Decrease In Shear Strength Research Articles

Experimental and Numerical Study on Nonlinear Shear Behavior and Constitutive Model of Deep Shale Laminae Planes

The direct shear tests showed that the degradation of unevenness and waviness of the laminae plane is the primary reason for the dynamic decrease in shear strength. A shear constitutive model was proposed which considers the scale effect and the asperity geometry of the unevenness and waviness of the laminar plane. The evolution of the shear strength and stiffness with a normal stress and scale effect during the shearing of shale laminae planes was explored. The results show that high normal stress aggravates the stiffness hardening of laminae planes and forms larger peak shear stress and peak shear displacement. At the lab scale, the increase in the unevenness wavelength has a hardening effect on the shear stiffness and strength. The small-scale unevenness contributes most to the shear strength of shale laminae planes at the lab scale. At the field scale, the increase in the waviness wavelength has a softening effect on the shear stiffness and strength.

Achieving metallurgical bonding in steel faceplate/aluminum foam sandwich via hot pressing and foaming processes: interfacial microstructure evolution and tensile behavior

This study introduces an innovative approach to fabricating aluminum foam sandwich with aluminized steel faceplates through metallurgical bonding. The process involves the use of foamable precursor, prepared via melt stirring, and subsequent hot pressing and foaming, offering a cost-effective and industrially feasible method for producing lightweight structural materials and connection of steel/aluminum dissimilar metals. This study focuses on exploring the changes in the microstructure of the bonding interface before and after foaming, and revealing the impact of these changes on the tensile results. Foaming experiment shows that foamable sandwiches have superior foaming ability, and the core layer density after foaming is between 0.283 and 0.591 g/cm ³. Microstructural characterization results demonstrate that, during the hot pressing process, fine equiaxed grains are observed on the iron side of the interface, indicating dynamic recrystallization occurred. The formation of a small amount of η-Al5Fe2 at the interface is a primary factor causing the deflection of the fracture path. Subsequently, during the foaming process, intermetallic compounds (IMCs) θ-Al13Fe4, τ5-Al7Fe2Si, and β-Al4.5FeSi formed sequentially, mainly determined by the diffusion reaction of silicon elements. The formation of these IMCs led to an increase in microhardness at the interface and a decrease in shear strength. Digital image correlation was utilized to examine strain distribution under tensile loading. The result indicates that the damage accumulation is characterized by the formation and expansion of strain bands, with failure manifested as the interconnection of these strain bands.

INVESTIGATION OF THE SHEAR STRENGTH OF REINFORCED SILTY SAND

Introduction: This paper presents an experimental investigation that aims to study the influence of silt content, glass fiber content, and their combined effect on the shear behavior of silty sand. For this purpose, a series of tests using direct shear apparatus (as methods) were carried out on sand mixed with various silt and fiber contents. Samples were prepared with a relative density of 50 %, and each mixture was tested at three different normal stresses. The experimental results indicated an increase in shear strength at 10 % silt content, followed by a decrease in shear strength with increasing silt content from 10 % to 30 %. It was also found that 0.5 % is the optimal content that can be added to sand-silt mixtures to enhance their shear strength and friction angle, although the mixtures become more contractive.

Experimental study on shear mechanical properties of concrete joints under different unloading stress paths

In order to study the shear mechanical properties of rock joint under different unloading stress paths, the RDS-200 rock joint shear test system was used to carry out direct shear tests on concrete joint specimens with five different morphologies under the CNL path and different unloading stress paths. The unloading stress paths include unloading normal load and maintaining constant shear load (UNLCSL), unloading normal load and unloading shear load (UNLUSL), unloading normal load and increasing shear load (UNLISL). The results show that the peak shear strength, cohesion, internal friction angle, pre-peak shear stiffness and residual shear strength of concrete joints under CNL path increases with the increasing JRC and normal stress. Under the UNLCSL path, under the same initial shear stress τ1, instability normal stress σi decreases with the increasing JRC, and normal stress unloading amount Δσn increases with the increasing JRC. Under the same JRC, σi increases with the increase of τ1, and Δσn decreases with the increasing τ1. Under the same JRC and σi, τi is significantly smaller under the UNLCSL path than the CNL path. Under the same JRC, the cohesion under the UNLCSL path is less than the CNL path, and the internal friction angle is higher than that the CNL path. Under the same JRC and σi, τi is the largest under the path of CNL and UNLISL, followed by the UNLCSL path, and τi under the UNLUSL path is the smallest. Compared with the CNL path, the variation range of the specimen internal friction angle is within 3% while the average decrease percentage of the specimen cohesion reaches 37.6% under the UNLCSL path, UNLISL, and UNLUSL. Therefore, it can be inferred that the decrease in cohesion caused by normal unloading is the main reason for the decrease in joint instability shear strength. After introducing the correction coefficient k of cohesion to modify the Mohr-Coulomb criterion, the maximum average relative error after correction is only 3.5%, which is significantly improved compared with the maximum average relative error of 56.9% before correction. The research conclusions can provide some reference for the accurate estimation of shear bearing capacity of rock joints under different unloading stress paths, which is of great significance to the stability evaluation and disaster prevention of rock mass engineering.

High-reliability Sn37Pb/Sn58Bi composite solder joints by solid-liquid low-temperature soldering

As the feature sizes of integrated circuits approach their physical limits, 3D packaging has emerged as a crucial technology for enhancing integration and extending Moore's Law. To meet the future requirements for low-temperature solder and interconnect processes in aerospace 3D packaging, this study combined Sn37Pb solder balls with Sn58Bi solder paste to prepare uniform composite solder joints under reflow conditions of 180°C for 10 minutes (CS-180–10) and 190°C for 1 minute (CS-190–1). The Bi atoms dissolved in the Pb phase strengthened the composite solder and made the crystal structure more ordered and predictable. The composite solder joints formed under both process conditions exhibited shear strengths higher than those of Sn37Pb solder joints prepared at 220°C for 1 minute, both before and after aging at 100°C. The fracture mode of the composite solder joints transitioned from ductile to mixed ductile-brittle with aging. Additionally, the composite solder demonstrated better creep resistance than SnPb solder at all tested strain rates in nanoindentation tests. Compared to CS-180–10, the lower heat input CS-190–1 featured finer Pb phases and Pb grains, better wettability, and better thermal stability. CS-190–1 showed only a 5.9 % decrease in shear strength after 42 days of aging at 100°C. This study offers a new solution for low-temperature, high-reliability interconnections in future aerospace integrated circuit 3D packaging.

The microstructural evolution of material extrusion based additive manufacturing of polyetheretherketone under different printing conditions and application in a spinal implant

AbstractWith the advances in additive manufacturing, polyetheretherketone (PEEK), a biocompatible polymer, can be used in biomedical applications such as spinal implants. This paper aims to investigate the evolution of the microstructure of PEEK parts manufactured by material extrusion (MEX)‐based additive manufacturing with different printing parameters. The effect of layer thickness (LT) and nozzle diameter on mechanical properties was investigated using tensile, Charpy impact, and short beam strength (SBS) tests. Two different LTs, 0.1 and 0.2 mm, and two different nozzle diameters, 0.6 and 0.8 mm, were used as printing parameters. By increasing the LT, tensile strength dropped by around 24%, and impact strength by almost 55%. Moreover, altering the LT resulted in a 15% decrease in interlaminar shear strength (ILSS) from the SBS test. In addition, increasing the nozzle diameter also led to a significant reduction in all of the results as tensile strength, Charpy impact strength, and ILSS. The results were also consolidated by scanning electron microscopy. The main findings were that increasing LT leads to an increase in microstructural defects that act as stress concentrators. Following the tests, response surface methodology (RSM) was used to determine optimal printing parameters. In the end, using the optimum printing parameters from the RSM study, a structural analysis of a MEX‐printed spinal implant was conducted through finite element method, considering the loading cases mimicking daily human body motions.Highlights As layer thickness increased, tensile and impact strength dropped. Tensile and impact strength dropped truly with increasing nozzle diameter. SEM revealed that increasing layer thickness causes more microstructural flaws. FEM analysis showed that PEEK‐based implant provides structural integrity.

Deterioration of a compacted soil due to suction loss and desiccation cracking

This paper presents the results of laboratory testing of a clayey soil taken from a road subgrade in Tanzania. The results revealed a reduction in the soil water retention capacity, accompanied by shifts in the water retention curves with successive cycles. These changes affected the soil response to shear loading, resulting in decreased shear strength and stiffness with hydraulic cycles. While the soil experienced suction losses due to desiccation cracks and hysteresis effects, these suction variations alone could not account for the observed changes in shear strength, implying that the development of desiccation cracks contributed to reduced strength and stiffness. The results showed that the degradation effect of crack development on the shear strength and elastic modulus of the soil during hydraulic cycles could be justified using a macroscopic degree of saturation, i.e. the degree of saturation of large pores external to the aggregates, through a microstructural-based effective stress approach. This allowed the increase in the large pores resulting from crack development to be accounted for and hence the successive reductions in shear strength and stiffness with drying-wetting cycles. These deterioration effects need to be considered for design of geotechnical infrastructure to ensure stability, and resilience of infrastructure over time.

Molecular dynamics study on the temperature effect on shear failure of epoxy adhesive

This study aims to investigate the shear behavior of epoxy resin adhesives at different temperatures, and to reveal the shear mechanism through experimental tests and molecular dynamics(MD) simulations. The shear strength at different temperatures was experimentally tested. With the increase of temperature, the shear strength decreases obviously. Then, the three-layer shear model was constructed based on the experimental process, and shear simulations were conducted at the corresponding temperatures. The simulations reveal that with increasing temperature, the adhesive exhibit more intense thermal motion, leading to a decrease in cohesive energy density. Additionally, as the temperature rises, the energy of the system increases, rendering it more unstable and resulting in a decrease in shear strength. This study provides valuable insights into the temperature effects on the shear process of epoxy resin adhesives.

Brazing of Porous Nickel to Copper and Stainless Steel: Microstructure and Mechanical Properties

A porous nickel (Ni) was brazed to copper (Cu) and stainless steel 304 (SS304) using VZ2250 and MBF67 brazing filler metal with a composition of 77.4Cu-9.3Sn-7.0Ni-6.3P and 64.5Ni-25Cr-6P-1.5Si (Cu: Copper, Sn: Tin, Ni: Nickel, P: Phosphorus, Cr: Chromium, Si: Silicon), respectively for joint microstructure and mechanical properties analysis. Porous Ni with a pore density of 15 pores per inch (PPI) was sandwiched between Cu/VZ2250 and MBF67/SS304. A brazed joint of Cu/Porous Ni/SS304 with VZ2250 and MBF67 brazing filler metal was prepared in a high vacuum furnace at different brazing times of 5, 10, and 15 minutes for 1015 °C with a heating and cooling rate of 10 °C/min, respectively for comparison purpose. The microstructure and mechanical properties of the brazed joint were investigated to identify the joint ability after the brazing process. Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS) confirmed the interfacial microstructure by the formation of the diffusion filler metal (dark grey colour) for the Cu/Porous Ni/SS304 with VZ2250 and MBF67 brazing filler metal. For shear strength tests, the value decreases with an increase in the brazing time. The shear strength tests for the brazed joint of Cu/Porous Ni/SS304 with VZ2250 and MBF67 brazing filler metal show the maximum shear strength test value can be achieved for the brazing time of 5 minutes. The decreasing shear strength value was observed with differences in structural data of porous Ni due to the softening after the brazing process. Keywords: Brazing, Microstructure, Porous Nickel, Shear Strength.

Stable SnAgCu solder joints reinforced by nickel-coated carbon fiber for electronic packaging

Today’s 3D electronic packaging is characterized by smaller size and higher functional density, which generally require multiple reflow cycles. However, due to the Ostwald ripening process of the interfacial intermetallic compound (IMC), the solder joint’s strength would decrease as the number of reflow cycles increases. To address this, we developed a novel composite solder by incorporating nickel-coated carbon fiber (Ni@CF) into the Sn–3.0Ag–0.5Cu (SAC305) solder connection. The study showed that Ni@CF effectively enhanced the stability and reliability of solder joints during multiple reflow processes. Compared with Ni@CF-free equivalents, Ni@CFs promoted the nucleation of interfacial IMC during the solid–liquid reaction and inhibited Ostwald ripening, leading to a refinement of the interfacial IMC grains. As a result, the interface was strengthened, and the shift of shear fracture to the brittle interface seen in the SAC305 solder joint with multiple reflows did not occur in the composite solder joint. Furthermore, carbon fiber strengthened the solder matrix through the load transfer and shear-off mechanisms, depending on its inclination angle with the shear plane. Consequently, the Ni@CFs-reinforced solder joints maintained a shear strength of over 42 MPa throughout ten reflow cycles, while the pristine SAC305 solder joint exhibited decreased shear strength to 33 MPa. This study provides new insights into composite solder joints’ stability and reinforcement characteristics when subjected to multiple reflows.

Numerical analysis of downward progressive landslides in long natural slopes with sensitive clay

Landslides occurring in sensitive clay often result in widespread destruction, posing a significant risk to human lives and property due to the substantial decrease in undrained shear strength during deformation. Assessing the consequences of these landslides is challenging and necessitates robust numerical methods to comprehensively investigate their failure mechanisms. While studies have extensively explored upward progressive landslides in sensitive clays, understanding downward progressive cases remains limited. In this study, we utilised the nodal integration-based particle finite element method (N-PFEM) with a nonlinear strain-softening model to analyse downward progressive landslides in sensitive clay on elongated slopes, induced by surcharge loads near the crest. We focused on elucidating the underlying failure mechanisms and evaluating the effects of different soil parameters and strain-softening characteristics. The simulation results revealed the typical pattern for downward landslides, which typically start with a localised failure in proximity to the surcharge loads, followed by a combination of different types of failure mechanisms, including single flow slides, translational progressive landslides, progressive flow slides, and spread failures. Additionally, inclined shear bands occur within spread failures, often adopting distinctive ploughing patterns characterised by triangular shapes. The sensitive clay thickness at the base, the clay strength gradient, the sensitivity, and the softening rate significantly influence the failure mechanisms and the extent of diffused displacement. Remarkably, some of these effects mirror those observed in upward progressive landslides, underscoring the interconnectedness of these phenomena. This study contributes valuable insights into the complex dynamics of sensitive clay landslides, shedding light on the intricate interplay of factors governing their behaviour and progression.

Recent advances in stability analysis and design of 3D slopes

Slope failures in nature and engineering are typically three-dimensional (3D). The rotational failure mechanism derived from the variational limit equilibrium (LE) method shows superior performance in the stability analysis of the 3D slope. In contrast to the traditional LE methods, it avoids arbitrary kinematical and statical assumptions. Stability charts obtained by the variational LE method are used to derive explicit expression equations of the safety factor, also known as the stability equations, for both 3D reinforced and unreinforced slopes. These equations are highly accurate and can provide a convenient means to assess slope stability in practical engineering. An example of a convex reinforced slope with a turning arc is illustrated in this study to investigate the effect of the 3D effects on the required reinforcement length for design. The results indicate that the 2D method underestimates the required reinforcement length when dealing with a 3D reinforced slope problem. Furthermore, a forensic analysis of the Yeager Airport reinforced slope is conducted within the framework of the variational LE method. The required strength for stability is found to be significantly less than the allowable strength of reinforcements without considering the decrease in soil shear strength. However, the required strength greatly exceeds the allowable strength when the decrease in soil shear strength is considered. The results verify that the decrease in shear strength of the weak layer is responsible for the collapse.

Counter-intuitive mechanical performance variation in aged low-temperature interconnections in electronic packaging

Different from the conventional aging induced continuous mechanical performance deterioration in solder joints, a counter-intuitive “decrease-increase-decrease” variation in shear strength with a peak value 12 MPa higher than the initial state was captured in aged low-temperature BGA structure Cu/Sn–58Bi/Cu solder joints. The first decrease in shear strength was dominated by the coarsening of Sn and Bi phases. The following increase in shear strength was rooted in the concurrent Bi subgrain strengthening, solid solution strengthening of Bi element in Sn-rich phase and precipitation strengthening induced by the Bi-rich phase particles. The eventual decrease in shear strength was ascribed to severely deteriorated interface between the solder matrix and intermetallic compound layer being the weaker site in the long time aged solder joint. This aging induced strengthening phenomenon is inspiring in mechanical performance optimization and reliability elevation of SnBi-based solder joints for the coming chiplet and heterogeneous integration packaging.

Study on the Shear and Bending Mechanical Properties of Millet Stem

To determine the patterns and influencing factors of the mechanical properties of millet stems from different varieties during the maturity period, this study employed a complete block experiment method and conducted shearing and bending tests on millet stems using the INSTRON5544 electronic universal material testing machine. The research investigated the variation in the shear strength, specific shear energy, bending strength, elastic modulus, and bending stiffness at different internode positions of the stems of Changza 466, Zhangza 16, and Jingu 21 during their maturity period. The results indicated that the variety had a significant impact on the mechanical properties of millet stems: from largest to smallest, the order of shear and bending forces was Jingu 21, Zhangza 16, and Changza 466. The shear strength and bending strength of Jingu 21 were the greatest among the three stem samples. The internode position significantly affected the shear mechanical properties of the millet stems, showing a general trend of decreasing shear strength with ascending internode position. The effect of the internode position on the bending stiffness was highly significant, whereas its impact on the bending strength and elastic modulus was not significant. The shear strength of the millet stems ranged from 3.866 ± 1.086 to 6.953 ± 2.208 MPa, significantly lower than the bending strength, which ranged from 18.934 ± 4.374 to 34.286 ± 6.875 MPa. The lowest shear strength and specific shearing energy, recorded at the fifth internode, were 4.028 ± 1.918 MPa and 15.097 ± 12.633 MJ/mm2, respectively. Jingu 21 and Changza 466 exhibit better lodging resistance than Zhangza 16. It is recommended to use a cutting-type platform for harvesting millet stems, with the cutting height set at the fifth internode position. This study provides a theoretical basis for the design of millet harvesting machinery and the selection of harvest parameters.

Stress stress-strain behavior of hydraulic filled coral sand subjected to internal erosion

Coral sand foundations lose fine particles under the action of groundwater infiltration. As the soil skeleton structure deteriorates, the foundation becomes uneven and may even collapse. In this study, a triaxial drainage shear test of coral sand is used as a quantitative control method for the loss of fine particulate soil, and the effect of internal erosion on the mechanical behavior of coral sand is evaluated. An experiment is used to demonstrate that erosion leads to a decrease in the peak shear strength and residual strength of coral sand. Erosion has different effects on coral sand with different fine particle contents, and the effects on the friction angles of coral and terrestrial sand are also different. The secant modulus E50 and peak secant modulus Ep gradually decrease as the loss of fine particles increases. The effect of fine particle loss on the peak secant modulus Ep is significant at fine-particle losses exceeding 10% for a fine-particle content of 20%. The loss of fine particles creates new pore spaces in the coral sand, which, in turn, affects the stability of the original soil skeleton. Erosion has been shown to have an effect on the gradational features of coral sand, leading to the phenomenon that the dilatancy effect increases as a function of the amount of erosion that takes place. To prevent uneven foundation settlement caused by subsurface erosion in engineering designs, it is important to consider the gradation characteristics and fine particulate content of coral sand, which affect the stability of coral reef foundations.

Analysis of the Influence of Groundwater Level on Slope Stability at Highwall PT. X, South Kalimantan

Mine slope design is an important part of mining operations because it is used to determine the balance between mine economy and operational safety. In the mine slope design there will also be a groundwater level design, the groundwater level is one of the triggers for a slide to occur. Therefore, this study aims to determine the effect of the groundwater level on the stability of the highwall slope cross section A-A’ as well as to determine the factor of safety value and probability of slope failure under various conditions of high groundwater levels. This research method uses quantitative methods because there are numerical data that will be used to calculate the value of slope stability. Slope stability analysis uses the “morgenstern-price” boundary equilibrium and the “monte-carlo” landslide probability. From the research results it is known that the higher the groundwater level, the lower the safety factor value because the presence of groundwater can reduce slope stability causing a decrease in soil shear strength due to increased pore water pressure. In addition, the weight of the material will increase due to the presence of groundwater, which causes the driving force on the slope to also increase. In addition, the movement of air in the soil can cause seepage forces which can affect slope stability. The lowest safety factor value is at the groundwater level 100% of the overall slope height, in conditions of 100% of the overall slope height, the deterministic safety factor value is 1.337, the mean safety factor is 1.358, and 0% hazard susceptibility.

Triggering and evolution of static liquefaction in submarine slopes with quasi-saturated sand

Liquefaction flow slides of submarine slopes with quasi-saturated sand have been frequently observed in engineering practice. That instability can be attributed to a decrease in resistant shear strength caused by static liquefaction. However, the triggering of static liquefaction in submarine slopes has received limited attention. To address this gap, a state-dependent constitutive model for quasi-saturated sand with entrapped air is employed that can represent the effects of compression and dissolution of gas accurately. Moreover, the soil model enables the evaluation of the triggering of static liquefaction based on second-order work. To study the triggering mechanism of static liquefaction, a submarine slope model is established using the material point method. The static liquefaction area is detected by the vanish of second-order work. Results indicate that static liquefaction initially arises at the slope surface and gradually expands towards the interior of the slope as the rapid loading at the top of the slope increases. Furthermore, the presence of entrapped gas within the slope can effectively enhance the resistance to slope instability caused by static liquefaction. It significantly alters both the location where static liquefaction is initially triggered and the subsequent evolution pattern, in comparison with saturated submarine slopes.

Silicon regulation of the interface microstructure and shear strength of rheological cast-rolling aluminum/steel composite plates

This study reports the preparation of medium-thickness aluminum/steel composite plates with different diffusion layers using rheological cast-rolling technology. The thermodynamic software and first-principles were employed to determine the effects of different silicon contents on the solidification process and mechanical properties of the 6061 aluminum/steel composite plates. The research revealed that the Fe2Al5 phase on the steel side possessed a tongue-like preferential growth at a silicon content of less than 1.2 wt%. A granular Al–Fe–Si phase was formed on the aluminum side of the diffusion layer when the silicon content exceeded the saturation solubility (1.8 wt%), which completely suppressed the tongue-like preferential growth of the Fe2Al5 phase. First-principles calculations revealed that the matrixes showed superior toughness in comparison to binary intermetallic compounds (IMCs), while the toughness of binary IMCs surpassed that of ternary IMCs. The mechanical properties showed that the shear strength of the sample prepared by rheological cast-rolling was higher than that of composite casting and close to that of composite rolling, reaching a maximum value of 73.4 MPa. The shear strength initially increased and then decreased with an increase in isothermal diffusion time, and the fracture location was transferred from the loose FeAl3 to the Fe2Al5 phase. An increase in silicon content resulted in a slight increase in the microhardness of the diffusion layer, a delay of the peak value of the shear strength, and a reduction in the gradient of the shear strength. A substantial decrease in peak shear strength was observed when the silicon content reached 1.8 wt%.

Study on large scale direct shear test on soil-rock mixture with multiple grain grades in high fill slope engineering

Soil-rock mixtures are multiphase natural geological materials composed of mineral particles of multiple grain sizes, and have significant natural characteristics of multiscale material groups. In order to investigate the shear strength characteristics and deformation failure characteristics of soil-rock mixtures with multiple grain sizes under in-situ conditions in fill engineering, samples of soil-rock mixtures with multiple grain sizes under in-situ conditions were prepared, and large-scale in-situ direct shear tests were conducted under natural and water-soaked conditions. The test results showed that the shear strength of soil-rock mixtures is relatively high, and after saturated by water immersion, its shear strength decreases significantly, mainly manifested in the decrease of internal friction angle while the cohesion remains basically unchanged. The cohesion of soil-rock mixtures with multiple grain sizes is mainly provided by the shear-breaking cohesion of coarse particles such as gravel in the soil-rock mixture, and its degree of exertion is controlled by the grading characteristics and particle morphology of the soil-rock mixture and affected by constraints. The reason for the significant decrease in shear strength of soil-rock mixtures with multiple grain sizes after water-soaked saturation can be explained as follows: the clay film covering the surface of coarse particles becomes soft after water immersion, resulting in a significant decrease in the sliding friction resistance between coarse particles and the clay film, as well as the occlusion friction resistance generated by the rotation transfer between coarse particles through the clay film interface.

Influence of microvascular structured void content on composites subjected to in-plane shear loads

Microvascular fiber reinforced composites can be used as multifunctional structures capable of self-healing, thermal regulation, and communication, among others. The inclusion of a small volume of microchannels generally has a minimal impact on the mechanical properties of the composites. In the current work, the in-plane shear properties of microvascular composites containing embedded stainless steel and wall-less microchannels produced through sacrificial material removal were characterized for the first time. Microvascular unidirectional composites were manufactured with precisely located microchannels both aligned with and transverse to the fiber direction, and their in-plane shear properties were tested. Microchannels aligned with the fiber direction were shown to cause a substantial (−7%) decrease in shear strength but had no effect on shear modulus or failure strain. Distortion of the laminate surface around the channels oriented transverse to the fiber axis was observed, resulting in an increase in void content (1–4%), a 9% loss in shear modulus, and a 27% loss in shear strength. The use of a caul plate made the loss in shear strength statistically insignificant, increased the shear modulus by 12–15%, and decreased the shear strain by −25% relative to the baseline composite without microchannels. Digital image correlation showed that the surface strains for transversely oriented samples were interrupted near the microchannels, but post-test x-ray computed tomography and optical microscopy do not show crack redirection. The newfound understanding of the shear response of microvascular composites provides important insights that will enable future engineering designs of multifunctional aerospace structures.