In this paper, we have investigated void growth in von Mises materials which contain realistic porous microstructures. For that purpose, we have performed finite element calculations of cubic unit-cells which are subjected to periodic boundary conditions and include porosity distributions representative of three additively manufactured metals. The initial void volume fraction in the calculations varies

The stress state-dependent plastic anisotropy of sheet metals has drawn significant attention. Nevertheless, existing phenomenological plasticity models limitedly capture the distinctive yield strengths and plastic flow (r-values) under a wide range of stress states covering uniaxial tension (UT), equi-biaxial tension (EBT), uniaxial compression (UC), plane strain tension (PS), and pure shear (SH)

This paper proposes a modelling approach that combines the discrete element method (DEM) and a novel bonded contact model to characterise the fatigue response of cemented materials. While DEM is commonly used to simulate bonded materials undergoing cracking, the centrepiece of the present method is the development of the novel bonded fatigue model. This new model couples damage mechanics and bounding

Having regard to the inherent crystal anisotropy characteristic of nickel-based single crystal and the actual industrial manufacture, and application of the turbine blade, a trade-off between orientation deviation and performance demands that attention should be paid to estimating the influences of orientation deviation from [001] to [011] on the mechanical properties of the nickel-based single crystal

Micro-twinning is the major creep deformation mechanism in most Ni-based superalloys at temperatures above 700 °C. Nevertheless, many aspects of twin nucleation and growth remain unexplored. The Kolbe mechanism for micro-twinning is currently widely accepted in the community to explain these processes, based on post mortem TEM characterization and indirect theoretical estimations. However, this does

Ti exhibits complex plastic deformation controlled by active dislocation and twinning systems. Understandings on dislocation cores and twin interfaces are currently not complete or quantitative, despite extensive experimental and simulation studies. Here, we determine the dislocation core, twin, and crack properties in both HCP and BCC Ti using a Deep Potential (DP), DFT and linear elastic fracture

It is challenging to precisely model the complicated plastic deformation of metals, including anisotropy in strength and plastic deformation, strength differential effect, anisotropic hardening, etc. A new approach is proposed to extend anisotropic yield functions into asymmetric ones by introducing a Lode dependent function. The approach is applied to the Hill48 function with a Lode-dependent function

Impact mechanics of micron-scale, Al-6061 particles on sapphire and Al-6061 substrates were investigated experimentally and through simulations. Particle impact experiments were carried out by using the laser induced projectile impact test (LIPIT) and the coefficient of restitution was evaluated for impact velocities in the range of 50–950 m/s. Bonding was observed only in Al-on-Al impacts with impact

This study proposes a machine learning-based constitutive model for anisotropic plasticity in sheet metals. A fully connected deep neural network (DNN) is constructed to learn the stress integration procedure under the plane stress condition. The DNN utilizes the labeled training data for feature learning, and the respective dataset is generated numerically based on the Euler-backward method for the

In fusion reactor environment, helium bubble acts as a crucial inducement to the performance degradation of plasma facing tungsten, leading to irradiation hardening and embrittlement. The dislocation interacted with helium bubble directly controls the service reliability and safety of irradiated materials. However, the fundamental question regarding the mechanism and quantitative model of this interaction

Boosting the applications of high nitrogen steels requires delicate control of detrimental brittle AlN precipitates which often initiate cracking and thus degrade overall mechanical performance. Here we report that stacking faults in nano-sized AlN precipitates can be activated by martensitic transformation during quenching in a high nitrogen martensitic stainless bearing steel. Atomic-scale structure

Statistical analysis of slip system identification and quantitative study on local plasticity is crucial to understand the collective deformation by the sub-grain-scale slip activities in polycrystalline metallic materials. In this study, an automated framework for identifying slip system and assessing strain localization of slip bands termed ASSISL (automated Slip System Identification and Strain

Shear localization is an important failure mode, or even the dominant mode in metals at high-strain rates. However, it is a great challenge to accurately predict the occurrence and evolution of shear localization in metals at the high-strain rate deformation. Here, a dislocation-based crystal plasticity constitutive model with a crucial mechanism of shear instability, namely dynamic recrystallization

This paper presents a novel mesoscopic damage model to characterize the low-cycle fatigue damage evolution of an extruded AZ31 magnesium (Mg) alloy, taking into account the effect of twinning. The damage caused by the slip bands (SBs)–twin boundaries (TBs) and SBs–grain boundaries (GBs) interactions is treated based on the Tanaka–Mura model and the Eshelby inclusion theory. Strain energy values at

The material behaviors under nonlinear strain paths have been successfully explained through distortional hardening model in which the yield surface is mainly rotating and contracting as plastic deformation occurs. In order to apply to industrial applications, it is beneficial for any constitutive model including distortional hardening model to have simplicity of equation, which is related to numerical

High temperature design requires accurate constitutive models to describe material inelastic deformation and failure behavior. Oftentimes, calibrating accurate models devolves into the problem of fitting the model parameters against experimental test data. Here, we present the pyopmat package, an open source framework for calibrating constitutive models against experiment data subjected to various

Additively Manufactured (AM) metallic alloys differ from their conventionally produced counterparts by complex multi-scaled microstructures leading to deeply modified mechanical behavior. The characterization of these new links between microstructure and mechanical properties is of first importance. Nevertheless, many alloys produced by Laser Powder Bed Fusion (LPBF) process exhibit multi-phase microstructures

The functional devices made by NiTi shape memory alloys (SMAs) are often serviced in hydrogen (H)-rich environment. Recently experimental results showed that the martensite transformation (MT) of NiTi SMA changed strongly after charging H, which originates from the H diffusion in the material and an additional transformation resistance caused by the absorbed H atoms. In this work, a multi-scale di

Cyclic responses of a novel heat resistant martensitic steel, 9Cr3Co3W1CuVNbB steel, under different loading modes were studied to reveal its complex strengthening mechanisms at high temperature. Based on the experimental observations, dislocation strengthening, precipitation strengthening by M23C6 phase, MX phase, and Cu-rich phase, and subgrain boundary strengthening were the main mechanisms for

Circular holes on single crystal (SX) superalloys are widely utilized as film cooling structures on SX turbine blades, while their failure is a persistent issue. This study presents in-situ tests using digital image correlation (DIC) to reveal the slip band (SB) evolution behavior near the circular hole on SX superalloy, and proposes a mechanism-based model to capture the SB-associated evolutions of

Ductile failure under plane stress conditions is analyzed at the meso-scale using periodic unit cell model simulations of void growth in a plastically deforming matrix. Equivalent strains to failure by the onset of plastic instability at the macro-scale are estimated using the loss of ellipticity criterion for the equilibrium equations. Failure loci obtained from the cell model simulations are compared

In this paper, we shall present a new micromechanical damage model for capturing the mechanical behaviors of quasi-brittle geomaterials under a wide range of compressive stress. Two essential coupled non-linear mechanisms are taken into account: plastic deformation related to frictional sliding along the microcrack surfaces, and microscopic damage induced by the initiation and propagation of microcracks

While the grain size effect (GSE) is universally observed in polycrystalline metals and alloys, extended dislocation pileups (DPUs) at grain boundaries (GBs) are rarely observed. Although this discrepancy was noticed over 50 years ago, DPUs are still widely accepted as the explanation for the GSE, often expressed as the Hall-Petch (HP) relationship. To provide a quantitative assessment of the pileup

Shock wave experiments show that many annealed face-centered cubic metals exhibit an anomalously increasing yield strength with temperature at high strain rates. Such an increase is usually associated with the multiplication of dislocations in the phonon friction mode, which slows with temperature. However, the effect of temperature on the structure of the shock wave and the yield strength of metal

Isotropic soft magneto-rheological elastomers (s-MRE) are polymer-based composites where magnetically soft particles are randomly distributed in the elastomer matrix. Under a magnetic field, a strong modulus magnetic stiffening effect and a magnetostriction performance is exhibited for isotropic s-MRE, offering a wide application potential in vibration control, soft robotics and haptic displays. In

The cold spray (CS) process has been demonstrated to be an attractive additive manufacturing technology for the development of freeforms and coatings from temperature-sensitive materials. However, owing to the lower bonding strength and inhomogeneous residual stress field distribution, the fatigue performance of CS deposition cannot satisfy the requirements of numerous engineering conditions. This

We build a crystal plasticity finite element framework to investigate slip localisation and fatigue-creep behaviour at the cooling holes of single crystal Nickel (Ni) based components under cyclic thermomechanical loading. The total slip rate is decomposed into a thermally activated dislocation glide rate which dominates at moderate/low temperatures (T) and/or high stresses, and a climb rate which

The microstructures, mechanical properties, and deformation substructures of gradient Mo0.3NiCoCr medium-entropy alloys (MEAs) with very coarse grain size created by pre-torsion have been investigated. The strength of MEAs increases with the increase of torsion angle, while the tensile elongation nearly remains the same, suggesting the enhanced strength-ductility synergy. The initial dislocation density

Cross-slip is a thermally activated process by which screw dislocation changes its glide plane to another slip plane sharing the same Burgers vector. The rate at which this process happens is determined by a Boltzmann type expression that is a function of the screw segment length and the stress acting on the dislocation. In continuum dislocation dynamics (CDD), the information regarding the length

This article addresses the problem of the multiscale constitutive representation of the multiaxial inelastic behavior of elastomeric particulate composites. A fully three-dimensional model is proposed within a micromechanical treatment to describe the multiaxial inelastic response in relation to the reinforcement mechanisms. A network decomposition based on the tube confinement theory is used to consider

Additive manufacturing has gained increasing interest to fabricate metal matrix composites. Particle agglomeration remains a critical challenge and can severely compromise the mechanical properties, in particular tensile ductility. Here we investigated and utilized laser powder-bed-fusion (L-PBF) to uniformly disperse particles in metal matrices, taking advantages of particle flow dynamics during melting

A fully analytical framework of yield criterion is constructed under non-associated flow rule to describe asymmetric yielding and anisotropic hardening based on the concept of shape functions. For the yield function, eight parameters are identified by employing the corresponding tensile and compressive hardening functions along the four directions, i.e., uniaxial directions along 0°, 45°, 90° in relation

Zirconium alloys are widely used as the fuel cladding material in pressurized water reactors, accumulating a significant population of defects and dislocations from exposure to neutrons. We present and interpret synchrotron microbeam X-ray diffraction measurements of proton-irradiated Zircaloy-4, where we identify a transient peak and the subsequent saturation of dislocation density as a function of

Constitutive relation remains one of the most important, yet fundamental challenges in the study of granular materials. Instead of using closed-form phenomenological models or numerical multiscale modelling, machine learning has emerged as an alternative paradigm to revolutionise the constitutive modelling of granular materials. However, deep neural networks (DNNs) require massive training data and

A novel experimental setup is presented that allows for precise control of thermal and mechanical loads, and simultaneous monitoring of the temperature and the full-field deformation of small SMA structures that undergo phase transformations. The facility is used to conduct two experiments in which NiTi tubes are taken through a temperature cycle under constant load that leads to phase transformations

Superalloy ultrathin sheets have high strength, outstanding oxidation resistance, corrosion resistance and fatigue performance, and its thin-walled components occupy a considerable proportion in aeroengines. In the microforming process of aeroengine thin-walled components, the superalloy ultrathin sheet is often deformed under complex loading states and shows obvious springback. However, the forming

This paper presents a multi-level viscoplastic self-consistent (VPSC) model for correlated structures (CS-VPSC). A polycrystalline aggregate response is homogenized over inclusions, which are linearized using the generalized affine scheme. Response of the inclusions is that of either a single grain or a correlated structure of multiple single crystals. The single crystal response is a strain rate adjusted