Joint Shear Research Articles

A progressive damage model to predict the shear and mixed-mode low-cycle impact fatigue life of adhesive joints using cohesive elements

A progressive damage model to predict the shear and mixed-mode low-cycle impact fatigue life of adhesive joints using cohesive elements

Mechanical properties of aluminum to steel dissimilar spot joints produced by cold metal transfer weld-brazing

Spot joints between aluminum and steel sheets were produced by cold metal transfer arc welding using an AlSi3Mn alloy low melting point filler wire. The current study found that by using optimal welding conditions, the thickness of the joint interface was significantly reduced compared to previous studies. The interface thickness increased from a few nanometers at the center of weld to 1.7 micrometers (1.2 mm from center of weld) at periphery of weld. The reduction in joint thickness helped to achieve better joint properties. The tensile shear and fatigue properties of the spot joints were evaluated in conjunction with interrupted mechanical tests to determine the fracture mechanisms. This study investigates the fatigue properties and fracture mechanisms of cold metal transfer arc spot joints, which has not been done previously. The tensile shear fractures exhibit primarily interfacial fracture passing through an intermetallic compound layer at the joint interface. However, three different modes of fractures are observed during fatigue tests, including interfacial fracture, sheet fracture, and mixed-mode fracture. Interrupted fatigue tests reveal numerous crack initiation in pores/particles in the deposited weld metal and coagulation of those cracks leads to sheet fracture during the fatigue tests. Sheet fracture mode fractures are mainly observed during high cycle fatigue conditions.

State-of-art summary of the strength hierarchy assessment and its applications

Strength hierarchy assessment is a method developed to be able to identify the governing failure mechanisms at reinforced concrete (RC) beam-column joints. The main failures that can be identified in this method are: i) beam plastic hinge; ii) column plastic hinge/shear failure; iii) beam-column joint shear failure. Through the identification of the governing failure mode in a joint, the validity of the capacity design principles can be checked for the considered RC beam-column joint. The obtained observations can then be used in finding the most optimal repair/strengthening application. This method has been going through updates and developments in the last decade and new applications have emerged. In this article, a state-of-the-art summary of the procedure is reported with its most recent updates as well as its practical engineering applications.

A consecutive joint shear strength model considering the 3D roughness of real contact joint surface

A consecutive joint shear strength model for soft rock joints is proposed in this paper, which takes into account the degradation law of the actual contact three-dimensional (3D) roughness. The essence of the degradation of the maximum possible dilation angle is the degradation of the 3D average equivalent dip angle of the actual contact joint asperities. Firstly, models for calculating the maximum possible dilation angle at the initial and residual shear stress stages are proposed by analyzing the 3D joint morphology characteristics of the corresponding shear stages. Secondly, the variation law of the maximum possible dilation angle is quantified by studying the degradation law of the joint micro convex body. Based on the variation law of the maximum possible dilation angle, the maximum possible shear strength model is proposed. Furthermore, a method to calculate the shear stiffness degradation in the plastic stage is proposed. According to the maximum possible shear strength of rock joints, the shear stress-shear displacement prediction model of rock joints is obtained. The new model reveals that there is a close relationship between joint shear strength and actual contact joint roughness, and the degradation of shear strength after the peak is due to the degradation of actual contact joint roughness.

Experimental investigation on microstructure and surface morphology deterioration of limestone exposed on acidic environment

Understanding evolution of microstructure and surface morphology is essential for studying the strength of building material in acidic enviorment. In this study, the microstructure of limestone samples immersed in acidic solutions of varying pH values was evaluated by nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM), while the joint surface morphology evolution process was determined by three-dimensional (3D) scanning experiments. Further, direct shear tests on the immersed jointed samples were conducted for shear properties analysis. It is found that the pore size distribution gradually changes from nanopore to micropore with the decrease in pH value, while the single pore area and perimeter increased and the fractal dimension decreased. Therefore, the increased pore distribution, enlarging in area, and change in the shape of the pores altered the microstructure and caused the increase in porosity. Also, with the decrease in pH value, the decrease rate of 3D relative fluctuation height, angle, and 3D area ratio increase. The 3D average fluctuation angle decreases the most, whereas the 3D area ratio decreases the least. In an acidic environment, the 3D surface morphology is significantly influenced by the 3D average fluctuation angle, which eventually changes joint roughness. Under the condition of acidic underground water, the microstructure of the joint wall and surface morphology of the joint degraded, thereby affecting the joint shear behavior. Therefore, the degradation of joint roughness coefficient and joint wall compressive strength should be considered for evaluating the joint mechanical properties in an acidic environment.

Optimized AgCuSnTi filler alloy for brazing of diamond/copper combination used in microwave windows: Microstructure and mechanical performance

For the fabrication of diamond microwave windows, a solid joining of diamond with copper rings is critically required. In this work, the AgCu-mSn-nTi filler alloys were designed to braze the diamond and copper. The typical joint microstructure was characterized and its formation mechanism was unveiled. The effect of Ti or Sn fraction on the microstructure and joint shear strength was examined. Finally, an inherent relationship between the microstructure and joint bond strength was clarified. The joint average shear strength optimized reached 256.1 MPa when brazed using AgCu–10Sn–1Ti. With more Ti addition, excessive CuSn3Ti5 compounds produced early failure in the interlayer. Increasing Sn content helped to densify the interlayer. However, rigid Cu5Sn formed declined the joint strength when Sn was over 15 wt%. The work performed provided an optimized filler composition for low-temperature joining of diamond and copper and would guide the fabrication of diamond windows theoretically and technologically.

Effect of 0D and 1D ZnO nano additive reinforced Sn-3.0Ag-0.5Cu solder paste on InGaN LED chip/ENIG joints

Nanocomposite solder has been recognized as an excellent strategy to improve the reliability of solder joints. This study attempts to find the effects of ZnO nanoparticles (NP) and nanowires (NW), on the LED/Sn3.0Ag0.5Cu joint reliability. Varying amounts of ZnO NP and NW are dispersed into solder using a high-speed centrifugal paste mixer and LED/solder joints were assembled via paste printing and reflow technique. Until 0.2 wt %, adding NP and NW improved the spreading ratio of SAC 305 paste by 8.7 % and 11.1 %. However, due to ceramic/metal surface instability, higher addition declined the spreading ratio. Both NP and NW suppressed the (Cu, Ni)6Sn5 intermetallic compound (IMC) formed at the LED/solder joint. Dispersion strengthening provided by NP and NW improved the joint shear strength by 28.2 % and 31.1 %, respectively. The Weibull modulus and 75 % survival probability improved consistently with increasing ZnO NW addition, displaying homogeneity in shear strength and reliable LED/solder joints.

The temperature-dependent shear strength of ice-filled joints in rock mass considering the effect of joint roughness, opening and shear rates

Abstract. Global warming causes many rockfall activities in alpine mountains, especially when ice-filled joints in the rock mass become thawed. The warming and thawing of frozen soils and intact rocks have been widely studied in the past several decades; however, the variation of shear strengths of ice-filled joints is not fully understood. In this study, a series of compression–shear experiments were conducted to investigate the shear strength of ice-filled rock joints by considering the effects of joint roughness, temperature, opening, shear rates and normal stress. The joint roughness can improve the shear strength of ice-filled joints. However, the contribution of joint roughness is controlled by some noticeable bulges instead of the joint roughness coefficient (JRC) index. The peak shear strength of the ice-filled joint linearly increases with the increasing aggregation of rupture ice area before these noticeable bulges. As the joint opening increases, the effect of joint roughness decreases, and the shear strength of ice-filled joints tends to be equal to the shear strength of pure ice. In addition, the shear strength quickly reduces with increasing temperature from −15 to −0.5 ∘C. The shear failure mode changes from shear cracking of joint ice to the shear debonding of the ice–rock interface above −1 ∘C. Increasing shear rate decreases the shear strength of ice-filled joints because the joint ice displays the brittle failure phenomenon at a high shear rate. The peak shear strength of the ice-filled joint linearly increases with the increase in normal stress. Moreover, it is also proved that the Mohr–Coulomb criterion can be used to characterize the shear strength of ice-filled joints under different normal stresses. This research can provide a better understanding of the warming degradation mechanism of ice-filled joints by considering the abovementioned important influencing factors.

Assessment of Modal Characteristics of Steel–Concrete Composite Girder Bridge with V-Shaped Piers

As the standards of bridge design and construction continue to improve, more and more combination bridges are being put into use. The public’s demand for aesthetically pleasing bridges is also increasing, making it necessary to use the special structure of steel–concrete combinations, continuous V-shaped piers, and continuously stiffened bridges. This structure has the structural and mechanical characteristics of both a continuous girder and a V-shaped pier bridge. The span can be reduced to a certain extent because the support of the V-shaped piers can be applied directly to the main girder. The spanning capacity of the bridge is generally greater than that of a combined steel–concrete girder bridge with vertical piers. The whole bridge is continuous, without expansion joints, making it more stable and safe for traffic. At present, research on this structural bridge type is not yet complete. In this paper, the structural system and dynamic characteristics of this bridge are investigated in the context of real-life engineering. Firstly, the self-vibration characteristics of the three structures were analyzed, and their effects on the self-vibration characteristics were studied by varying the height of the crossbeam at the V-shaped piers’ support, the main beam stiffness, and the V-shaped piers’ stiffness in the three structures. The results show that the increase in main beam stiffness can effectively improve the vertical stiffness of the three structures, with the most obvious effect on structure one and the least effect on structure two; the increase in V-shaped pier stiffness causes a huge improvement in the transverse stiffness of the three structures. Subsequently, a two-unit rod system model of the background bridge was established using the finite element method, and the original model was improved by calculating the equivalent shear stiffness of the shear nail group so that it could simulate the shear joints more accurately. The effects of the shear connectors on the self-vibration characteristics of the steel–concrete combined continuous beam–V-shaped piers and continuous rigid-frame bridge were investigated through theoretical analysis and finite element simulation. It was found that due to the existence of flexible shear connectors, the interface between the steel beam and concrete slab in the combined beam has a slippage effect which causes the deformation to become unsynchronized, and there is a certain difference between vibration patterns. The stiffness of the shear connectors has a certain effect on the self-vibration frequency of the bridge. The damage to the local shear connectors does not have a large effect on the self-vibration frequency of the overall structure, but the damage to the shear connectors at the beginning of the connection between the V-shaped piers and the main beam is greater than that of the other areas. Damage to shear joints should be given special consideration in comparison to other areas.

Discontinuous bifurcation of FRCC with zero-thickness interface modeling

In this work, firstly a fracture-based interface constitutive theory, aimed at simulating the cracking mechanisms of Fiber Reinforced Cementitious Composites (FRCCs), is presented. The discontinuous formulation assumes a hyperbolic maximum strength criterion in terms of normal and shear joint stresses. The latter are evaluated on each crack front to simulate the failure behavior of plain and FRCC systems. A non-associated plastic flow rule, in conjunction with a post-cracking softening law, is defined to complete the modeling approach. On the other hand, the use of the most-classical Mixture Theory is followed for taking into account the actions of fibers in concrete matrix. The bridging mechanisms between fibers and active cracks are defined in terms of fiber-to-concrete bond–slip rule and dowel effects. Secondly, a normalized Cracking Indicator (CI) for discrete crack is proposed in the spirit of Hill’s indicator for loss of stability of inelastic continua, to effectively evaluate the most critical direction for further loading in terms of the resulting energy release and crack opening, while accounting for the fiber direction and content. After presenting the constitutive theory and, particularly, the novel concept of the CI, numerical analyses at constitutive level are performed to evaluate the evolution of the fracture energy, post-peak strength, and critical cracking directions under variable fiber contents. Different load scenarios are evaluated, and the numerical predictions are compared with experimental data.

Experimental investigation of textile reinforced concrete thin-wall panel bolted connections

Textile Reinforced Concrete (TRC) is a composite material that combines fine-grained concrete with textile fibers to create a new building material with improved mechanical properties. TRC, an innovative thin-wall precast panel construction solution, offers excellent tensile strength, crack resistance, and durability. The behavior of bolted joints in textile-reinforced concrete thin-wall panels was experimentally studied in this research. The investigation focused on three types of connections: moment joints, shear joints, and half-box connections. The study aimed to examine the structural performance of these joints under different loading conditions and identify the failure modes. Ten specimens were tested, and the results were analyzed to determine the relationship between applied load and joint behavior. This research provides valuable information for the design and optimization of bolted joints in textile-reinforced concrete thin-wall panels.

Study on fracture conductivity under dynamic sand laying mode

The existing API static sand laying fracture conductivity evaluation experiment ideally believes that the proppant is evenly and statically laid in the fracture, without considering the actual fracturing conditions, the proppant migrates along the fracture and leaks into the formation. In order to more truly simulate the actual fracturing conditions, the experimental study of fracture conductivity is carried out by using the dynamic conductivity testing device, which is closer to the field reality than static sand laying. The parameters of the indoor dynamic sand laying diversion experiment are determined by the similarity criterion and the indoor fracturing fluid rheology experiment. The orthogonal experiment and the shear support fracture dynamic diversion experiment are designed to study the effects of pumping displacement, fracturing fluid viscosity and construction sand ratio on the dynamic sand laying diversion ability, and optimize the on-site construction parameters. The experimental results show that increasing the construction displacement, sand ratio and selecting the appropriate fracturing fluid viscosity have a positive impact on the fracture conductivity of dynamic sand laying support, among which the sand ratio has the greatest impact. Under the condition of effective closure stress of the reservoir, the natural non sanding shear fracture and the dynamic paving shear fracture with 12% sand ratio have no conductivity, which is difficult to meet the requirements of field production. When the 1-3 mm shear joint is dynamically paved with 18% sand ratio and the closing pressure is 30-70 MPa, the conductivity is positively correlated with the sand concentration, but it is nonlinear with the shear dislocation. The shear joint pump injects 18% proppant with sand ratio, which can support the fracture under high closing pressure and provide conductivity. It is necessary to appropriately increase the pump injection ratio of more than 18% sand ratio according to the proportion of on-site shear cracks to effectively support shear cracks.

Behavior of corrosion damaged non-seismically and seismically detailed reinforced concrete beam-column sub-assemblages under cyclic loading

Corrosion of reinforcement requires immediate redressal as it poses a severe threat to the serviceability and seismic performance of the existing reinforced concrete structure. Taking this into consideration, the current study presents an experimental assessment of the seismic behavior of corroded exterior beam-column joint sub-assemblage under quasi-static reverse-cyclic loading. A total of eight exterior beam-column joint specimens i.e., four having traditional non-ductile transverse reinforcement detailing as per IS 456:2000 and the remaining specimens ductile detailed according to IS 13920:2016 were cast. One specimen from each detailing regime was tested uncorroded and acted as a control specimen while the remaining six specimens were subjected to varying levels of accelerated corrosion. The experimental results illustrated that the sliding phenomenon in the hysteresis curve gradually increases and a drastic fall in energy dissipation, stiffness, and post-yield displacement were seen as the corrosion progresses within reinforcing bars. The failure mode shifted from diagonal joint shear failure observed in control specimens to longitudinal and major flexural cracking failure along the beam reinforcement. First-level corroded specimens showed a slightly increased ductility factor, indicating that low levels of corrosion may improve ductility. However, after 10% corrosion, all corroded specimens showed poor seismic performance and the cumulative energy dissipation curve tends to go flat at approximately half the displacement as compared to control specimens. The cumulative energy dissipation of non-ductile and ductile specimens damaged to the most severe level of corrosion in this study was only 0.3 and 0.4 times that of respective control specimens. In general, the ductile detailed specimens showed better seismic performance than the corresponding non-ductile detailed specimens owing to the closer arrangement of stirrups.

Seismic Retrofitting of Nonseismically Detailed Exterior Reinforced Concrete Beam-Column Joint by Active Confinement Using Shape Memory Alloy Wires

It is widely accepted that the seismic retrofitting of nonseismically detailed reinforced concrete beam-column joints (BCJs) in reinforced concrete (RC) frame buildings is an urgent necessity due to its high vulnerability and potential consequences in seismic events. As a result, considerable effort has already been put into developing efficient and practical retrofitting solutions for such BCJs. Most of the existing techniques, however, are based on either passive confinement techniques, for example, fiber reinforced polymer (FRP) wrappings, or involve a considerable joint enlargement, which, in many cases, is undesirable. In this study a new technique of retrofitting BCJs is proposed by employing a more effective method of confinement (i.e., active confinement), utilizing the shape recovery feature of shape memory alloys (SMAs). To evaluate the performance of the proposed retrofitting scheme, experimental tests were conducted on full-scale BCJ specimens. The efficacy of the proposed retrofitting scheme is evaluated in terms of enhancement in strength, ductility, energy dissipation capacity, damage reduction in the specimens, and ease of application. The results from this study suggest that the proposed retrofitting scheme could be effectively used in achieving the full capacity of the joints corresponding to beam yielding and consequently enhances the energy dissipation capacity of the system significantly. The test results demonstrated that the proposed retrofitting scheme performs excellently in reducing the joint shear strain (core damage) (to almost zero or negligible) and also in retaining the full axial load carrying capacity of the column, even at very large drift values. The proposed retrofitted scheme could also be conveniently used in cases where the capacity ratio of column-to-beam needs to be improved.

Experimental study on shear performance of bond-tooth dry joints in prestressed assembled concrete beams

Assembled concrete bridges have the advantages of scale, high quality, and low requirements for the surrounding environment. However, assembled concrete beam splice joints have problems such as complex assembly and high transportation requirements. For this reason, this study proposes a large key-tooth shear key to solve the problems of low shear bearing capacity and complex collocation of conventional concrete shear keys. To study the shear capacity of the large key-tooth shear key, six large key-tooth shear key specimens were designed and tested in direct shear under monotonic vertical load. From the structure of large key-tooth concrete shear keys, the analysis focuses on the damage modes and damage criteria of large key-tooth shear keys. The effects of shear key height, key tooth depth to height ratio, number of key teeth, and concrete strength on the shear performance of assembled bridge shear keys are investigated, and the load-carrying capacity variation law of large key tooth concrete shear keys under different working conditions is explored. In addition, the parameters of the nonlinear finite element concrete material principal model and steel principal model were used to perform finite element analysis of precast assembled concrete dry joint shear keys, and the damage modes of shear keys under various working conditions were explored. Multiple linear regression equations were established to evaluate the load-carrying capacity of concrete shear keys with large key teeth and to obtain the weak surface of the structure. The three-dimensional finite element model established can well simulate the structure of large bond-tooth shear keys and more accurately assess the damaged state of shear keys for application in actual structures and design of more reasonably stressed members.

E-Defense 2015 ten-story building: beam–column joint assessment according to different code-based design

Recent devastating earthquakes worldwide pointed out the importance of seismic detailing and their influence on the observed damage and subsequent repairability of reinforced concrete buildings. Several studies and post-earthquake observations remarked the role of beam–column joints (BCJs) on the global building response and the effectiveness of transverse reinforcement in increasing the joint shear strength and the ultimate deformation. Although number of experimental and theoretical studies focused on the seismic response of BCJs, their mechanical behaviour is still a discussed topic. This resulted in number of design approaches available in worldwide code or standards that lead to different quantity of joint stirrups. This study focuses on the response of BCJs of a 10-story prototype building designed according to Japanese standards and tested in 2015 on the E-Defense shaking table. First the damage assessment at global (building) and local (joint) level is performed at increasing intensities and considering the building in the base slip and base fixed configurations. A refined numerical model is then developed and validated against global and local experimental results. Then, the joint stirrups are re-designed according to different international standards (ACI, EC8, NZS) and different numerical models are developed. The numerical results are then compared in terms of interstorey drift demand and joint shear strain. Finally, a comparison in terms of expected damage varying the design approach of joint stirrups is proposed.

Dynamics of Two-Link Musculoskeletal Chains during Fast Movements: Endpoint Force, Axial, and Shear Joint Reaction Forces

This study provides a dynamic model for a two-link musculoskeletal chain controlled by single-joint and two-joint muscles. The chain endpoint force, and the axial and shear components of the joint reaction forces, were expressed analytically as a function of the muscle forces or torques, the chain configuration, and the link angular velocities and accelerations. The model was applied to upper-limb ballistic push movements involving transverse plane shoulder flexion and elbow extension. The numerical simulation highlights that the shoulder flexion and elbow extension angular acceleration at the initial phase of the movement, and the elbow extension angular velocity and acceleration at the later phase of the movement, induce a proportional medial deviation in the endpoint force direction. The forearm angular velocity and acceleration selectively affect the value of the axial and shear components of the shoulder reaction force, depending on the chain configuration. The same goes for the upper arm and elbow. The combined contribution of the elbow extension angular velocity and acceleration may give rise to anterior shear force acting on the humerus and axial forearm traction force as high as 300 N. This information can help optimize the performance and estimate/control of the joint loads in ballistic sport activities and power-oriented resistance exercises.

Experimental and theoretical study on seismic behavior of slab-wall joints in a new large-span slab-shear wall structural system

This paper proposes a new structural system named large-span slab-shear wall structure, which has prominent advantages in the architectural function and structural construction compared to the traditional shear wall structure. Due to the larger span and greater thickness of slabs, as well as the elimination of many beams and internal walls, the thick slab-shear wall joint becomes a key component in the new structure. This paper focuses on three typical types of thick slab-shear wall joints and conducts cyclic loading tests to reveal their seismic performance, including the exterior joints on the top floor (three l-shaped specimens), exterior joints on the intermedia floors (two T-shaped specimens), and interior joints on the top floor (two T-shaped specimens). Variables including the anchorage method of the slab bars and the reinforcement ratio of the walls are studied. Thereafter, based on the test results, a new calculation method for the joint strength of the slab-wall joints is proposed based on the strut-and-tie model from ACI318-19. The test results demonstrate that the proposed three types of slab-wall joints exhibit adequate strength and ductility under seismic loading despite the joint shear failure. The proposed simplified anchorage method can greatly reduce the congestion in the joint zone without weakening the seismic performance. The strut-and-tie model can provide an accurate prediction for the shear strength of the slab-wall joint zone.

Effect of sprinting velocity on anterior cruciate ligament and knee load during sidestep cutting.

The purpose of the study was to investigate the effect of an increase in sprinting velocity on the anterior cruciate ligament (ACL) load, knee joint load, and activation of femoral muscles using the musculoskeletal modeling approach. Fourteen high school male athletes were recruited (age: 17.4 ± 0.7years, height: 1.75 ± 0.04m, weight: 73.3 ± 8.94kg), with the right foot dominant and physical activity level of about 3-4h per day. The kinematics, kinetics, and co-contraction index (CCI) of the extensors and flexors of the right leg's femoral muscles were calculated. The anterior cruciate ligament load was estimated using the musculoskeletal modeling method. In the results, it was observed that the anterior cruciate ligament load (p < 0.017) increased as sidestep cutting velocity increased, resulting in increased adduction (p < 0.017) and the internal rotation moment of the knee joint. This was significantly higher than when sprinting at a similar velocity. The co-contraction index result, which represents the balanced activation of the femoral extensor and flexor muscles, showed a tendency of decrement with increasing sprinting velocity during sidestep cutting (p < 0.017), whereas no significant differences were observed when running at different sprinting conditions. Therefore, we postulate that factors such as knee joint shear force, extended landing posture with increasing sprinting velocity, internal rotation moment, and femoral muscle activity imbalance influence the increase of anterior cruciate ligament load during a sidestep cutting maneuver.

Ultrasonic Joining of Additively Manufactured Metal-Composite Hybrid Joints: A Comparison between Vertical and Horizontal Vibration Modes

Ultrasonic Joining (U-Joining) is a novel friction-based joining technique that produces through-the-thickness reinforced hybrid joints between surface-structured metals and thermoplastics. The process feasibility has been successfully demonstrated to join metals and unreinforced or fiber-reinforced polymer parts by applying horizontal vibration. However, intense tool wear was observed for the explored combinations of materials, which could diminish the mechanical performance of the produced joints and hinder the process application. These investigations left an unexplored field regarding the application of different vibration modes, which could represent good solutions to minimize the intense tool wear reported. Therefore, the present study aims to explore the application of vertical vibration and to identify possible advantages and disadvantages of this variation. The case-study combination of additively manufactured 316L stainless steel and 20%-short-carbon-fiber reinforced poly-ether-ether-ketone was selected for this purpose. Initially, a set of optimized joining parameters was obtained for the vertical variation following a one-factor-at-a-time approach. In a previous study, the joining parameters were already optimized for the horizontal mode, and the results were used for comparison purposes. Single-lap shear joints were produced using both optimized modes, and the process monitoring indicated that joints produced using vertical vibration reached a lower joining energy input for a given joining time. The produced joints were tested, and joints produced with the horizontal variation achieved higher ultimate lap shear forces than the ones achieved by the vertical ones: 3.6 ± 0.3 kN and 1.6 ± 0.3 kN, respectively. Microstructural investigations at the fractured surfaces showed that this difference is due to insufficient frictional heat generation at the metal-composite interface when vertical vibration is applied. Therefore, the temperatures reached during the joining cycle are not enough to melt the polymer completely at the interface, preventing a complete surface wetting of the metal and reducing the micromechanical interlocking and adhesion bond between the parts, thereby diminishing the mechanical performance of the produced joints.