperature duration time of ∼6.0 s at least was recommended by optimizing the joining time to achieve high-strength joining between 5052 Al alloy and CF/PA6. The findings will guide optimizing the joining conditions in heat-assisted joining processes of Al/CFRTP hybrid structures.

Experimental characterization and phenomenological modeling of nonlinear viscoelasticity, plasticity and damage of continuous carbon fiber-reinforced thermoplastics

The presented work addresses the experimental characterization and phenomenological modeling of the complex rate dependent mechanical response of continuous fiber-reinforced thermoplastics (cFRTP). The theoretical basis is given by the concept of an equilibrium curve of the material which provides a comprehensive framework for separating the mechanical response into a rate dependent overstress and a rate independent equilibrium stress. In long-term creep and relaxation tests, it is shown that relaxation tests provide several advantages over creep tests when determining the equilibrium response. A stepwise loading–unloading relaxation (SR) test is proposed which makes it possible to extract nonlinear viscoelasticity, damage and plasticity present in the material from a single test. The application to cFRTP is exemplified by using the proposed method for the experimental characterization of a continuous carbon fiber-reinforced polycarbonate (CF-PC). Based on the obtained experimental data, a phenomenological material model is developed which describes the mechanical response of a unidirectional ply. The model consists of an overstress branch addressing the nonlinear viscoelastic material response and an equilibrium branch that utilizes a coupled damage-plasticity approach. After calibrating the model using the experimental data, it is shown that the proposed model is able to accurately reproduce the mechanical response of cFRTP.

Fiber orientation in continuous fiber-reinforced thermoplastics/metal hybrid joining via multi-pin arrays

Abstract Continuous fiber-reinforced thermoplastics (CFRTs) can in combination with high-strength metals offer characteristics that cannot be achieved with mono-material parts. One possible example is the combination of locally high-temperature resistance in the metal component with superior weight-related mechanical properties due to the CFRT component. This approach requires a reliable and durable joining technology, which considers the material-specific properties and allows to exploit the full potential of CFRT/metal hybrid parts. A promising approach in the field of CFRT/metal joining is the use of metallic pins, which can be embedded in the locally heated CFRT component to create a form-fitting joint. In the current state of the art, primarily single-pins are investigated and characterized: especially the distinct fiber orientation in the direct pin pressing process is only described for single-pin joints. Behind this background, the present study aims at creating an understanding of the fiber orientation mechanism for multi-pin arrays. Therefore, in the scope of this study, unidirectional reinforced glass fiber/polypropylene samples are joined via direct pin pressing and infrared heating with different 1D and 2D multi-pins arrays with different pin-diameters, spacing and pin distributions. The resulting joint morphology is consequently analyzed using micro-computer-tomography. Based on the performed investigations, a model for the fiber displacement mechanism is proposed, and the first recommendations for the design of fiber-friendly multi-pin joints with unidirectional reinforcements are given. It showed that especially pin-spacing in fiber orientation in dependency of the pin diameter is critical for a fully reconsolidated joint quality, and it is suggested that a pin-offset in the fiber direction is beneficial for a fiber-friendly joining process.

Feasibility Study of Laser-Assisted Incremental Forming for Carbon Fiber Reinforced Thermo Plastic Based on 3D-CAD Data

A three-dimensional (3D) printer can be used to form various shapes in a single process. However, shell shape formation is difficult because of the low adhesion strength between the layers in 3D printing, and sufficient stiffness cannot be maintained. Therefore, the authors focused on laser-assisted incremental forming, which enables the formation of shell shapes from sheet materials, and used carbon fiber reinforced thermo plastic (CFRTP) for the samples. In the study, a laser-assist incremental forming system based on 3D computer-aided design (CAD) data was developed. The system comprises computer-aided manufacturing (CAM) system, which generates a tool path based on CAD data and evaluates the formability between the CAD data and 3D-scanned data, including alignment compensation. The feasibility of the developed system was demonstrated through a set of forming experiments.

Effect of the Fiber Content on the Quality of the Plastic Injection Molding Product

Fiber-Reinforced Thermoplastic (FRT) is widely used in plastic injection molding products. In this paper, the effect of fiber concentration on the quality of the plastic injection molding product is considered numerically. PA6 plastic materials, Schulamid 6, with different Glass Fiber (GF) contents, i.e., 15wt%, 30wt%, and 50wt% are selected for the same part and mold designs and process conditions. The warpage of the plastic product, the pressure loss inside the cavity, the plastic density, the packing pressure, and the volumetric shrinkage were investigated. The governing equations and the boundary conditions are numerically solved by the CAE software for injection molding products with the control volume method in a 3D transient system. The results indicate that the higher the content of glass fiber in Schulamid 6, the lower the fluidity of the melted plastic in the Schulamid 6 between different glass fiber contents of 15wt%, 30wt%, and 50wt%. Consequently, the pressure loss in the cavity is highest for Schulamid 6 GF50. Moreover, high GF concentration enhances the plastic density and leads to low volumetric shrinkage and also small warpage inside the product. Therefore, the quality of the part could be improved with the high GF concentration in plastic, i.e., Schulamid 6 GF 50.

Mesoscale failure analysis of the hybrid structure by injection overmolding after compression process

The injection overmolding after compression (IOAC) is a promising hybrid process that manufactures the load-bearing parts by assembling the fiber-reinforced thermoplastic (FRTP) laminate with FRTP ribs. However, the size effects of interfacial mechanical interlocking on failure evolution are unclear. A mesoscale model of representative volume element, including the fibers, matrix, matrix-fiber interface as well as the IOAC interface, is established to predict its failure process and failure modes. The influence of IOAC interface waviness (height, width, and thickness) on shear and tensile strength is investigated. The results show that the increased height and thickness positively affect the shear and tensile strength, while the increased width has a negative effect. The crack originates from the wave trough of waveform interface at tensile loading, while it originates between the wave trough and the wave crest under shear loading. The primary failure modes of IOAC structure include interface fracture, matrix damage, and matrix-fiber interface debonding. The results in this work can guide the interface design by changing its waviness through the surface pretreatment and IOAC process control. Visualizing the failure process of IOAC structure can provide some information difficult to capture in tests, which is useful in predicting the failure degree and location of IOAC structure in engineering application.

Improving bonding strength of Al/CFRTP hybrid joint through modifying friction spot joining tools

Pinless friction spot joining (FSpJ) has proven to be a competitive friction-based joining technique for fabricating metal/carbon fiber-reinforced thermoplastics hybrid joints. The present study investigated the feasibility of tool modification to improve the property of the silane-coated 6061-T6 Al alloy and carbon fiber-reinforced polyamide-6 (CF/PA6) FSpJ joint. The interfacial structure, bonding strength and fracture surface of the joints obtained by four tools, viz, old flat (OT), new flat (NT), concave-shaped (CT) and ring-shaped tools (RT) with different rotation speeds, were analyzed and compared. An experimentally validated three-dimensional finite element model was also built to help understand FSpJ process. Despite modifying the tool shape, covalent bonding predominated the interfacial bonding force where the formation of nanoscale diffusion layers was witnessed with no new type of covalent bonds generated. The resultant fracture surface was dominated by the cohesive failure mode, suggesting strong chemical bonding between the re-solidified resin and silanized Al surface. The decrease in tensile shear force in the case of NT was due to the extensive formation and coalescence of microscale voids and porosities. This was mitigated by using CT and RT tools, from which the heat input was controlled leading to a more homogenized heat field. From the combined evaluation of thermal process and mechanical characteristics, CT tool was recommended for the FSpJ of Al and CF/PA6 because it offered a more uniform temperature distribution and improved macro-mechanical interlocking at the interface with good wetting conditions, sufficient chemical reaction and effective joining area, and lower tensile residual stresses, in comparison with other tools, and hence showed the highest shear force.

Influence stacking sequence and heat treatments on the out-of-plane mechanical properties of 3D-printed fiberglass-reinforced thermoplastics

Additive manufacturing of composite materials is a promising technology. It could solve one of the most critical drawbacks of 3D-printed fiber-reinforced thermoplastics: their low out-of-plane mechanical properties. Due to this factor, it is still unknown how most design and manufacturing parameters affect the out-of-plane properties of composite materials. As a solution, this paper proposes an experimental methodology to characterize out-of-plane printed composite materials. For this purpose, existing standards for traditionally fabricated composites are adapted, investigated, and validated for 3D-printed laminates reinforced with long fibers using the fused filament fabrication technique. Consequently, the methodology is employed to study the impact of stacking sequence and heat treatment conditions on the composites’ out-of-plane mechanical properties. The main results showed that increasing the thickness between stacking layers increases the mechanical response due to reducing the number of fiber/matrix interfaces and, consequently, the reduction of porosity. Compared to the initial sample, a heat treatment at 175 °C for 6 h increased the interfacial strength by 101.09% and reduced the porosity in the fiber produced by the additive manufacturing process by 72%.

Tensile Response of Fibre-Reinforced Plastics Produced by Additive Manufacturing for Marine Applications

The present study makes a consistent attempt to evaluate promising additive manufacturing (AM) processes and materials for marine structural applications, paving the way for the development of additively manufactured light-weight composites. The main objective is to analyse the structural performances of fibre-reinforced plastics (FRP) produced by AM for marine applications. In particular, the tensile response of chopped and continuous carbon-fibre-reinforced thermoplastics have been investigated through destructive and non-destructive testing, considering the influence of AM process settings and thermal post-manufacturing treatments. The results demonstrate that continuous fibre-reinforced thermoplastics produced by AM are potentially suited to marine structural applications, since their tensile capacity is superior to the minimum imposed by the Classification Society Rules. However, the mechanical properties of additively manufactured FRP are currently lower than conventional composites. The continuous carbon fibre reinforcement is far more effective than the chopped one, and the additive manufacturing deposition pattern significantly influences the structural capacity. The annealing post-manufacturing treatment enhances the mechanical properties by approximately 10%, decreasing material ductility and manufacturing defects.

Investigation of the influence of multiple thermoforming processes on the properties of continuous fiber-reinforced thermoplastics to enable structural reuse

Fiber-reinforced plastics (FRP) are finding more and more applications in many industrial sectors. The growth in material use simultaneously leads to larger volumes of end-of-life materials and FRP are generally difficult to recycle. This also applies to FRP with a thermoplastic matrix. One possibility is the approach of structural reuse by reshaping continuous fiber-reinforced thermoplastics (organosheets). In this process, end-of-life (EOL) components are remelted and formed back into semi-finished products. However, the multiple thermal processes can damage the matrix. In addition, the frequent forming processes lead to fiber breaks and displacements of the reinforcement architecture. In order to assess the level and impact of matrix and fiber damage, various forming and reforming processes were performed on selected materials, which were then investigated using attenuated total reflectance (ATR) spectroscopy and tensile tests. The results of the ATR spectroscopy show no evidence of damage to the matrix. In contrast, slight to moderate decreases in the characteristic values as a result of multiple deformations can be observed in the results of the tensile tests. However, the experiments and material tests show the potential that this approach can produce high quality secondary materials. A comparison is made here with mechanically recycled and compounded injection molding materials.

Effect of reprocessing on the service life properties of glass fiber-reinforced in-house polypropylene waste composites

Reprocessing of synthetic fiber-reinforced thermoplastics for reuse in the design of structural components applications is important owing to their non-biodegradability. This study evaluates the effect of reprocessing on the service life properties of in-house polypropylene wastes reinforced with E-glass fiber. Composite materials containing 10 mm length glass fiber (GF) and recycled polypropylene were manufactured with 10 wt% GF and subjected to five reprocessing cycles via extrusion and compression molding under similar conditions. Properties such as mechanical, melt flow index (MFI), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis were used to analyze the effect of reprocessing on the composites. The results obtained revealed that the composites’ properties diminished with successive reprocessing. The thermal study showed reductions in the thermal stabilities with a drop in onset degradation temperature from 338.07 to 245.15 °C after five runs, indicating an increase in the polymer chain molecular movement and less rigidity due to shorter chains provided by X-ray diffraction analysis with reduced peak intensities, average crystallite sizes, and degree of crystallinities but no destruction of the main functional groups was observed with the spectral studies. An increase in the MFI (6 g/10–17.88 g/10 min) indicated the possible loss of complex viscosity and damage in molecular weight for the reprocessed matrix. Reinforced in-house PP plastics can, therefore, be reprocessed twice only for the same product except with the addition of either virgin PP or other materials to compensate for the lost properties and help manufacturers save costs.

Role of confinement in the shear banding and shear jamming in noncolloidal fiber suspensions.

The jamming effect is critical in processing short fiber-reinforced thermoplastics (FRTs). Fiber jamming can induce discontinuous shear thickening (DST) in simple shear and result in fiber-matrix separation in more complex flows such as injection molding and compression molding of FRTs. The confinement effect commonly induces local jams and strongly enhances fiber jamming. However, the transient evolution of local fiber jams under confinement and its correlation with the tumbling of fibers are still elusive. In this study, we adopted rheo-PIV (particle image velocity) techniques to study this effect for glass fiber-reinforced thermoplastics (FRTs). The translational and tumbling motion of fiber were determined during rheological measurements, and the distribution of fiber orientation was determined by X-ray CT. Three shear banding regions appeared after the viscosity overshoot under high shear stress in suspensions with high fiber content, which was associated with the three regions of fiber orientation across the gap due to confinement. Shear banding was ascribed to the different tumbling speeds across the gap because of the different initial orientations and different wall confinements near and far from the wall. The local shear thickening and jamming behavior became most significant under intermediate confinement, and were affected by shear strain, shear stress, and fiber contents. 3D state diagrams were constructed to show the confinement effect on the evolution of shear banding and jamming.

Defect detection for large-series automated fibre placement using a neural network-assisted machine vision approach

Tailored reinforcement structures from carbon fibre-reinforced thermoplastics show high potential for minimizing material volume, wall thickness and overall lightweight potential in plastic parts. Integrating small amounts of carbon fibre unidirectional tape material in injection-molded parts has the ability to maximize lightweight potential. Through a novel manufacturing approach developed by AZL, automated fibre placement becomes viable in large-series manufacturing by reducing cycle times down to 5 seconds. Therefore reliable, defect-free manufacturing becomes vital for economic competitivity. In this paper, a novel approach for defect detection using computer vision in combination with neural networks is developed and analysed for applicability in large-series manufacturing. Different occurring defects during processing are detected and classified. Subsequently, classification accuracy is analysed in regard to the predefined defect classes.

Relationship between interfacial shear strength and impact strength of injection molded short glass fiber-reinforced thermoplastics

Short glass fiber-reinforced thermoplastics (SGFRTPs) are being used to reduce carbon dioxide emissions from transportation equipment, especially domestic vehicles, because of their properties and because they are lighter than metal or ceramic materials. Interfacial shear strength (IFSS) strongly affects mechanical properties of SGFRTPs, such as the impact strength. In recent years, investigations of IFSS and impact strength have been very active. Positive correlation between these properties is often reported, but no clearly defined quantitative relation has been found. This study used the short beam method and the notched Charpy impact test to elucidate IFSS and the impact strength of injection-molded SGFRTPs with varying fiber contents: IFSS decreases concomitantly with increasing fiber content; the notched Charpy impact strength increases concomitantly with increasing fiber content. Fiber pull-out occurred along the entire fracture surface. Findings confirmed that fiber pull-out occurred with both crack initiation and propagation, indicating that energy absorption in the impact test was entirely attributable to the frictional energy necessary for fiber extraction. Based on this conclusion, a mechanical model was developed to explain the notched Charpy impact strength of SGFRTP injection molded products in terms of their IFSS, pull-out fiber length, and fiber orientation angle. The impact strength calculated using the predicted results shows good agreement with the experimentally obtained results.

Response of carbon/PEEK automotive driveshafts with/without an inner isotropic layer at high temperature considering temperature-dependent material properties

Lightweight fibre-reinforced thermoplastic (FRTP) driveshafts are ideal for automotive applications. In this work, material and buckling failures of FRTP driveshafts subjected to torsion at elevated temperature are analysed by finite element modelling. Critical speed at increasing temperature is also quantified. The driveshafts comprise unidirectional carbon/polyetheretherketone (PEEK) layers with/without an inner layer of aluminium or unreinforced plastic. Temperature-dependent material properties are considered. The results demonstrate achievable performance of the fully carbon/PEEK and hybrid driveshafts, which are compared with traditional alloy counterparts. The carbon/PEEK shaft exhibits marked temperature sensitivity but satisfies the design requirements at high temperature with significant weight reduction. A hybrid shaft composed of carbon/PEEK layers over-wrapped onto an aluminium tube provides a compromise in terms of superior buckling resistance and critical speed but reduced material failure safety factor. Utilising a thick layer of unreinforced plastic to reduce fibre volume may only be suitable for low-temperature, low-speed applications.

On the feasibility of joining additively-manufactured 316L stainless steel and poly-ether-ether-ketone by ultrasonic energy

• The joining of additively manufactured metal-polymer parts via U-Joining was proven. • Through-the-thickness reinforcements improved the joint mechanical performance. • Ultimate lap-shear forces up to 3.2 ± 0.2 kN were achieved by the produced joints. • Polymer penetrated metal surface cavities, improving micromechanical interlocking. • Fractography analyses showed a mixture of cohesive and adhesive failure. Ultrasonic Joining (U-Joining) process is a friction-based joining technique capable of producing through-the-thickness reinforced (TTR) hybrid joints between surface-structured metals and unreinforced or fiber-reinforced thermoplastics. Previously, the process feasibility has been demonstrated to join injection-molded Ti-6Al-4V and extruded unreinforced and laminated glass-fiber-reinforced polyetherimide structures, resulting in joints with improved out-of-plane strength and fatigue performance. However, there is an unexplored field concerning the joinability of additively manufactured (AM) metal and polymer parts via U-Joining. AM allows the production of structures with complex designs, but joining AM parts can represent a challenge as defects might appear along the process, such as delamination. In this work, the feasibility of joining laser powder bed fusion (LPBF) 316L stainless steel and fused filament fabricated (FFF) poly-ether-ether-ketone (PEEK) via U-Joining is demonstrated. Optical and scanning electron microscopy showed that TTRs were fully inserted into the polymer and that molten PEEK could flow around and penetrate metal surface cavities, thereby improving the macro- and micromechanical interlocking between the parts. Finally, quasi-static lap shear tests were performed, showing an improvement in the ultimate lap shear force up to 2.8 times (from 1.1 ± 0.2 kN to 3.2 ± 0.2 kN) and the displacement at break up to 2.1 times (from 0.7 ± 0.1 mm to 1.45 ± 0.2 mm) when compared to unreinforced (flat pinless) reference joints produced with the same energy input.