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In this study, we investigated the mechanical and tribological properties of the layer-by-layer structure of additively manufactured implant-grade Polyether Ether Ketone (PEEK) through the Material Extrusion (ME) process as a potential substitute for artificial joints. The effective elasticity modulus of the anisotropic 3D-printed PEEK was determined to be 2.505 GPa along the vertical and horizontal build orientations. The lubricated friction and wear performance were assessed using a pin-on-disk test under various loads, including 14, 30, 50, and 70 N, with a sliding speed of 50 mm/s over a total distance of 1 km at 37 °C. The contact parameters between the hemispherical steel pin and 3D-printed PEEK disks, involving contact pressures over the circle of contact, were observed to increase as the load increased. The results indicated that the wear coefficient exhibited a rise from 1.418   ×   10 − 5 to 2.089   ×   10 − 1   as the applied loads increased, signaling a shift from mild to severe wear regimes. Fetal Bovine Serum (FBS) as a lubricant exhibited a mixed mechanism, ascertained through the Stribeck curve, as well as a minimum fluid film thickness of 1.346 nm under an isoviscous–elastic regime, as calculated by the maximum load. Moreover, the mechanism governing wear during sliding, influenced by both normal axial and shear loads, primarily involved adhesion. [ABSTRACT FROM AUTHOR]

In this work, the mechanical properties of the laser powder bed fused Hastelloy X alloy was studied by means of tension tests along and perpendicular to the building direction. The results showed that the as-built materials exhibited a fiber component with a maximum texture strength of ∼2.4. Meanwhile, the alloy showed a quite strong mechanical anisotropy such that the flow strength perpendicular to building direction was much higher than that along building direction by ∼100 MPa. By using the viscous-plasticity self-consistent (VPSC) method, it was demonstrated that such a large stress deviation cannot be ascribed to the weak texture. Meanwhile, considering the large aspect ratio of the columnar grains, a modified VPSC model was developed by taken the so-called phenomenological Hall-Petch relation into account, which was capable of accurately capturing the strong mechanical anisotropy of the present alloy. The modified VPSC model, which was calibrated to both the mechanical data and texture evolution during tension tests, was applied for virtual material testing along various tensile directions within the anisotropy plane of the material, whereby the advanced yield function Yld2004-18p was calibrated through the genetic algorithm. It was found that the Yld2004-18p yield function can accurately describe both the strength anisotropy and flow anisotropy of the material, whereby the initial and subsequent yield surfaces were generated for the LPBF Hastelloy X alloy.

In this study, the impact of asymmetric cross-rolling on the microstructure, crystallographic texture, and tensile anisotropy of a low-carbon steel sheet was evaluated. In the microstructures of the cross-rolled sheets, elongated α grains appeared in TD–ND and RD–ND sections, while equiaxed and irregular grains were seen in the RD–TD plane of the sheets. The results indicated that the asymmetric cross-rolling weakens the texture and γ-fiber due to the change in the path of strain during the deformation. The high increasing rate of hardness from 50 to 75% thickness reduction was related to the elimination of ⟨100⟩∥ND (with a low elastic modulus (129 GPa)) in the 75% cross-rolled sheet. Compared with the as-received sheet, the average yield and tensile strengths after 75% cross-rolling were increased to 620.9 and 705.6 MPa, respectively, due to strain hardening. As the cross-rolling strain increased, the rate of increase in strength decreased. For all samples (except 75% cross-rolled sheet), the maximum yield and tensile strengths were obtained along transverse direction owing to the presence of strong 〈111〉∥TD and 〈110〉∥TD texture. The anisotropy results indicated that large-strain asymmetric cross-rolling decreased the mechanical anisotropy degree of low-carbon steel. With an increase in imposed strain to 50% and 75%, the fracture gradually changed from fully ductile to a combination of fully ductile and shear ductile types. The presence of uniform dimples in the 0°-loaded and 45°-loaded sheets for 25% and 50% cross-rolled samples demonstrated the comparable rate of nucleation and growth of microvoids, which led to similar behavior of stress–strain curves after the necking for these sheets. [ABSTRACT FROM AUTHOR]

Palladium (Pd) and its alloys, renowned for their good corrosion resistance, catalytic efficiency, and hydrogen affinity, find extensive use in various industrial applications. However, the susceptibility of pure Pd to hydrogen embrittlement necessitates alloying strategies such as Pd-Ag systems. This study investigates the impact of the ordering on the phase stability and elastic properties of Pd-Ag alloys through first-principles calculations. We explore a series of ordered phase structures alongside random solid solutions using Special Quasirandom Structures (SQSs), evaluating their thermodynamic stability and elastic properties. Our findings indicate the possible existence of stable ordered L12 Pd3Ag and PdAg3 and L11 PdAg phases, which are thought to exist only in Cu-Pt alloys. An analysis of the elastic constants and anisotropy indices underscores some pronounced directional dependencies in the mechanical responses between the random solid-solution and ordered phases. This suggests that the ordered phases not only are thermodynamically and mechanically more stable than solid-solution phases, but also display a decrease in anisotropy indices. The results provide a deeper understanding of the atomic behavior of Pd-Ag alloys, and shed light on the design of multiphase Pd-Ag alloys to improve their mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, the effect of cryo-deformation and post-deformation annealing process on tensile, anisotropic and fracture behaviour of AA2099 has been investigated. The development of ultrafine-grained (UFG) microstructure is achieved initially by cryorolling (CR) process on the solution-treated (ST) alloy by subjecting it to a true strain value of 2.3. Cryorolled samples are then followed by annealing process at temperatures of 150°C (CR + 150°C) and 200°C (CR + 200°C). A notable improvement in yield strength (~342 MPa), ultimate tensile strength (~472 MPa), hardness (~138 HV) and fracture toughness parameters (KQ (31.8 MPa $$\surd m$$ √ m), Kee (31 MPa $$\surd m$$ √ m) and J integral (57.67 kJ/m2)) is recorded, whereas anisotropy increases in the rolling direction and ductility show a significant drop at CR sample condition in comparison with coarse grains at ST condition. When annealing was executed at 150°C and 200°C, notable improvements in tensile, anisotropic and fracture behaviour of UFG AA2099 were observed. There has been a significant enhancement in tensile strength, anisotropy and fracture toughness until temperature reaches 150°C being the highest (~506 MPa), whereas after 150°C, these properties have been shown to decrease notably. [ABSTRACT FROM AUTHOR]

The current trend in research on the physical properties of high-entropy alloys has been progressively increasing as there are many unknown possibilities for developing high-entropy alloys for advanced applications. This study investigated the effect of microstructures of rolled high-entropy alloy from the viewpoint of crystal orientation and dislocation density distribution to reproduce mechanical anisotropy using crystal plasticity finite element simulation. The crystal orientation and the geometrically necessary dislocation density of the rolled material were quantitatively estimated from experimental data of electron backscatter diffraction. Microstructural observation showed that particular textures were preferably oriented like in typical FCC metals. Even though the simulation results where only the preferred crystal orientation was considered did not show the expected mechanical anisotropy as in the experiment, the computational model with the dislocation density distribution and the preferred orientation showed the same tendency as the experiment. [ABSTRACT FROM AUTHOR]

In high-temperature and high-pressure environments, spring-energized seals (SES) play a crucial role in the petroleum and energy chemical industries. The circumferential springs within SES are responsible for generating sealing forces to maintain their performance. However, the intricate nonlinear behavior of these springs poses significant challenges in modeling and simulation. While several simplified models have been proposed to enhance computational efficiency, they often fall short under conditions of substantial deformation. Consequently, this paper introduces an anisotropic equivalent modeling approach, which takes into account the mechanical anisotropy of the springs. By applying the principles of using the same structural dimensions and equivalent mechanical properties, the parameters of the springs are transformed into equivalent parameters on anisotropic materials. The efficacy of this new model is validated through finite element simulations and lateral compression experiments, where its advantages over existing models in terms of predictive accuracy and computational efficiency are discussed. The results indicate that this novel model significantly improves predictive accuracy under conditions of substantial deformation, accompanied by enhancements in computational efficiency. This approach offers a promising tool for designing and predicting the performance of circumferential springs and SES. [ABSTRACT FROM AUTHOR]

This work investigates the influence of initial microstructure characteristics on the creep age forming behavior, mechanical anisotropy and fatigue crack growth resistance of creep age formed components. Components made by 2050 Al–Li alloy with fine, coarse and fibrous grain structures were prepared. The results indicate that the components with fibrous grains significantly increases the creep strain, which were generated by large-strain pre-deformation. Additionally, these components exhibit the highest yield and ultimate tensile strengths. On the other hand, components with coarse grains demonstrate superior fatigue crack growth resistance compared to other microstructures. Conversely, components with fine grains exhibit the lowest in-plane anisotropy value. The fatigue crack growth resistance of the three microstructures follows a descending order of coarse grains, fine grains, and fibrous grains. For applications requiring less anisotropy, the AA2050 alloy with fine grains is recommended. Conversely, the alloy with coarse grains is suitable for components subjected to cyclic loading. Lastly, the alloy with fibrous grains is ideal for structural components due to its high ultimate tensile strength and creep strain. [ABSTRACT FROM AUTHOR]

There has been a growing interest in utilizing 3D printing technology for military and civil defense engineering, especially in enhancing the resilience of infrastructure against impacts. Due to its distinctive additive manufacturing process, 3D printed concrete (3DPC) shows anisotropic behavior when subjected to static loads. However, research on its performance under dynamic conditions remains limited. Therefore, this study explores the characteristics of 3DPC under static and dynamic loads. Quasi-static results showed that incorporating textile significantly enhanced the deformation capacity of specimens, with the ultimate deflection and flexural toughness of basalt textile reinforced specimens in the X direction reaching 1.07 mm and 4206.9 N·mm, which are 118 % and 117 % higher than control specimens without textiles, respectively. The mechanical properties of 3DPC specimens showed increasing trend from static to impact loads. The impact results indicated that the peak load increased with the increase in impact energy. Adding two types of textiles showed different anisotropic mechanical properties which are associated with the patterns of cracking and failure. The addition of basalt textiles primarily enhanced the energy dissipation properties of 3DPC, with increases up to 98.2 %. The AR-glass textile was superior in terms of maintaining peak force under multiple impacts.

ABSTRACT3D-printed HA-PLA composites have attracted much attention because of their excellent biodegradability and osteointegration properties. However, HA particles negatively affect the mechanical properties of the composite parts. In this study, ultrasonic vibration-assisted 3D printing was used to improve the mechanical properties of HA-PLA composite specimens, and the effects of different infill angles and ultrasonic vibration power on the mechanical properties were investigated. The results demonstrated that the degradation and anisotropy of the mechanical properties of HA-PLA composites were alleviated by the use of ultrasonic vibration. By applying the ultrasonic vibration, the tensile and flexural strengths of the 20 wt% HA-PLA specimens fabricated with a 90° infill angle demonstrated the largest improvement of 104.3% and 112.7%, respectively. The high-frequency ultrasonic vibration waves promoted the spreading and fusion of the extruded materials, thereby reducing overlapping voids within the specimens and improving the interface bonding strength, also facilitated the refinement and dispersibility of the HA particles, which inhibited the formation of stress concentrations within the specimens and ultimately improved the mechanical properties. The printing process developed in this study can also be adapted to other particle (or other reinforcement types) reinforced composite to improve their mechanical performance.

The deformation behavior and mechanical properties of ZBHO x ceramic (ZrB 2 based ceramics with different amounts of (HfO 2 + 2 vol% CaO), x = 10 - 25 vol%) have been investigated. The results demonstrated that the flow stress of ZBHO x ceramic decreased with an increase in the (HfO 2 +2 vol% CaO) addition at the same strain rate. The flow stress decreased from ∼178 MPa for ZBHO 10 to ∼13 MPa for ZBHO 20 at 1700 °C and a strain rate of 2 × 10−4 s−1, representing a reduction of an order of magnitude. The intergranular deformation twinning and the amorphous phase contribute to the grain boundary sliding and grain rotation of the boride matrix grains, resulting in a significant reduction in flow stress. The matrix grains orientations on the P face (the face perpendicular to the extrusion direction) primarily tend to be along the {0001} plane, while that on the V face (the face parallel to the extrusion direction) tend to be along the {-12-10} plane or {01–10} plane. The textured ZBHO x ceramics exhibit distinct mechanical anisotropy because of the significant orientation difference in the microstructure. The hardness of textured ZBHO x ceramics on V face is higher than that on P face. And the fracture toughness of ZBHOx ceramics exhibits anisotropy on the V face, the fracture toughness in the V-o direction (the direction perpendicular to the P face) is higher than that in V-p direction (the direction parallel to the P face) of ZBHO x ceramics. The intergranular oxide twins synergistically collaborate with the grain rotation within the boride matrix, fostering favorable conditions for texture development. Besides that, the amorphous phase at the interface, characterized by a substantial presence of vacancies and defects, functions as a source of vacancies that facilitates diffusion deformation along the grain boundaries. Simultaneously, the emergence of an amorphous phase at grain boundaries or triple grain junctions further enhances grain boundary sliding and grain rotation of ZrB 2 and B 4 ZrHf grains. [Display omitted] • Mechanically anisotropic textured ZrB 2 ceramics were successfully prepared through the sintering-forging method. • By controlling the content of (HfO 2 +2 vol% CaO), the flow stress of ZrB 2 can be reduced by an order of magnitude. • The formation of oxide twins and amorphous phase facilitate grain boundary sliding and grain rotation of ZrB 2 grains. [ABSTRACT FROM AUTHOR]

In order to reveal the relationship between microstructure inhomogeneity and mechanical anisotropy, the Al–Cu–Li alloy 100 mm thick plate for aerospace was evaluated. The grain structure, crystallographic texture, phase structure and fractography of different thickness positions and directions were observed by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The in-plane and through-thickness anisotropy were characterized by tensile properties, fracture toughness and hardness tests. The results demonstrate a greater in-plane anisotropy in yield strength at the same thickness position of the plate. The Brass texture component increases successively at T, T/4, and T/2 positions, while the Cu texture component exhibits minimal variation. The in-plane anisotropy mainly arises from the Brass texture. Through-thickness anisotropy in the same direction is primarily influenced by the diameter, number density, and volume fraction of the T1 strengthening phase. The average diameter and number density of the primary strengthening phase T1 within grains are highest at the T/2 position and lowest at the T position. The plate contains unrecrystallized, elongated pancake-like grains along the rolling direction. Fracture toughness tests conducted in the L-T and T-L directions predominantly reveal dimple-type transgranular shear fractures, while the S-L direction exhibits intergranular fracture as the primary characteristic. The crack divider delamination toughening mechanism is the main contributor to higher fracture toughness values in the L-T and T-L directions compared to those in the S-L direction. The results reveal the corresponding relationship between the microstructure inhomogeneity and the mechanical anisotropy of Al–Li alloy ultra-thick plates, and provide ideas for the adjustment of process parameters during processing deformation and the regulation of microstructure during heat treatment of large-scale Al–Li alloy thick plates, which has engineering application reference value.

In this study, we investigated the mechanical and tribological properties of the layer-by-layer structure of additively manufactured implant-grade Polyether Ether Ketone (PEEK) through the Material Extrusion (ME) process as a potential substitute for artificial joints. The effective elasticity modulus of the anisotropic 3D-printed PEEK was determined to be 2.505 GPa along the vertical and horizontal build orientations. The lubricated friction and wear performance were assessed using a pin-on-disk test under various loads, including 14, 30, 50, and 70 N, with a sliding speed of 50 mm/s over a total distance of 1 km at 37 °C. The contact parameters between the hemispherical steel pin and 3D-printed PEEK disks, involving contact pressures over the circle of contact, were observed to increase as the load increased. The results indicated that the wear coefficient exhibited a rise from 1.418 × 10−5 to 2.089 × 10−1 as the applied loads increased, signaling a shift from mild to severe wear regimes. Fetal Bovine Serum (FBS) as a lubricant exhibited a mixed mechanism, ascertained through the Stribeck curve, as well as a minimum fluid film thickness of 1.346 nm under an isoviscous–elastic regime, as calculated by the maximum load. Moreover, the mechanism governing wear during sliding, influenced by both normal axial and shear loads, primarily involved adhesion.

In this work, the microstructure and texture of Mg-1.0Al-xZn-0.2Mn-0.5Ca (wt.%, x = 0, 1) alloys, which were produced via conventional casting or twin roll casting (TRC), were investigated, and their relation to the mechanical properties of the sheets at the final gage was analyzed. In the Zn-containing AZMX1100 alloy sheets, the amount and size of the secondary phases were significantly reduced, in comparison to the Zn-free AMX100 alloy sheet. The TRC sheet shows a smaller grain structure and fine secondary phases in comparison to the sheets produced via the conventional casting process. The texture of the AMX100 sheet is characterized by the basal poles tilted in the sheet rolling direction (RD). In the AZMX1100 sheets, the texture with the tilted basal poles towards the RD and transverse direction (TD) was developed after recrystallization annealing, while the tilting angle of the basal pole in the TD is larger than in the RD. There is no significant difference in the texture between the sheets produced by the casting and TRC process. The highest yield strength was obtained in the AZMX1100 sheet produced by the TRC process, and all examined sheets showed the mechanical anisotropy in accordance with their textures. [ABSTRACT FROM AUTHOR]

Reef limestone is a biogenic sedimentary rock widely distributed in coral reef areas, acting as an important foundation for coast construction. Due to its special biogenic origin, reef limestone is different from conventional rocks both in terms of rock structure and mechanical properties. In this study, mesoscale uniaxial compression experiments with five different loading directions were conducted on two kinds of reef limestones from the Maldives Islands and the South China Sea, respectively. The real-time high-resolution videos and images of failure processes were recorded simultaneously to investigate the fracture evolution and fracture surface roughness of reef limestones. It demonstrated that the reef limestones belonged to extremely soft to soft rocks, and their uniaxial compressive strength (UCS) values fluctuated with high discreteness. The mesoscale mechanical properties of reef limestones were highly anisotropic and mainly controlled by pore structure. The occurrence of dissolution pores in reef limestone tended to intensify mechanical anisotropy. With the integration of the fracture initiation and propagation features of reef limestones, it is supposed that the intrinsic mechanism of anisotropy was probably attributed to the differences in coral growth direction and dissolution. Furthermore, the quantified fracture surface roughness was revealed to have a good consistency with density and UCS for the reef limestones from the South China Sea. The findings are helpful for providing theoretical and experimental references for engineering construction in coral reef areas.

This study aims to investigate the anisotropic fracture toughness of an α+β titanium alloy processed by β forging. A typical basket-weave microstructure is observed, including the primary α (αp) phase, micron-scaled secondary α (αs) phase and residual β phase. The tensile test results show that the anisotropic strength results from the fine grain strengthening as well as the texture strengthening, and the plasticity difference is determined by the normal stress acting on the main crack in the fracture process. The orientation of the specimen also has a significant impact on fracture toughness. The corresponding toughening models of underlying damage mechanism with different orientations are proposed and discussed. It is found that the internal toughening mechanism is dominant, and external toughening mechanism also plays an important role in fracture toughness, including delamination and crack deflection caused by elongated β grains arrangement. Finally, the differences of J-integral resistance curves with different orientations are investigated in detail. The strength and fracture toughness values, KJIC (crack-initiation toughness) and KSS (growth toughness), are both highest when loading along radial direction (RD), and the positive effects of β grain morphology and two-phase texture on anisotropy of KJIC are summarized.

Mg–Al series sheets usually exhibit an apparent mechanical anisotropy induced by strong basal texture. In this study, a near-isotropic Mg–4.5Al–1.5Sn–0.5Ca–0.2Mn (ATXM5210) alloy was developed via 0.05 wt.% Sr micro-alloying combined with rotated rolling, displaying an ultra-low difference in yield strength (∼5 MPa), ultimate tensile strength (∼2 MPa) and elongation (∼1 %) between the rolling direction (RD) and transverse direction (TD), in contrast to a strong anisotropy of Sr-free alloy. We comparatively investigated the effect of trace Ce, Sm and Sr addition on the microstructure, texture evolution and mechanical properties of rolled ATXM5210 alloy. Specially, Sr-containing alloy possesses a more uniform distribution of finer CaMgSn particles after rolling, whereas coarse particles and particle bands are still distinctive in Sr-free alloys. Furthermore, the addition of Sr contributes to form broader-distributed texture towards both RD and TD with reduced peak intensity (∼10.8), leading to an apparently reduced mechanical anisotropy. The quite low mechanical anisotropy and balanced combination of yield strength (∼220 MPa) and ductility (∼21 %) make the present ATXM5210-0.05Sr alloy suitable for producing intermediate or final products and competitive for various engineering applications.

The mechanical anisotropy of selective laser melted (SLM) aluminum alloys resulting from heterogeneous grain structures is still not fully understood due to lacking study of grain orientation related mechanical response. Here, by introducing in-situ EBSD tensile method, the orientation induced anisotropy coefficient Ka related to the deformation-induced grain rotation was revealed by excluding effects of grain size and grain aspect ratio. Compared with traditional mechanical properties models by Taylor factor M, it was found that the orientation in as-built and in heat treatment contributed the most yield strength anisotropy, and introducing Ka predicts the mechanical anisotropy more accurately.

Palladium (Pd) and its alloys, renowned for their good corrosion resistance, catalytic efficiency, and hydrogen affinity, find extensive use in various industrial applications. However, the susceptibility of pure Pd to hydrogen embrittlement necessitates alloying strategies such as Pd-Ag systems. This study investigates the impact of the ordering on the phase stability and elastic properties of Pd-Ag alloys through first-principles calculations. We explore a series of ordered phase structures alongside random solid solutions using Special Quasirandom Structures (SQSs), evaluating their thermodynamic stability and elastic properties. Our findings indicate the possible existence of stable ordered L12 Pd3Ag and PdAg3 and L11 PdAg phases, which are thought to exist only in Cu-Pt alloys. An analysis of the elastic constants and anisotropy indices underscores some pronounced directional dependencies in the mechanical responses between the random solid-solution and ordered phases. This suggests that the ordered phases not only are thermodynamically and mechanically more stable than solid-solution phases, but also display a decrease in anisotropy indices. The results provide a deeper understanding of the atomic behavior of Pd-Ag alloys, and shed light on the design of multiphase Pd-Ag alloys to improve their mechanical properties.

The mechanical and thermodynamic behaviors of intermetallics in Al–Zn–Mg–Cu alloys are studied by first-principles calculations. All studied second phases have negative values of formation enthalpy and cohesive energy indicating their excellent thermodynamic stability. Al3Er_D0 2 2 has the most significant metallic nature, while Mg2Si shows the least metallicity. TiAl3 shows the highest bulk, shear, and Young's moduli. All Al3M polymorphs, Mg2Si and TiAl3 phases show covalent/metallic hybrid bonding. The mechanical anisotropic behaviors obey the trend of: MgZn 2 > Al 3 Er_D0 2 2 > Al 3 Sc_D0 2 2 > TiAl 3 > Al 3 Sc_D0 2 3 > Al 3 Er_D0 2 3 > Al 3 Er_L1 2 > Al 3 Sc_L1 2 > Mg 2 Si, where MgZn2 is the most mechanically anisotropic phase. The calculated room-temperature linear thermal expansion coefficient values for the studied phases are from 1 0. 2 × 1 0 − 6 K − 1 to 2 1. 2 × 1 0 − 6 K − 1 ; where Al3Er_L12 has the highest value (1 7. 3 × 1 0 − 6 K − 1) , followed by Al3Sc_L12 (1 5. 5 × 1 0 − 6 K − 1) ; both of which are close to that of the Al matrix, thus making the relatively lower thermal misfit. [ABSTRACT FROM AUTHOR]

Due to its large number of advantages compared to traditional subtractive manufacturing techniques, additive manufacturing (AM) has gained increasing attention and popularity. Among the most common AM techniques is fused filament fabrication (FFF), usually referred to by its trademarked name: fused deposition modeling (FDM). This is the most efficient technique for manufacturing physical three-dimensional thermoplastics, such that FDM machines are nowadays the most common. Regardless of the 3D-printing methodology, AM techniques involve layer-by-layer deposition. Generally, this layer-wise process introduces anisotropy into the produced parts. The manufacturing procedure creates parts possessing heterogeneities at the micro (usually up to 1 mm) and meso (mm to cm) length scales, such as voids and pores, whose size, shape, and spatial distribution are mainly influenced by the so-called printing process parameters. Therefore, it is crucial to investigate their influence on the mechanical properties of FDM 3D-printed parts. This review starts with the identification of the printing process parameters that are considered to affect the micromechanical composition of FDM 3D-printed polymers. In what follows, their (negative) influence is attributed to characteristic mechanical properties. The remainder of this work reviews the state of the art in geometrical, numerical, and experimental analyses of FDM-printed parts. Finally, conclusions are drawn for each of the aforementioned analyses in view of microstructural modeling. [ABSTRACT FROM AUTHOR]

A fabric hydrogel composite hernia mesh with biomechanical and mesh-tissue interface dual compliance is designed for scarless abdominal wall reconstruction. The mesh is composed of a polyester knitted fabric and chitosan-polyacrylamide hydrogel complex. The mechanical properties of the composite mesh are adjusted to resemble the human abdominal wall by alkali treatment of chitosan to achieve good biomechanical compliance. An adhesion group is introduced into the composite mesh that forms covalent bonds with tissue, eliminating the need for suturing, reducing stress concentration at the fixation site, achieving mesh-tissue interface compliance, and improving the simplicity of the operation. Covalent bonds and hydrogen bonds make the mesh have strong adhesion (70.1 ± 3.2 kPa) and repeatable (four times) robust adhesiveness. In vivo experiments using a rabbit abdominal wall defect model demonstrate quick adhesiveness and excellent functional reconstruction. Biomechanical and mesh-tissue interface dual compliance allow the tissue to regenerate an intact abdominal wall structure. The adhesive fabric hydrogel composite hernia mesh offers significant clinical values for repairing abdominal wall defects and provides design ideas for repairing other load-bearing soft tissues. [ABSTRACT FROM AUTHOR]

The mechanical anisotropy of selective laser melted (SLM) aluminum alloys resulting from heterogeneous grain structures is still not fully understood due to lacking study of grain orientation related mechanical response. Here, by introducing in-situ EBSD tensile method, the orientation induced anisotropy coefficient Ka related to the deformation-induced grain rotation was revealed by excluding effects of grain size and grain aspect ratio. Compared with traditional mechanical properties models by Taylor factor M, it was found that the orientation <001 > in as-built and <102 > in heat treatment contributed the most yield strength anisotropy, and introducing Ka predicts the mechanical anisotropy more accurately. By introducing in-situ EBSD tensile method, we found the orientation induced anisotropy coefficient can reflect the mechanical anisotropy by excluding effects of grain size and grain aspect ratio. [ABSTRACT FROM AUTHOR]

Cryogelation is a powerful technique for producing macroporous hydrogels called cryogels. Although cryogelation reactions and cryogels were discovered more than 70 years ago, they attracted significant interest only in the last 20 years mainly due to their extraordinary properties compared to the classical hydrogels such as a high toughness, almost complete squeezability, a mechanically stable porous structure with honeycomb arrangement, poroelasticity, and fast responsivity against external stimuli. In this mini review, general properties of cryogelation systems including the cryoconcentration phenomenon responsible for the unique properties of the cryogels are discussed. The squeezability and poroelasticity of cryogels comparable to those seen with articular cartilage are also discussed. Cryogelation reactions conducted within the pores of preformed cryogels and some novel cryogels with attractive properties are then discussed in the last section. [ABSTRACT FROM AUTHOR]

3D printing (3DP) technology is a groundbreaking technology that can offer valuable insight into rock characterization and theoretical model verification due to its specimen reproducibility and unprecedented flexibility in manufacturing various structural shapes. Previous studies have explored the effect of printing direction on the mechanical properties of 3D-printed rocks, but the underlying cause of macroscopic mechanical anisotropy in 3D-printed gypsum rocks remains unclear. In this study, the effect of the movement direction of the printer head and bedding plane on macroscopic mechanical behavior and failure modes of 3D printed gypsum rocks were investigated. Uniaxial compression tests were conducted to investigate the mechanical properties of 3D-printed gypsum rocks. Along with the mechanical studies, the composition change of the raw powder before and after printing was studied based on particle size diameter (PSD), x-ray diffraction (XRD), and thermogravimetric differential thermal analysis (TG–DTA) experiments. Furthermore, Micro-CT imaging was conducted to investigate the microstructural characteristics of 3D-printed rocks (e.g. pore size, pore shape, and pore anisotropy). The results indicated that 3DP gypsum specimens printed on the yoz plane, which were only affected by the bedding direction, exhibited the lowest strength and mechanical anisotropy. In contrast, specimens printed on the xoy plane, influenced solely by the movement direction of printer head, showed the highest strength. Specimens printed on the xoz plane displayed the greatest mechanical anisotropy due to the joint effect of the bedding direction and the movement direction of the printer head. In terms of strength and mechanical anisotropic properties of 3D-printed specimens, the movement of the printer head was found to be more significant than the bedding direction, whereas the bedding direction was more crucial for peak strain. As for the failure mode, most of the 3D-printed specimens failed by shear failure of which the bedding planes played an important role in the specimens with small inclined angles. Highlights: This study investigated the effect of the movement direction of the printer head and bedding planes on mechanical anisotropy and the failure mode of 3DP gypsum rocks. Three types of experiments were conducted to enhance the understanding of how material composition and microstructure impact the macroscopic mechanical response of 3DP gypsum rocks. Micro-CT scanning tests were performed to reveal the failure mode and microstructural characteristics of 3D printed gypsum rocks. [ABSTRACT FROM AUTHOR]

This paper presents modeling of mechanical anisotropy in argillaceous rocks using an irregular lattice modeling approach, namely the rigid-body-spring network. To represent the mechanical anisotropy, new schemes are implemented in the modeling framework. The directionality of elastic deformation is resolved by modifying the element formulation with anisotropic elastic properties. The anisotropy of strength and failure characteristics is facilitated by adopting orientation-dependent failure criteria into the failure model. The verification of the improved modeling procedures is performed against theoretical model predictions for unconfined compression tests with various bedding orientations. Furthermore, excavation damage and fracturing processes in rock formations are simulated for different geomechanical configurations, such as rock anisotropy and tectonic heterogeneity. The simulated excavation damage characteristics are realistic and comparable with the actual field observation at a tunnel located in an argillaceous clay formation. The simulation results provide insights into the excavation damage zone phenomena with an explicit representation of fracturing processes.

This paper presents modeling of mechanical anisotropy in argillaceous rocks using an irregular lattice modeling approach, namely the rigid-body-spring network. To represent the mechanical anisotropy, new schemes are implemented in the modeling framework. The directionality of elastic deformation is resolved by modifying the element formulation with anisotropic elastic properties. The anisotropy of strength and failure characteristics is facilitated by adopting orientation-dependent failure criteria into the failure model. The verification of the improved modeling procedures is performed against theoretical model predictions for unconfined compression tests with various bedding orientations. Furthermore, excavation damage and fracturing processes in rock formations are simulated for different geomechanical configurations, such as rock anisotropy and tectonic heterogeneity. The simulated excavation damage characteristics are realistic and comparable with the actual field observation at a tunnel located in an argillaceous clay formation. The simulation results provide insights into the excavation damage zone phenomena with an explicit representation of fracturing processes.

An arterial vessel has three layers, namely, the intima, the media and the adventitia. Each of these layers is modeled to have two families of strain-stiffening collagen fibers that are transversely helical. In an unloaded configuration, these fibers are coiled up. In the case of a pressurized lumen, these fibers stretch and start to resist further outward expansion. As the fibers elongate, they stiffen, affecting the mechanical response. Having a mathematical model of vessel expansion is crucial in cardiovascular applications such as predicting stenosis and simulating hemodynamics. Thus, to study the mechanics of the vessel wall under loading, it is important to calculate the fiber configurations in the unloaded configuration. The aim of this paper is to introduce a new technique of using conformal maps to numerically calculate the fiber field in a general arterial cross-section. The technique relies on finding a rational approximation of the conformal map. First, points on the physical cross section are mapped to points on a reference annulus using a rational approximation of the forward conformal map. Next, we find the angular unit vectors at the mapped points, and finally a rational approximation of the inverse conformal map is used to map the angular unit vectors back to vectors on the physical cross section. We have used MATLAB software packages to achieve these goals.

3D printing is a manufacturing technique based on the structuring of parts layer by layer. This principle yields a specific printing direction, that is the spatial orientation of the produced layers. Thus, potential anisotropy arising from the printing direction is a major concern in 3D printing. The mechanical properties of a biocompatible resin mainly consisting of methacrylates and tricalcium phosphate particles is examined. Various tests are conducted to examine the mechanical anisotropy of testing samples manufactured with a 3D printer based on stereolithography. A digital light processing unit (λ = 375 nm) is utilized to produce test samples in three orthogonal directions. Bending behaviour, fracture toughness, and hardness are measured. Furthermore, light microscopy is utilized to assess the properties of the fractured samples qualitatively. Assessed values are in agreement with comparable materials and show no statistically significant (p = 0.095) evidence of anisotropic behaviour. Sample orientation has no impact on the mechanical properties of the produced parts. Thus, production time and capabilities can be optimized by varying and combining sample orientation without changing the mechanical performance of the engineered parts significantly.

3D printing geopolymer is a new type of building way and material with both of resource utilization and intelligent building. The mechanical properties in all directions and the bonding strength between layers of components are important factors affecting the constructability and durability of buildings.3D printing geopolymer mortar was prepared with fly ash and quartz sand as main raw materials, anhydrous sodium silicate as alkali activator, slag powder as auxiliary cementitious material, magnesium aluminum silicate as special additive. The 3D printing component of fly ash-based geopolymer was prepared under the condition of the optimum dosage and proportion. The interlayer bonding strength and tensile strength were studied, and the mechanical anisotropy properties were characterized by mechanical properties and ultrasonic pulse velocity.

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Thermoplastics, which are used in widely various applications from consumer goods to automobiles, are lighter than metals and ceramics and have excellent moldability. Injection molding is often used as a thermoplastic molding process because it can achieve near-net-shape molding and because it has excellent mass production capabilities. Injection molded products have a hierarchical structure, with the surface area contacting the mold designated as the skin layer and the interior of the molded product broadly identified as the core layer. The molecular orientation formed by the melt molding process is strongly dependent on the flow direction. Quantifying anisotropy is extremely important when discussing the mechanical properties of thermoplastic molded products. This study clarifies whether the mechanical anisotropy of polymer injection molded products can be evaluated quantitatively using short-beam shear testing. This study also elucidates the quantitative significance of the quantitative values.Results show that the shear stress components in each direction obtained from the short-beam shear test are components of the yield initiation shear stress under uniaxial tensile loading resolved in each direction. To quantify the degree of stress concentration attributable to the internal structure of the molded product, the ratio of the yield initiation shear stress to the shear stress components in each direction was divided by √3. Comparison of the degree of stress concentration with the shear stress components generated in the short beam shear test showed the thickness direction as weakest against shear stress and showed the width direction as the strongest.

In this work, the microstructure and texture of Mg-1.0Al-xZn-0.2Mn-0.5Ca (wt.%, x = 0, 1) alloys, which were produced via conventional casting or twin roll casting (TRC), were investigated, and their relation to the mechanical properties of the sheets at the final gage was analyzed. In the Zn-containing AZMX1100 alloy sheets, the amount and size of the secondary phases were significantly reduced, in comparison to the Zn-free AMX100 alloy sheet. The TRC sheet shows a smaller grain structure and fine secondary phases in comparison to the sheets produced via the conventional casting process. The texture of the AMX100 sheet is characterized by the basal poles tilted in the sheet rolling direction (RD). In the AZMX1100 sheets, the texture with the tilted basal poles towards the RD and transverse direction (TD) was developed after recrystallization annealing, while the tilting angle of the basal pole in the TD is larger than in the RD. There is no significant difference in the texture between the sheets produced by the casting and TRC process. The highest yield strength was obtained in the AZMX1100 sheet produced by the TRC process, and all examined sheets showed the mechanical anisotropy in accordance with their textures.

In order to further explore the effect of pre-aging treatment on large-scale alloys, a pre-aging extruded Mg-9.32Gd-4.02Y-2.16Zn-0.48Zr (wt.%) alloy with large extrusion ratio (ER = 19.5) and extrusion temperature of 450 °C in large-scale (Φ308 mm × 800 mm) was investigated in this paper. It exhibited good properties and a more pronounced anisotropy. The comprehensive performance in the 45° direction was the best. The extrusion direction (ED) presented a high strength, while the transverse direction (TD) showed poor strength and ductility contemporaneously. The main results of strength anisotropy were the alignment orientation of the long-period stacking ordered (LPSO), fine grain strengthening, and texture strengthening. The c-axis of most of the grains in TD samples was perpendicular to the direction of applied stress because of the abnormal //ED texture, which reduced the ductility. In addition, the formation mechanism of abnormal texture has also been studied. The higher extrusion temperature reduced the critical shear stress (CRSS) of the non-basal slip system, and the higher strain promoted the rotation of the base plane along the principal stress axis under the operation of continuous non-basal slip, resulting in the abnormal //ED texture due to lattice rotation. On the other hand, dynamic recrystallization (DRX) also greatly affected the generation of the abnormal texture. Firstly, DRX produced a proportion of grains with a nucleation orientation of , then the subsequent preferential growth of DRX grains led to the vast majority of grains with an orientation tending towards . However, the former has less effect on abnormal texture than the latter.

Mechanical anisotropy greatly influences the applications of materials printed by additive manufacturing techniques such as Multi Jet Fusion (MJF) and selective laser sintering. However, the mechanical anisotropy of MJF-printed fibre–reinforced polymer composites has not been well understood. In this work, the effect of the fibre length on the mechanical performance of MJF-printed glass fibre–reinforced polyamide 12 (GF/PA12) composites is systematically investigated. Both experimental and simulation results confirm that longer fibres are in favour of fibre alignment in the powder spreading direction. The composite parts with longer fibres exhibit higher porosity. When GFs with an average length of 226 μm are added, the ultimate tensile strength and tensile modulus of the composites measured in the powder bed spreading direction are remarkably improved by 51% and 326%, respectively, as compared with those of neat PA12 specimens. This work provides guidance for the printing of other high-strength fibre–reinforced polymer composites.

This study aims to strengthen carbon nanotube (CNT)/Al composites, which were fabricated by a combination of spark plasma sintering (SPS) and repeated hot rolling techniques. Dry ball milling was conducted to uniformly disperse CNT in Al powders. The microstructures of the CNT/Al composites including dispersibility of CNT were observed using a scanning electron microscope (SEM) and transmission electron microscope (TEM). Ball milling treatments promoted to reduce the number of CNT aggregations and increase C concentrations in the CNT aggregations in the composites. Anisotropic tensile behavior was also investigated, which demonstrated that the post-SPS repeated hot rolling can highly enhance the tensile strength as well as deformability of the composites. [ABSTRACT FROM AUTHOR]

Melt electrowriting (MEW) enables the electric field‐assisted digital fabrication of precisely defined scaffold architectures of micron‐sized fibers. However, charge accumulation and consequent disruption of the precoded pattern by fiber bridging prevents controlled printing at small interfiber distances. This, together with the periodical layer stacking characteristic for additive manufacturing, typically results in scaffolds with channel‐like macroporosity, which need to be combined with other biofabrication techniques to achieve the desired microporosity for cellular infiltration. Therefore, a design strategy is devised to introduce controlled interconnected microporosity directly in MEW scaffolds by an algorithm that creates arrays of bridging‐free parallel fibers, angularly shifted from layer to layer and starting at a random point to avoid periodical fiber stacking, and hence channel‐like pores while defining micropores. This work hypothesizes that pore size can be controlled, decoupled from fiber diameter, and the mechanical properties, including anisotropy ratio, can be tuned. The authors demonstrate this while leveraging the platform for both flat and seamless tubular scaffolds and characterize them via micro‐computed tomography and tensile loading. Lastly, successful cell ingrowth into the micropores and extracellular matrix formation are shown. This platform enables microporous scaffolds entirely via MEW that can be tailored to the architectural and mechanical requirements of the target tissues. [ABSTRACT FROM AUTHOR]

This study aims to strengthen carbon nanotube (CNT)/Al composites, which were fabricated by a combination of spark plasma sintering (SPS) and repeated hot rolling techniques. Dry ball milling was conducted to uniformly disperse CNT in Al powders. The microstructures of the CNT/Al composites including dispersibility of CNT were observed using a scanning electron microscope (SEM) and transmission electron microscope (TEM). Ball milling treatments promoted to reduce the number of CNT aggregations and increase C concentrations in the CNT aggregations in the composites. Anisotropic tensile behavior was also investigated, which demonstrated that the post-SPS repeated hot rolling can highly enhance the tensile strength as well as deformability of the composites. [ABSTRACT FROM AUTHOR]

A novel sp3 + sp2 hybridized carbon allotrope in the P4/mmm phase, denoted as tP48 carbon, is proposed and predicted according to density functional theory. The tP48 carbon allotrope is mechanically, dynamically, and thermodynamically stable. The bulk modulus, B, of tP48 carbon is slightly larger than that of other carbon allotropes in the tP family. Of the tP family of carbon materials, tP48 carbon exhibits the greatest anisotropy in terms of its Young's modulus, E, Poisson's ratio, v, and shear modulus, G. In regards to its electronic band structure, tP48 carbon is an indirect semiconductor material with a band gap of 1.516 eV. The XRD characteristics of tP48 carbon are also studied in this work, with the associated characteristics found to be of guiding significance for determining the structure of tP48 carbon in subsequent experiments. [ABSTRACT FROM AUTHOR]

Compressive and tensile properties of a carbon nanotube (CNT) reinforced 2024Al composite are investigated under quasi-static and dynamic compression as well as quasi-static tension, along three different directions (extrusion, normal and transverse directions). Upon compression, yield and fracture strengths of the composite show negligible strain rate effect and mechanical anisotropy as manifested in the compressive stress–strain curves. Fractography and profilometry show that fracture surfaces are rough shear fracture planes for quasi-static compression; however, smooth conical fracture surfaces are observed for dynamic compression as a result of more homogeneous damage nucleation and growth, leading to high ductility under high strain rate loading. Pronounced mechanical anisotropy is observed for the composite under quasi-static tensile loading. Ductility or fracture strain is the highest along the normal direction, because debonding along the particle and lamellar interfaces is suppressed along this direction. In situ optical imaging along with digital image correlation is utilized to obtain the deformation dynamics of the composite along the three different directions. Stripe-shaped strain localizations appear in the strain fields along the extruded and tangential directions, while the strain fields are approximately uniformly distributed along the normal direction, consistent with the stress–strain curves. [ABSTRACT FROM AUTHOR]

Anisotropic mechanical behavior of the Ti-6Al-4V alloy is essential for its forming and service. Generally, it is preferable to minimize the in-plane anisotropy of Ti-6Al-4V sheet. The present work investigates the anisotropy of Ti-6Al-4V alloy by tensile tests along the rolling direction (RD), transverse direction (TD), and diagonal direction (DD) of the sheet, evaluating the anisotropic yield and flow behaviors and exploring the causes of these anisotropic properties. The intrinsic deformation mechanism of Ti-6Al-4V alloy tensioned along different directions was studied with Schmid factor and kernel average misorientation (KAM) analysis. The samples tensioned along the RD and TD of the sheet (denoted as RD sample and TD sample) show similar yield stress, while tensile along the DD (denoted as DD sample) leads to lower yield strength. The mechanical anisotropy exhibited by the Ti-6Al-4V sheet is closely related to the crystallographic texture. The flow stresses of the RD and TD samples are higher than that of the DD sample due to the higher density of dislocations generated during the tensile deformation, in which prismatic 〈 a 〉 dislocations make a great contribution to coordinating plastic deformation. [ABSTRACT FROM AUTHOR]

The lithospheric strength is a key factor in controlling the lithosphere dynamics and deformations. The effective elastic thickness (Te) of the lithosphere can always be used to address the lithospheric strength. Hence, it is a powerful tool for studying the large-scale lithospheric structure. Estimates of Te over both continent and ocean are important for understanding the lithospheric strength with its lateral variations, crustal gravity isostatic state, lithospheric thermal state and rheological structure, and the coupling at the lithosphere-asthenosphere boundary. This article summaries the background of Te estimation and reviews the domestic and overseas research progress on the estimation methods. The main methods for estimating Te include forward modeling of deformations, spectral techniques (i.e., admittance and coherence) based on the cross-spectral analysis of the gravity and topography data, and direct estimations of Te based on the yield strength envelope. The method of deformation forward modeling estimates Te from the optimal lithospheric deflection model, with which the calculated theoretical gravity anomalies best fit the observed ones. The spectral technique calculates Te through analyzing the relationship between observed gravity and topography data in the spatial wavenumber domain, including admittance and coherence methods. The admittance method operates the Te estimation basically based on the spectrum ratio of the gravity to topography signals, while the coherence method works by examining the variation characteristics of the relationship between those two signals in wavenumber domain. Under long-wavelength loading, the lithosphere tends to act as a regional isostatic equilibrium mode. In this model, the lithosphere deflected and the gravity anomaly could be completely related to the topography, i.e., the correlation between those two is close to 1. In contrast, under short-wavelength loading, the lithosphere usually does not deflect due to the lithospheric strength, hence the gravity-topography correlation is close to 0. The gravity-topography correlation decreases from 1 to 0 with the wavenumber. The wavelength around the change point of the correlation with the value of 0.5 representing the state transition of the lithosphere from isostatic equilibrium to disequilibrium, is determined by the lithospheric strength, hence could be used to address Te. The yield strength envelope method estimates Te based on the rock mechanics experiments which usually study how strength varies according to temperature and composition of the crust and mantle lithosphere. Recently, with the development of modern digital signal processing technology, spectral techniques have gradually become the most popular approaches for the Te estimation. Calculating the observed admittance and coherence needs the gravity and topography auto-spectra and the cross-spectrum to be computed first. Those two spectra can be obtained using periodogram, maximum entropy, multitapers and wavelet methods. Periodogram is a direct spectral estimation method used up until the late 1990s，although it is not a very accurate one due to the spectral leakage. While maximum entropy spectral estimation can minimize the spectral leakage to some extent and yield accurate spectra in small-window spectral estimation, multitaper method deals with spectral leakage well circumvent the problem of small window sizes. The wavelet method has also been widely developed for computing spectra during Te estimation, because the wavelet transform can separate closely spaced and high-wavenumber features, whilst the windowed Fourier transform likely to smear the information, either in space or wavenumber depending on the window size. The anisotropy of the lithosphere is an important parameter of the lithospheric mechanical property and can largely affect the calculated Te values. To obtain reliable Te, the anisotropy of Te should be considered during the Te estimation. Moreover, Te anisotropy can affect the crustal stress state, crustal rheological properties, and microfractures developments. Those subjects can provide important clues for the study of breeding environments, occurrence processes, and mechanisms of earthquakes. This review also discusses the principles, advantages, and disadvantages of the estimation methods. Finally, this article provides avenues for future research.

The selective laser melting (SLM) technology is widely used to manufacture 316L stainless steel (SS) components for industrial applications. To understand the microstructure and the mechanical properties of additively manufactured 316L alloy, bulk materials were fabricated in longitudinal and transverse directions from which subset tensile specimens were then machine. Bulk materials were subjected to porosity detection with X-ray computed tomography and texture analysis with electron backscatter diffraction (EBSD). Microstructural investigations reveal that the SLM-built specimens had a porosity of 1.87%, and a preferential {110} orientation parallel to the build direction. The transverse specimens show significantly better properties in elastic modulus E (215.1�4.7GPa), yielding stress sy (548.2�8.3MPa) and ultimate tensile strength UTS (705.6�2.9MPa) than the longitudinal ones (E of 175.9�9.8GPa, sy of 495.3�15.5 and UTS of 608.8�3.6MPa). The anisotropic mechanical performance was attributed to the preferential {110} texture caused by thermal conditions during manufacturing and the embedded voids due to insufficient melting. A three-parameter Weibull distribution was adopted to further describe the mechanical anisotropy of SS316L based on stochastic experimental measurements. Fractography indicated the existence of manufacturing defects that drive to premature failure of SS316L specimens�around half SS316L specimens failed of elongation less than 0.4.

This work evaluates the stress relaxation behavior of textured Zircaloy-4 cladding to understand how mechanical anisotropy influences pellet-cladding interactions. Uniaxial and biaxial stress relaxation tests are performed using full-tube axial tension and internal pressurization, respectively, aiming to achieve 0.25 %, 1 %, and 2 % equivalent strains in the cladding samples at a temperature of 300 °C. Internal pressure relaxation test results display enhanced stress relaxation compared to axial testing results, particularly for samples loaded beyond yield. Results of electron backscatter diffraction indicate increased deformation microstructure during loading and increased strain homogenization and recovery during relaxation for samples loaded via internal pressurization. Analysis indicates that the increased production and activity of basal 〈 a 〉 dislocations play a significant role in the enhanced relaxation measured in samples subjected to internal pressurization. [ABSTRACT FROM AUTHOR]

The application of 3D printing technology to earth buildings conforms to the development concept of low carbon, green and intelligent construction. The key issue lies in the development of earth material with both favorable buildability and sufficient mechanical properties. In this study, the printing parameters of mixture for 3D printing with different water contents were optimized. The optimum water content of 3D printing cob was determined based on the buildability. The result shows that when the flow spreading diameter is between 140 mm and 160 mm, 3D printing cob has good buildability performance. The optimum water content is 24.6 %. In addition, anisotropic performance was analyzed by compressive strength tests from three orthogonal directions. In particular, according to the test results of single printing limit height and yield stress, the buildability of 3D printing cob wall was analyzed. The building strategy of the printing divided into multiple times was obtained. • Earth composite material was prepared for extrusion-based 3D printing. • Optimal printing parameters of 3D printing cob was determined. • Mechanical behaviors of 3D printing samples exposed to various loadings were tested. • Printing strategy of 3D printing cob wall was explored. [ABSTRACT FROM AUTHOR]

• This study introduces a new approach utilizing 3DP technology to fabricate bedded rocks, demonstrating its feasibility. • The study meticulously explores both the qualitative and quantitative impacts of bedding planes and flaws on the fracture behavior of soft 3DP bedded rocks. • Accurate determination of strength and strain is achieved through meticulous comparison of stress–strain curves and REVC-strain curves. • The implications of the study's findings for engineering failures are thoroughly discussed. Bedded rocks are a typical geological formation with significant implications for understanding tectonic evolution, rock engineering, and geological hazard mitigation. This study introduces a novel method for fabricating bedded rocks using 3D printing (3DP) technology. By comparing the mechanical anisotropic properties and failure modes of 3DP bedded rocks with natural bedded rocks, we validate the feasibility of this approach. Compression tests are conducted on 3DP bedded rocks containing a single flaw to investigate the coupled effects of bedding planes and flaws on the mechanical properties. Digital image correlation (DIC) is employed for full-field deformation measurement during loading, enabling the study of deformation and crack evolution patterns. The results indicate that bedding planes dominate the brittleness of 3DP bedded rocks containing a single flaw. Significant plastic characteristics and prolonged nonlinear deformation stages are observed when the bedding angle (α) is between 0° and 45°, while brittleness becomes apparent beyond 45°. Both strength and elastic modulus are decided by bedding planes and initial flaws. By comparing stress–strain curves and rate of effective variance change (REVC)-strain curves, crack initiation can be quantitatively identified, revealing a linear correlation between strength and stress values at crack initiation points. The bedding plane also dominates crack propagation and failure modes: when α ≤ 30°, cracks propagate through the bedding, indicating tensile failure; when 45° ≤ α ＜90°, cracks propagate along the bedding, indicating tensile-shear or shear failure; and when α = 90°, cracks propagate along bedding planes, indicating tensile failure. The findings of this study provide insights for explaining and predicting failure modes in engineering projects involving bedded rock formations, such as slopes, tunnels, and coal mines. [ABSTRACT FROM AUTHOR]