Shear Tests Research Articles

Effect of rubber particles on mechanical properties of calcareous sand under large displacement shear

To reveal the influence of rubber particles on the mechanical properties of calcareous sand under the large-displacement shear effects of earthquakes and waves, indoor ring shear tests were conducted on rubber particle-calcium sand mixtures. The effects of rubber particle size and content on the mechanical properties of calcareous sand were studied via indoor ring shear test. Then, based on PFC3D, a numerical model of a ring shear test that can restore the shape of calcareous sand particles is established, and a mesomechanical analysis of mixed sand is carried out. The results showed that the effect of the rubber particle content on the crushing characteristics and strength of calcareous sand was significant and that the effect of the particle size was small. The rubber content causes a gradual decrease in the peak strength and particle crushing rate and increases the deformation stability of the mixed sand. The softening coefficient and relative crushing rate were significantly reduced to 0.01–0.06 and 0.28–1.2%, respectively, at 40% rubber content. The numerical simulations and experimental results were in good agreement. An increase in the rubber content significantly influences chain development, which explains the macroscopic mechanical properties of mixed sand at the fine level.

Computational comparison study of virtual compression and shear test for estimation of apparent elastic moduli under various boundary conditions.

Virtual compression tests based on finite element analysis are representative noninvasive methods to evaluate bone strength. However, owing to the characteristic porous structure of bones, the material obtained from micro-computed tomography images in the finite-element model is not uniformly distributed. These characteristics cause differences in the apparent elastic moduli depending on the boundary conditions and affect the accuracy of bone-strength evaluation. Therefore, this study aimed to evaluate and compare the apparent elastic moduli under various, virtual-compression and shear-test boundary conditions. Four, nonuniform models were constructed with increasing model complexity. For representative boundary conditions, two, different, testing directions, and constrained surfaces were applied. As a result, the apparent elastic moduli of the nonuniform model varied up to 55.2% based on where the constrained surface was located in the single-end-cemented condition. Additionally, when connectivity in the test direction was lost, the accuracy of the apparent elastic moduli was low. A graphical comparison showed that the equivalent-stress distribution was more advantageous for analyzing load transferability and physical behavior than the strain-energy distribution. These results clearly show that the prediction accuracy of the apparent elastic moduli can be guaranteed if the boundary condition on the constraint and loading surfaces of the nonuniform model are applied symmetrically and the connectivity of the elements in the testing direction is well maintained. This study will aid in precision improvement of bone-strength-indicator determination for osteoporosis prevention.

Appraisal of Bhatta Waste as an Admixture for the Stabilization of Fill Soil

Testing of soil and knowing its strength parameter’s is one of the basic components in construction. Testing of soil is carried out to find whether the existing soil can endure the burden of structure withheld upon it or not. In case of a weak soil, one can find difficult to pursue construction or any development project. While talking of solutions, there are many methods to improve its strength and properties: one of them which we decided to work on is ‘Appraisal of Bhatta Waste as an Admixture for the Stabilization of Fill Soil’. It’s a kind of cost effective & economical means of improving soil, as the basic material required for stabilization is Bhatta waste, which is normally easily available material. The main objective of our test is to check the effectiveness of Bhatta waste on mechanical properties of filled material. The testing comprised of performing Atterberg limit, UCS, direct shear test, sieve analysis, Moisture dry density and Permeability test. The Bhatta waste passing no. 40 sieve is mixed with fill soil and testing on different proportions was carried out. Summary was prepared for explanation of engineering properties of different proportions, while further testing on higher proportions is recommended.

Size effect and underlying microstructural mechanism in cyclic deformation behavior of nickel-based superalloy sheet

The nickel-based GH4169 superalloy is widely used in the aerospace field, which has desirable oxidation resistance and strength in extreme environments. However, the size effect and underlying microstructural mechanism in the cyclic deformation of the GH4169 sheet are still not fully elucidated, which affects the forming accuracy precision of thin-walled components. To this end, the cyclic mechanical properties and microstructural evolution of the GH4169 sheets with different thicknesses and grain sizes were systematically investigated via cyclic shearing tests. The superalloy sheet exhibits obvious early re-yielding, instantaneous softening and permanent softening during the cyclic deformation and these cyclic deformation behaviors are obviously affected by size effect. To rationalize the cyclic mechanical responses and size effect, transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) tests were conducted. The results indicated that the dislocation slip patterns are principally planar array slip and cross slip in the cyclic shearing deformation. Meanwhile, the annihilation of unstable dislocation and the presence of carbides led to the instantaneous softening. Moreover, the change of loading direction, the reduction of texture strength, the proportion of low-angle grain boundary (LAGB), and geometrically necessary dislocation (GND) density together result in the occurrence of permanent softening. Based on the comparative analysis of the microstructure evolution of superalloy sheets with different size factors, the underlying mechanism of size effect on cyclic deformation was clarified. The findings in the research combine the cyclic mechanical response and microstructure evolution closely in the cyclic deformation of superalloy sheets and deepen the understanding of size effect under complex loading paths.

Roughness Evolution of Granite Flat Fracture Surfaces during Sliding Processes

Roughness is an essential factor affecting the shear process of discontinuous surfaces, and the evolution of roughness is closely related to the mechanical behavior of discontinuous surfaces. In this paper, with the help of granite specimens, a direct shear test was carried out on flat fracture surfaces obtained by sawing in order to study the evolution of roughness with shear slip. During the tests, the roughness evolution was evaluated using the arithmetic mean, root mean square and power spectral density of the roughness. The variation in these parameters all indicate that the friction surface with large slip tends to be rougher, at least under the loading conditions in this paper. And the increase in normal force will enhance this process, while the loading rate seems to have little effect on the roughness evolution. Finally, the analysis of the power spectral density shows that the roughness evolution in the spatial frequency of the profile line is mainly reflected in the middle– and low–frequency part, while the high–frequency part corresponding to the microscopic roughness body does not change much throughout the shear process.

Shear Strengthening of Stone Masonry Walls Using Textile-Reinforced Sarooj Mortar

Most historical buildings and structures in Oman were built using unreinforced stone masonry. These structures have deteriorated due to the aging of materials, environmental degradation, and lack of maintenance. This research investigates the physical, chemical, and mechanical properties of the local building materials. It also presents the findings of an experimental study on the in-plane shear effectiveness of a modern strengthening technique applied to existing stone masonry walls. The technique consists of the application of a textile-reinforced mortar (TRM) on one or two faces of the walls. Shear loading tests of full-scale masonry samples (1000 mm width, 1000 mm height, and 350 mm depth) were carried out on one unreinforced specimen and six different cases of reinforced specimens. The performances of the unreinforced and reinforced specimens were analyzed and compared. We found that strengthened specimens can resist in-plane shear stresses 1.5–2.1 times greater than those of the unreinforced specimen; moreover, they demonstrate ductility rather than sudden failure, due to the presence of fiberglass and basalt meshes, which restrict the opening of cracks.

Simple double shooting approach with bisection for FRCM reinforced curved masonry prisms subjected to shear

In this study, curved masonry pillars reinforced with FRCM subjected to standard shear tests are analyzed through a novel mono-dimensional model, where failure is governed by Mode II. Three approaches with different accuracy are proposed: i) the first, where the outer matrix is neglected; ii) the second, where the inner matrix is assumed rigid; and iii) the third which considers both matrix layers. Matrix and fiber are assumed subjected to a monoaxial state of stress and exchange tangential stresses at the interfaces. The load is applied by incrementing the displacement at the free fiber edge. Material properties of matrix, fiber and interfaces are assumed constant on small portions of the bonded length. Non-linearity is considered penalizing the elastic modulus using the results of the previous time step. The substrate is assumed rigid. The substrate curvature influence is manifested through interface normal stresses, incorporated into the bond-slip constitutive behavior via the Mohr-Coulomb law. The normal stresses can be determined by enforcing radial equilibrium. For the first two models, the field problem is constituted by a system of two 2nd order differential equations into two variables, namely the displacement of the inner (or outer) layer of mortar and of the fiber textile. A 1D shooting is employed, after having converted the boundary value problem (BVP) into an initial value one (IVP), being the latter fully explicit. For the third model, the field problem is constituted by a system of three 2nd order differential equations, and an additional displacement variable is introduced, necessitating a 2D shooting. The validation is carried out through comparisons with existing experimental data. Good predictions of the load-slip curves, for different strengthening configurations (extrados and intrados with two curvature radii), are observed. In addition, an insight into local stress distributions and material degradation for matrix layers and interfaces is obtained.

Dynamic shear behavior of CFRP-concrete interface: Test and 3D mesoscale numerical simulation

The study on dynamic shear behavior of fiber reinforced polymer (FRP)-concrete interface is of great significance for the performance evaluation and design of FRP externally strengthened concrete structures. Firstly, the quasi-static and dynamic single shear test on the interfacial shear behavior between carbon fiber reinforced polymer (CFRP) sheet and concrete substrate was carried out. The corresponding failure modes of CFRP-concrete interface, CFRP strain-time histories, load-displacement curves, and interfacial shear stress-slip relationships under loading rates of 8.33 × 10−6–10 m·s−1 were obtained. It was indicated that the dynamic interfacial shear behaviors, i.e., interfacial failure mode, debonding load, interfacial shear stress, etc., were sensitive to loading rates. Then, a 3D mesoscale modeling approach of concrete with random shaped, sized, and spatially distributed convex polyhedron aggregates was proposed, in which the volume fraction of aggregates was adjustable within the range of 0–50 % through gravitational drop and size scaling of aggregates. Furthermore, based on the established 3D mesoscale concrete model and the zero-thickness cohesive elements for adhesive layer, numerical simulations for FPR-concrete interfacial shear behavior were conducted and validated by comparing with the present and existing quasit-static and dynamic single shear tests. The experimental phenomenon of the failure location transferring from concrete substrate to adhesive layer at high loading rates was numerically reproduced. Finally, the influences of strain rate enhancing effects of aggregates and mortar on the interfacial failure modes were discussed. It was revealed that the failure location transferring from the concrete substrate to the adhesive layer was significantly affected by the strength enhancement of mortar and aggregates with the loading rate increasing.

Discussion on ‘engineering properties of clay soil stabilised with glass powder and rubber particles – a comparative study’ [geomechanics and geoengineering (2023), 1–25, DOI: 10.1080/17486025.2023.2288927]

ABSTRACT We read with great interest the recent article by Anglaaere et al. (2023). In this article, clay soil with various contents of glass powder (GP) and tyre shred particles (TSP) were subjected to direct shear and California Bearing Ratio (CBR) test, and shear strength (τ) parameters and bearing capacity were reported, respectively. Furthermore, Anglaaere et al. (2023) have performed a correlation analysis and proposed a relationship between the CBR values and τ of the samples. The results presented by Anglaaere et al. (2023) might have been useful, but there are various issues associated with this article, which we want to bring to the attention of the authors, readers, and researchers. We further emphasise that this discussion article would eliminate the dissemination of errors in the scientific knowledge presented by Anglaaere et al. (2023), and will also open new perspectives to the readers and the research fraternity.

Bond Shear Tests to Evaluate Different CFRP Shear Strengthening Strategies for I-Shaped Concrete Cross-Sections.

I-shaped concrete girders are widely used in precast bridge and roof construction, making them a common structural component in existing infrastructure. Despite well-established strengthening techniques using various innovative materials, such as externally bonded carbon fibre reinforced polymer (CFRP) reinforcement, the shear strengthening of an I-shaped concrete girder is not straightforward. Several research studies have shown that externally bonded CFRP reinforcement might exhibit early debonding at the concave corners of the I-shape, resulting in a marginal increase in shear capacity. This research study aims to assess the performance of two different CFRP shear strengthening strategies for I-shaped concrete cross-sections. In the first strategy, CFRP was bonded along the I-shape of the cross-section with the provision of additional anchorage. In the second strategy, the I-shape was transformed into a rectangular shape by using in-fill blocks over which the CFRP was bonded in a U-configuration. In addition to the strengthening strategies, the investigated parameters included two different materials for the in-fill blocks (conventional and aerated concrete) and two different anchoring schemes (bolted steel plate anchor and CFRP spike anchor). To avoid testing on large-scale girders, a new test methodology has been implemented on concrete I-sections. The test results demonstrate the feasibility of comparing different shear strengthening configurations dedicated to I-sections. Among other findings, the results showed that the local transformation of the I-shape to an equivalent rectangular shape could be a viable solution, resulting in shear strength enhancement of 12% to 53% without and with the anchorages, respectively.

Dynamic mechanical behavior of CNT-reinforced epoxy under medium-strain rate: A comparative study

Carbon nanotubes (CNTs) are generally recognized as one of the most effective fillers to improve the properties of polymeric materials. Subjected to dynamic loading, polymer-based materials often exhibit high strain rate sensitivity. This research investigates the effectiveness of CNTs fillers on the mechanical properties of an epoxy resin at low to medium strain rates through conducting a comparative experimental study. Performing tensile and shear tests, the elastic modulus and strength properties of CNT/epoxy and pure epoxy resin are measured at different strain rates. By proposing an empirical logarithmic relationship, the prediction of dynamic elastic modulus and strength properties at any desired low to medium strain rate is facilitated. For measuring the dynamic fracture toughness of CNT/epoxy and pure epoxy resin at medium strain rate, the instrumented charpy impact test based on the Dynamic Key Curves (DKC) method is used. Experimental measurements still imply on significant enhancements in axial and shear properties and also dynamic fracture toughness up to medium strain rates of 150 s−1 by adding small portion of CNTs.

Deep learning-based prediction of particle breakage and friction angle of water-degradable geomaterials

Crushed soft rocks are becoming inevitable geotechnical materials for construction of foundations, fill material for transportation infrastructures, and earthen dams for economic and environmental reasons. The contemporary issue is to predict the water-induced disintegration of these non-traditional granular materials and its correlation with the friction angle of these soils. Machine learning techniques offer a viable solution in this context as they are widely used to understand and predict complex phenomena across various applications. In this work, a deep learning technique, artificial neural networks (ANN), was employed to an experimental dataset obtained from torsional shear tests on dry and saturated crushed soft rocks to predict the water-induced particle breakage potential (ID), peak friction angle (PFA), and residual friction angles (RFA). The experimental ID – PFA and ID – RFA correlations were also predicted using ANN model for all the three outputs (ID, PFA, RFA) with very low errors.

Modeling Interface Damage with Random Interface Strength on Asphalt Concrete Impervious Facings.

Asphalt concrete impervious facings, widely adopted as the impervious structures for rockfill dams and upper reservoirs in pumped storage power stations, typically have a multilayer structure with a thin sealing layer, a thick impervious layer, and a thick leveling bonding layer. The properties of the interfaces between these layers are crucial for the overall performance of the facings. This paper develops a model to investigate the complex interface damage behavior of the facing under static water pressure and gravity. The model considers two damage origins: one is the interface adhesion-decohesion damage, which is described by the cohesive zone model (CZM) combined with the Weibull-type random interface strength distribution, and the other is the bulk damage of each layer, described by Mazars' model. Primarily, a comparison between numerical simulation and indoor direct shear tests validates the reliability of the CZM for the asphalt concrete layer interface. Then, the damage distribution of the two interfaces is simulated, and the characteristics of the interface stress are analyzed in detail. The interface shear stresses of the ogee sections, which have different curvatures, all show an interesting oscillation between the thin sealing layer and the impervious layer, and the interface damage at this interface exhibits high heterogeneity. Furthermore, tension stress exists in the local zones of the ogee section, and the damage in this section is significantly greater than in other parts of the facings.

Enhanced mechanical and interfacial performances of carbon fiber reinforced composites with low percentage of amine functionalized graphene

AbstractThis paper reports improvement in the tensile, flexural and interlaminar shear strength (ILSS) properties of ADG‐NH2/Epoxy/CFRP composites at low filler content. Five symmetrical CFRP composite laminates were prepared through wet layup process assisted by vacuum bagging technique with varying wt% proportions (0.25, 0.5, 0.75 and 1) of ADG‐NH2/Epoxy. Tensile tests, short beam shear test and flexural tests were carried out as per ASTM D3039, ASTM D2344 and ASTM 790‐10 respectively to assess the effect of the ADG‐NH2 functionalized nano additives on their mechanical properties. The variation in ILSS were studied for varying temperatures (room temperature, 35, 50, 75, 85, & 100°C for each type of ADG‐NH2/Epoxy wt% (neat, 0.25, 0.5, 0.75 & 1)) of ADG‐NH2/Epoxy/CFRP composites. The ILSS was enhanced up to ∼27% for 0.5 wt% of ADG‐NH2 reinforced CFRP at room temperature but reduced with the higher concentrations (0.75 wt% & 1 wt%). It was observed that ILSS reduced with gradual temperature variations up to 100°C w.r.t room temperature. But an increment was observed up to 0.5 wt% for ADG‐NH2 for all temperature. Form the test results, it has been recorded an improvement in mechanical properties that is, the elastic modulus by ∼18%, ultimate tensile strength by ∼21%, % elongation at break by∼19% and toughness by∼28% for the 0.5 wt% of ADG‐NH2 graphene nano additive reinforced CFRP composite laminates as compared to neat epoxy CFRP laminates. Results also show the augmentation in the Max load by ∼24%, flexural strength by ∼33%, flexural modulus by ∼43%, and flexural strain by ∼26% were observed for the 0.5 wt% of ADG‐NH2 graphene nano additive reinforced CFRP composite laminates as compared to neat epoxy CFRP composite laminates. Fractographic studies of fractured surface using SEM analyses shows better adhesion mechanisms which supports the augmentation in mechanical properties with addition of amine functionalized graphene to CFRP laminate.Highlights Reinforcement of amine functionalized (ADG‐NH2) graphene in the epoxy matrix and incorporation with carbon fibers to enhance the interfacial and flexural properties. Evaluation of temperature effects on interlaminar shear strength properties of amine functionalized CFRP composites Improvements in tensile, ILSS and flexural properties observed for a low percentage (0.5 wt%) of ADG‐NH2 graphene reinforced CFRP composite laminates. Use of aerospace grade epoxy and resin with amine functionalized graphene for further use in aerospace industry applications.

Effect of Drained Multi-Directional Loads on Liquefaction Resistance of Granular Material

ABSTRACT It is well recognized that the liquefaction resistance is closely related to the consolidation stress in soils. However, previous studies investigated the effects of unidirectional consolidation loads rather than multi-directional consolidation loads on liquefaction resistance. In this study, two types of granular materials, spherical glass beads and irregularly-shaped sands, are tested under undrained conditions with the uni- and bi-directional loads to investigate the liquefaction resistance. The effects of consolidation loads on liquefaction resistance can be explained in terms of material anisotropy. In simple shear tests, the stress- and strain-controlled loading paths are adopted for the consolidation and the undrained shear process, respectively. The results indicate that the liquefaction resistances of both materials consolidated under the multi-directional consolidation loads are higher than those consolidated under the linear loads. More consolidation loading cycles induce a better liquefaction resistance of the specimens at a given relative density. In addition, the influence of consolidation stress on liquefaction resistance is demonstrated by the anisotropy of specimens. Cyclic vertical stress, unidirectional shear stress, and bidirectional shear stress applied during consolidation produce greater isotropy and improve the liquefaction resistance of the specimen compared with the monotonic vertical stress, and their effects align with an increasing order.

Physico-mechanical properties of halite and gypsum–mudstone crushed rock backfills of the Mercia Mudstone Group

Permanent disposal of radioactive waste in deep geological repositories (DGRs) relies on engineered barriers, such as crushed rock backfills, to ensure that wastes are isolated and contained. The performance of crushed rock backfill, during construction, operation and closure, relies on optimizing its mechanical properties. This paper explores how density and composition influence the strength of (i) crushed halite and (ii) crushed gypsum–mudstone mixtures of the Triassic Mercia Mudstone Group, which is a potential DGR host rock in the UK. Unconfined compressive strength (UCS) testing of compacted halite demonstrated that strength correlated with compaction density, with UCS increasing from 220 kPa at a density of 1.72 g cm −3 up to 6600 kPa at the maximum achieved density of 1.83 g cm −3 . Direct shear testing revealed an angle of internal friction for crushed halite samples of 39°–40° at a density of 1.5 g cm −3 . Direct shear testing of gypsum–mudstone composites from 100% gypsum to 100% mudstone revealed that higher gypsum percentages provide greater frictional shearing resistance, whilst higher mudstone percentages promote more cohesive strength. Data are also presented on bulk materials characterization by X-ray fluorescence (XRF), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS) and optical microscopy. This research provides insights into how the strength properties of compacted crushed halite and gypsiferous mudstone backfills can be engineered through control of density and composition.

Influence of Laminate Twist and Clamping Pressure on Bonding Performance of Low-Grade Lumber in Cross-Laminated Timber

Abstract The geometric variations of low-grade lumber raise concerns about bond strength of cross-laminated timber (CLT) produced from such lumber. This study seeks to investigate the effect of low clamping pressure and geometric variations of laminates on the bond strength of CLT. CLT panels were manufactured from low-grade grand fir (Abies grandis). Block shear tests and cyclic delamination tests were conducted on specimens randomly taken at specific points that correspond to a wide range of twist magnitude. Twist distribution in the lumber used as laminates in the CLT ranges from 0 to 160 mm. Results showed that twist magnitude and clamping pressure have significant effect on bond performance, with twist magnitude having an overriding effect on pressure.

Behavior of Different Ultrasonically Bonded Aluminum Heavy Wires in the Shear Test

Shear tests are known to be quick tests for heavy wire bonds to evaluate the interconnect quality. The challenge is to interpret the results of such shear tests, in terms of shear strength and the shear code defined by the German Welding Society (DVS). In this study, we aim to get a better understanding of the shear process by studying the material behavior through the shear test of heavy wire bonds. We took two different aluminum wire materials, Al H11 and AlMg0.5, and ultrasonic bonded them on 99.95% copper sheets, resulting in a good bond quality according to the DVS standard. We performed shear tests on these samples, stopping them shortly before final failure. We investigated the resulting deformed state by cross-sections and further instrumental indentation patterns in the middle of the wedge. The indentation hardness patterns revealed that Al H11 and AlMg0.5 behave significantly differently in terms of hardening under deformation. Our experiments show that the different material behavior has an influence on the failure path of the shear tests. We conclude, when comparing different materials by means of shear test results, that the outcome is influenced by the different hardening behavior.

Research on the adhesion mechanism and compatibility of acrylate composite polyurethane binder − aggregate based on surface free energy theory

The raw materials selection and design of waterproof polymer concrete for steel bridge deck paving lack clarity regarding the adhesion mechanism and optimal compatibility between acrylate composite polyurethane binder (APUB) and various aggregates. This study systematically investigates these issues based on surface free energy (SFE) theory. Initially, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques are utilized to characterize chemical structure of APUB. Subsequently, obtaining the SFE parameters of APUB and aggregates through contact angle tests, and establishing the evaluation indices compatibility ratios ERs (ER1 and ER2) for the most compatible APUB-aggregate pairs. Finally, the correlation between ERs and the water stability of the APUB-aggregate pair is verified through shear tests conducted on sandwich specimens immersed in water. The findings reveal that APUB exhibits both acidic and non-polar surface properties. The SFE values of all aggregates surpasses that of APUB, indicating APUB's ability to wet the surfaces of all aggregates. Under dry conditions, non-polar basalt and limestone aggregates exhibit strong adhesion to APUB. This is primarily due to the combined effects of acid-base chemical reactions and the principle of compatibility, with the former predominating. Under wet conditions, APUB on non-polar basalt and limestone surfaces exhibits reduced susceptibility to displacement and detachment by water. The closer the polarity component of polar aggregates is to that of water, the easier water can displace APUB from the polar aggregate surfaces. Correlation analysis between the maximum shear force of the immersed specimens and the ER2 indicates that the APUB-basalt pair has the best compatibility. The cohesive work of APUB is crucial in establishing compatibility indicators for evaluating APUB-aggregate pairs. This study provides a theoretical basis for the raw material selection and design of polymer concrete for steel bridge deck paving.

Microstructure modification and mechanical reinforcement in sub-10 μm scale Cu/Sn–Ag/Cu microbump joints via Co-addition of Zn and Ni in Cu substrates

The trend towards miniaturization of solder joints addresses the need for high-density interconnections in microelectronics. Excessive intermetallic compounds (IMC) and phase transformations cause internal stresses, leading to voiding and cracking in conventional microbumps. Therefore, advanced microbump design must focus on IMC suppression and phase stabilization. This study explores Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps, comparing them to conventional Cu/Sn-3.5Ag/Cu under various reflow times. High-field emission electron probe micro-analysis and transmission electron microscopy reveal improved microstructures. Electron backscatter diffraction confirms the (Cu,Ni)6(Sn,Zn)5 grain size of several hundreds of nanometers. Fracture modes were established based on the correlation between shear testing and fracture surfaces. Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps enhanced shear strength (19.6 %–97.8 %) and failure toughness (10.6 %–132.1 %) compared to Cu/Sn-3.5Ag/Cu. The solid solution strengthened and refined (Cu,Ni)6(Sn,Zn)5 combined with tough bulk (Cu,Ag)5(Sn,Zn)8 in Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps, demonstrate a tough microstructure. These findings provide insights into the design of microbumps with a bonding height in sub-10micron scales.