Stress Σf Research Articles

Comparative Analysis of Bursting Pressure Prediction Methods for Steam Generator Tube With Volume Defect

Abstract This paper compares the difference and accuracy of bursting pressure prediction based on the flow stress σf prediction method, plastic collapse prediction method, and ductile damage model prediction method in Inconel 690 steam generator tube (SGT) with volume defect. The tensile and smooth tube bursting tests determine the parameters required for the three prediction methods. The three methods predict the bursting pressures for four deep volume defects in SGT. The results are compared and analyzed with the experimental data. The results show that the ductile damage model prediction method is the best to predict the SGT bursting pressure error with volume defects simulating the structure's deformation and damage failure process.

Influence of particle network characteristics on the dynamic rheological properties of red lentil puree fractions

The complex cellular structure of plant-based purees has a great impact on their rheological properties, as affected by particle-related factors such as their shape, size and concentration. The aim of this study was to unravel the impact of particles characteristics on viscoelastic properties of fractions from a red lentil puree containing high contents of starch and protein. Four particle fractions were separated from the puree: cell fragments (CF), single cells (SC), cell clusters (CC), and a mix of all particles (MP). Their composition, structural properties, stability upon dilution and dynamic rheological properties after reconstitution at three pulp contents were investigated. CF was mostly made of aggregated cell fragments containing extracellular starch, SC was characterized by dispersed parenchyma cells filled with intracellular starch, and CC of cell clusters containing some intracellular starch. The viscoelastic properties seemed driven by starch location, as SC and CC had higher power law constant values (K') and flow stress (σf), with lower yield strain (γy) than CF: extracellular starch could form a continuous entangled network, entrapping particles and decreasing the gel strength. CF was also the most stable to dilution, which emphasized the role of extracellular starch on networks cohesion. K' and σf were higher in CC than in SC, probably because of the roughness of cell clusters assessed by their low solidity values, as opposed with single cells of smoother surface. Such work on pulse puree particle networks helped to understand the mechanisms involved in a complex structured food system rich in starch and protein.

Microstructure and Superelasticity of Cu–Sn Shape-Memory Microwires by Glass-Coated Melt Spinning

Cu–Sn shape-memory microw ires were fabricated by a glass-coated melt spinning method. Effects of Sn content on the microstructure and mechanical properties of microwires were investigated. The phase transforms from martensite to austenite with an increase in Sn from 14.0 atomic percent (at.%) to 16.5 at.%. When the Sn content exceeds 16.5 at.%, a highly ordered intermetallic phase, δ, formed. The fracture stress (σf) and the critical stress for martensitic transformation (σMs) increases with an increase in Sn content. The mechanical properties as well as the superelasticity were greatly improved by a high cooling rate in the glass-coated melt spinning method. A bamboo-grained structure was formed in the Cu–Sn microwire with a Sn content of 16 at.% by annealing at 750 °C for 5 h before quenching in water. The results indicate that two opposite strategies of refining the grain size to the micrometer level, or increasing the grain size to a one dimensional size of specimen, e.g., the diameter of the wire, are both effective in improving the superelasticity of the Cu–Sn alloy.

Numerical and Experimental Study of a Lattice Structure for Orthopedic Applications.

Prosthetic reconstructions provide anatomical reconstruction to replace bones and joints. However, these operations have a high number of short- and long-term complications. One of the main problems in surgery is that the implant remains in the body after the operation. The solution to this problem is to use biomaterial for the implant, but biomaterial does not have the required strength characteristics. The implant must also have a mesh-like structure so that the bone can grow into the implant. The additive manufacturing process is ideal for the production of such a structure. The study deals with the correlation between different prosthetic structures, namely, the relationship between geometry, mechanical properties and biological additivity. The main challenge is to design an endoprosthesis that will mimic the geometric structure of bone and also meet the conditions of strength, hardness and stiffness. In order to match the above factors, it is necessary to develop appropriate algorithms. The main objective of this study is to augment the algorithm to ensure minimum structural weight without changing the strength characteristics of the lattice endoprosthesis of long bones. The iterative augmentation process of the algorithm was implemented by removing low-loaded ribs. A low-loaded rib is a rib with a maximum stress that is less than the threshold stress. Values within the range (10, 13, 15, 16, 17, 18, 19 and 20 MPa) were taken as the threshold stress. The supplement to the algorithm was applied to the initial structure and the designed structure at threshold stresses σf = 10, 13, 15, 16, 17, 18, 19 and 20 MPa. A Pareto diagram for maximum stress and the number of ribs is plotted for all cases of the design: original, engineered and lightened structures. The most optimal was the designed "lightweight" structure under the condition σf = 17 MPa. The maximum stress was 147.48 MPa, and the number of ribs was 741. Specimens were manufactured using additive manufacturing and then tested for four-point bending.

Properties at Low Temperatures of Asphalt Mixes Containing High Content of Multi-recycled RAP

Abstract The reuse of reclaimed asphalt pavement (RAP) in the production of new asphalt mixes is a valuable environmental approach. Likewise, new lower-temperature manufacturing processes (warm) of asphalt mixes have an impact in the reduced fuel consumption and gas emissions during production. In 2014, the French National Research Agency launched the French national project “Innovation for Materials and Processes for Improving the Multi-Recycling of Mixtures” (IMPROVMURE). The main objective of the IMPROVMURE project was to determine, over the life cycle of pavement materials, the impact of successive recycling at different rates and for different manufacturing techniques (hot and warm processes). To estimate the thermomechanical properties of multi-recycled asphalt mixes, a characterization of behavior by coupling the thermal and mechanical effects at low temperatures was carried out. This paper presents the thermal stress restrained specimen test (TSRST) results of six asphalt mix types, three hot asphalt mixes, and three half-warm asphalt mixes using a foamed binder. Some of these asphalt mixes were manufactured with a content up to 70 % RAP and 70 % multi-recycled RAP. TSRST were performed on cylindrical specimens at the University of Lyon/école nationale des travaux publics de l’état (ENTPE). The failure temperature (TF), failure stress (σF), and failure radial deformation (εrF) were evaluated to analyze and compare the behavior of mixes at low temperature. The influences of RAP content, recycling cycle, air void content, and manufacturing process were studied, and the air void content showed an effect inversely proportional to the failure stress.

Optimized low-cycle fatigue behavior and fracture characteristics of Ti–6Al–4V alloy by Fe microalloying

In the present work, low cycle fatigue (LCF) behavior and fracture characteristic of Ti–6Al–4V-0.55Fe alloy with bimodal microstructure, consisted of equiaxed primary α (αp), lamellar α (αl) and β matrix, are systematically investigated at room temperature. Results indicate that Ti–6Al–4V-0.55Fe alloy mainly exhibits a continuous softening behavior both at high and low strain amplitudes, due to the interaction of back stress(σb) and friction stress(σf) mainly related to the plastic deformation heterogeneity and precipitates shearing, respectively. Compared with Ti–6Al–4V alloy, LCF life of Ti–6Al–4V-0.55Fe is similar at high strain amplitudes (Δεt/2 > 1.0%), while much higher at low strain amplitudes (Δεt/2 < 1.0%), which could be attributed to the extra resistance to dislocation movement and crack propagation produced by Fe microalloying. The fractography shows remarkably different characteristics for these imposed strain amplitudes. At low strain amplitude, there is only one crack initiation site caused by dislocations pile-ups and stress concentration on the specimen surface, accompanied with narrower fatigue striation, while more cracks initiated on the surface with wider fatigue striation due to strain accumulation at high strain amplitudes.

Fatigue failure of ball joint heads connected to the weight holder mechanism in railway applications

The premature causes of failure of ball joint heads attached to the weight bearing bar used on high speed trains, which were continuously under traction, have been studied, with an average load of 47.5 kN plus a cyclical load of ± 7.5 kN. Ball joint heads made of C45 (AISI 1045) carbon steel show a pearlite microstructure (80–90 %) with ferrite surrounding the prior-austenite grain boundaries. Two different external elliptical-shaped fatigue cracks of 14.5 mm and 7.7 mm nucleated in opposite positions on the cylindrical surface of the threaded shank prior to catastrophic cleavage failure. The Griffith equation applied in this study gave a value of 37 MPa for the fracture stress (σf) produced by the largest crack, which multiplied by the section of the thread is equivalent to a load of 37 kN, similar to the applied service load. In addition, the critical stress intensity factor (KIc) calculation yielded a value of 8.8 MPa m1/2, this lower KIc value was determined to be responsible for the large fatigue crack produced and the cleavage fracture causing the C45 carbon steel bolt joint failure. The pearlite/ferrite microstructure contributed to crack growth, since this type of microstructure in high carbon steels has lower strength and lower toughness than a tempered martensite microstructure. Using Paris equation, the cycles to failure were 1.5 × 105, which in service lifetime was an approximated 6 × 106 km for the piece to finally fail.

Effect of Zinc on the Tensile Properties, Microstructure and characteristics in Aluminum Alloys

The existing work characterizes the consequence of Zinc increase of the precise structure, thermal and mechanical characteristic of Aluminum by supplement 60% Zinc and 10 % Zinc to fine Aluminum alloy to gained Zinc-40Aluminium and Zinc-90Aluminium. The study presented that the superplasticity of Zinc-90Aluminium is reduced compared with Zinc-40Aluminium. The strain rate (SR; .) and temperature (T) are having extremely influence on tensile figure. Too (SR; .) and (T) donate excellent Young's modulus (Y), ultimate tensile stress (UTS), yield stress (σy), and fracture strength (breaking strength) σf associated with the exponent rule σ =Ce•m; where C is a fixed number and m is the strain average sensitivity index; while strain rate and temperature decrease fracture strain (ef ). The tensile figures are (T) and (SR;  .) dependence. Stress-strain characteristics of Zinc-40Aluminium and Zinc-90Aluminium alloys were investigated at various strain rates (SR, e•) from 5.0×10-4 to 6.4×10-3 s-1 and deformation temperatures from 298 to 393 K. In case of Zinc-90Aluminium; it has higher ultimate tensile stress (UTS) i.e. Zinc-40Aluminium is more in elongation (ductility) than Zinc-90Aluminium. A common decrease of strain eT with (SR;  .) is characterized by the equation eT =Aexp(-λe•m); A and λ are constant. The results depend on variation precise structure. The Zinc supplement from 10% to40% refines the precise structure, enhancing the mechanical properties, and form increase the ductility.

Chitin-Based Double-Network Hydrogel as Potential Superficial Soft-Tissue-Repairing Materials.

Chitin is a biopolymer, which has been proven to be a biomedical material candidate, yet the weak mechanical properties seriously limit their potentials. In this work, a chitin-based double-network (DN) hydrogel has been designed as a potential superficial repairing material. The hydrogel was synthesized through a double-network (DN) strategy composing hybrid regenerated chitin nanofiber (RCN)-poly (ethylene glycol diglycidyl ether) (PEGDE) as the first network and polyacrylamide (PAAm) as the second network. The hybrid RCN-PEGDE/PAAm DN hydrogel was strong and tough, possessing Young's modulus (elasticity) E 0.097 ± 0.020 MPa, fracture stress σf 0.449 ± 0.025 MPa, and work of fracture Wf 5.75 ± 0.35 MJ·m-3. The obtained DN hydrogel was strong enough for surgical requirements in the usage of soft tissue scaffolds. In addition, chitin endowed the DN hydrogel with good bacterial resistance and accelerated fibroblast proliferation, which increased the NIH3T3 cell number by nearly five times within 3 days. Subcutaneous implantation studies showed that the DN hydrogel did not induce inflammation after 4 weeks, suggesting a good biosafety in vivo. These results indicated that the hybrid RCN-PEGDE/PAAm DN hydrogel had great prospect as a rapid soft-tissue-repairing material.

Experimental study of the CTBN effect on mechanical properties and mode I and II fracture toughness of a new epoxy resin

Due to the high strength and adhesiveness of epoxies, these materials are widely used in various industries such as aerospace. But because of their inherent brittleness and poor fracture toughness, they do not have enough resistance against crack propagation. In adhesive joints, maximum stresses near the ends of the overlaps resulted in premature failure of the joints. In this study, for toughening the epoxy, carboxyl-terminated butadiene acrylonitrile (CTBN) as a liquid rubber was used. Blends of a new epoxy resin (R510) and the CTBN in several weight fractions were produced and characterized. In this article, four tests have been done to find the mechanical properties and mode I and II fracture toughness of the adhesives. The tensile and shear tests were performed to achieve Young’s modulus (E), maximum tensile stress (σf), shear modulus (G), maximum shear stress (τf) and Poisson’s ratio (ν) of the adhesives. Also, the double-cantilever beam (DCB) and end-notched flexure (ENF) tests were used to obtain the mode I fracture toughness (GIc) and mode II fracture toughness (GIIc), respectively. The results from each of the DCB and the ENF tests were analyzed by three different methods and compared. Results showed that by adding CTBN to epoxy, E, G, ν, σf and τf are reduced, but toughness, the resistance to crack growth and as a result, the GIc and GIIc increased efficiently. These data can be used to predict the adhesive joint strength and simulating the damage initiation and its evolution until failure with cohesive zone modeling (CZM).

Microstructure, mechanical and thermo-physical properties of CVD TiCxN1-x coatings on cemented carbide substrates grown with C2H6 as C feeding precursor

The established industrial processes used for the growth of TiCxN1-x coatings by chemical vapor deposition (CVD) suffer from substantial limitations, either in regard of brittle phase formation or restriction in the C/(C + N) ratio. Using the alternative C precursor C2H6 allows to overcome these issues. Thus, within this work, the microstructure, phase composition, micro-mechanical and thermo-physical properties of CVD TiCxN1-x coatings grown with C2H6 were investigated. Through adjustment of the C2H6 and N2 flow in the feed gas, the C/(C + N) ratio in the coatings was varied between pure TiN and TiC0.80N0.20. All coatings are characterized by a single-phase face centered cubic structure. The 〈110〉 fiber texture present in all coatings becomes more pronounced with increasing C content. None of the investigated coatings showed thermal cracks on the surface. The thermal conductivity decreases with addition of C from 45 ± 5 W/mK in TiN to 32 ± 3 W/mK in all ternary TiCxN1-x coatings. TiC0.47N0.53 exhibits the highest hardness (30.0 ± 1.4 GPa), while TiC0.63N0.36 turned out as the stiffest coating with a Young's modulus of 576 ± 23 GPa. The fracture stress σF and toughness KIC are superior in coatings with moderate C and N content, with TiC0.63N0.37 being the strongest (σF = 7.7 ± 0.4 GPa) and TiC0.47N0.53 (KIC = 4.4 ± 0.3 MPa m1/2) the toughest within this series. Coatings with moderate to high C content were found to exhibit a microstructure provoking a lower thermal conductivity and improved mechanical properties compared to those with a low C/(C + N) ratio.

Effect of Multiple Tempering on Mechanical Properties and Microstructure of Ledeburitic Tool Steel AISI D3

The effects of multiple tempering on the mechanical properties and microstructure of ledeburitic tool steel AISI D3 were investigated. Austenized samples at: 940 °C and 970 °C were used The subsequent tempering was carried out in three stages with the same temperatures: 250-350-450-550 ° C; for 1 hr. The microstructure was revealed at optical (OM) and electronic (SEM) levels and then X-ray diffraction analysis (DRX) was made along with an X-ray scatter spectrometry (EDS) test. It was found that the yield stress (σf), the maximum tensile strength (σr) and ductility (ɛ) decrease with the number of temperings. The microstructures, in the three stages, show primary, massive and small carbides of type M7C3, and Cr7C3, accompanied by precipitated fine carbides of the same type, with the presence of the phases: Fe3C, Cr0.03 Fe0.97 and residual austenite (γr), the latter phase is minimized with the third temper. These precipitates occur at each stage of tempering simultaneously or as the temperature increases. The variation of these properties is closely related to the microstructure obtained.

Bond between CFRP rod panels and concrete using cementitious mortar

Carbon-FRP rod panels (CRPs), generated from small diameter rods mounted on a fiberglass mesh, are becoming a viable retrofit option. The gaps between rods enable full encapsulation by adhesive, thereby enhancing bond to existing concrete members, compared to flat plates. Existing studies focused on epoxy adhesive. In this study, 44 notched-beam bond tests, were carried out to investigate the effectiveness of cementitious mortar in bonding CRP to concrete and to examine the effects of a number of material and geometric parameters, comparing CRP to flat plates and mortar to epoxy. Results showed that the mortar was able to achieve a comparable ultimate load (Pult.), 86% that of epoxy, and a much more ductile failure by gradual rod slippage from the mortar. Compared to an equivalent CFRP plate, Pult. of CRP was 1.17 and 7 times, respectively, for epoxy and cementitious mortar. Brittle debonding failure dominated in CRP with epoxy and in CFRP plate with both epoxy and mortar. Pult was found to vary linearly with the bond length of CRP, up to a development length of 125 mm. A value of 460 kN/m can be assumed for bond strength. Rod axial stress (σf) increased by 42%, when CRP panel-to-concrete width (bf /bc) ratio increased from 0.25 to 0.5; decreased linearly by 13% when rod spacing-to-diameter (S/D) ratio increased from 3 to 8; decreased by 76% when rod diameter D increased from 2 to 4 mm. Sand coating the smooth rod resulted in a 45% increase in σf of the 4 mm rods but not the 2 mm rods, although failure shifted from gradual slippage to sudden debonding.

Linking macroscopic failure with micromechanical processes in layered rocks: How layer orientation and roughness control macroscopic behavior

To constrain the impact of preexisting mechanical weaknesses on strain localization culminating in macroscopic shear failure, we simulate triaxial compression of layered sedimentary rock using three-dimensional discrete element method simulations. We develop a novel particle packing technique that builds layered rocks with preexisting weaknesses of varying orientations, roughness, and surface area available for slip. We quantify how the geomechanical behavior, characterized by internal friction coefficient, μ0, and failure strength, σF, vary as a function of layer orientation, θ, interface roughness, and total interface area. Failure of the simulated sedimentary rocks mirrors key observations from laboratory experiments on layered sedimentary rock, including minima σF and μ0 for layers oriented at 30° with respect to the maximum compressive stress, σ1, and maxima σF and μ0 for layers oriented near 0° and 90° to σ1. The largest changes in σF (66%) and μ0 (20%) occur in models with the smoothest interfaces and largest interface area. Within the parameter space tested, layer orientation exerts the most significant impact on σF and μ0. These simulations allow directly linking micromechanical processes observed within the models to macroscopic failure behavior. The spatial distributions of nucleating microfractures, and the rate and degree of strain localization onto preexisting weaknesses, rather than the host rock, are systematically linked to the distribution of failure strengths. Preexisting weakness orientation more strongly controls the degree and rate of strain localization than the imposed confining stress within the explored parameter space. Using the upper and lower limits of μ0 and σF obtained from the models, estimates of the Coulomb shear stress required for failure of intact rock within the upper seismogenic zone (7 km) indicates that a rotation of 30° of σ1 relative to the weakness orientation may reduce the shear stress required for failure by up to 100 MPa.

The admissible range of notch root radius for applying the singular stress field to its fracture analysis

In this study, the problem of “what is the critical value of notch root radius ρmax below which the fracture load of the notch with ρ≠0 can be evaluated by using the singular stress field for a sharp notch” is investigated analytically. Based on the existing fracture criteria, the ultimate loading stresses σf and σF are respectively calculated by using numerical analysis called body force method for the blunt notch and by using the singular stress field for the corresponding sharp notch. By comparing σf with σF, the admissible maximum notch root radius ρmax is investigated. Based on the investigation, it is found that when the notch root radius ρ is approximately 0.4 times smaller than d0m = 2/π(KIC/σC)2, the predictive error of the fracture load for the blunt notch(ρ≠0) by using the singular stress field for sharp notch (ρ=0) could be within ±5%. Here, the notch depth should be taken as large as t>4d0m.

Mechanism of Decrease in Impact Toughness in a Low-Carbon MnCrMoNiCu Plate Steel with Increasing Austenitizing Temperature

In order to reveal how microscopic factors affect the toughness and the occurrence of cleavage fracture of a low-carbon MnCrMoNiCu alloyed steel, a series of thermal treatments was performed on the steel employing a thermomechanical simulator. These involved reheating samples at different temperatures (950-1250 °C), producing different prior austenite sizes, followed by a continuous cooling transformation process. The Charpy V-notch toughness was determined, and the effect of austenite grain size on the ductile-to-brittle transition temperatures of the steel was investigated. The microstructural evolution on the austenite sizes was studied, fracture features were characterized, the critical event for cleavage fracture was identified, and the local cleavage fracture stress σf was calculated. The impact toughness decreased as the austenitizing temperature increased. A quantitative relationship between σf and the size of the initial cleavage fracture facet (microcrack nucleus) af in the lathy martensite + bainite microstructure has been developed.

Microstructural Evolution and Ductile-to-Brittle Transition in a Low-Carbon MnCrMoNiCu Heavy Plate Steel

Low carbon MnCrMoNiCu alloyed steels are typically used to produce highly ductile thick plates for offshore structures and bulk shipbuilding. The current study revealed how microscopic factors affect the toughness and the occurrence of cleavage fracture of the steel. In this regard, a series of thermal treatments was performed on the test steel by employing a thermomechanical simulator. These involved reheating samples at different temperatures (1168 K to 1623 K (895 °C to 1350 °C)) producing different prior austenite grain sizes, followed by a continuous cooling transformation process. The Charpy V notch (CVN) toughness was determined, and the effect of the austenite grain size on the ductile–brittle transition-temperatures of the steel was investigated. The microstructural evolution of the austenite grain sizes was studied, fracture features were characterized, the critical event for cleavage fracture was identified, and the local cleavage fracture stress σf was calculated. The CVN toughness and σf were maximized in the steel which was reheated at 1273 K (1000 °C) and containing refined lathlike bainite.

Structural, magnetic and mechanical properties of Nd6.8Fe63.3Nb4.0Co1.3Cr1.1Zr0.9B22.6 nanocrystalline hard magnet

Microstructural, magnetic and mechanical properties of Nd6.8Fe63.3Nb4.0Co1.3Cr1.1Zr0.9B22.6 nanocrystalline hard magnets produced by rapid solidification technique and subsequent thermo-magnetic annealing have been investigated in this study. X-ray diffraction analysis revealed that the as-cast Nd6.8Fe63.3Nb4.0Co1.3Cr1.1Zr0.9B22.6 magnet has 60% Nd2Fe14B, 16% α-Fe, 9% Fe3B and 15% amorphous phases, whereby, Nd2Fe14B being the majority phase. Thermomagnetic annealing induces a complete crystallization of Nd2Fe14B, α-Fe, Fe3B and amorphous phases and establishes ideal volume fractions between phases leading to improvement in magnetic properties. Scanning and transmission electron microscopy show nano-scaled hard Nd2Fe14B grains surrounded with soft α-Fe and Fe3B grains. The Nd6.8Fe63.3Nb4.0Co1.3Cr1.1Zr0.9B22.6 magnet annealed at 993 K for 15 min shows values of coercivity iHc, remanence Br and maximum energy product (BH)max up to 861 kA/m, 0.68 T and 81.9 kJ/m3, respectively. Compressional stress strain measurements elucidated that mechanical properties of alloys are affected by the morphology of phases as well as crystal structure. As-cast Nd6.8Fe63.3Nb4.0Co1.3Cr1.1Zr0.9B22.6 magnet demonstrates the hardness (Hv) of 960 ± 20 and compressive stress (σf) of 1270 ± 10 MPa, which tend to decrease by thermo-magnetic annealing process.

Geomechanical and Hydrodynamic Fields in Producing Formation in the Vicinity of Well with Regard to Rock Mass Permeability-Effective Stress Relationship

The nonlinear model is developed to describe geomechanical and hydrodynamic fields in the vicinity of a vertical well in a fluid-saturated formation for the case when the permeability k depends on the effective stress σf by the exponential law. The analytical solutions are obtained for the porous-elastic and porous-elastoplastic modes of deformation of the well vicinity, based on which the change in the pressure and rate of flow under the variation of parameters characterizing the dependence k(σf) is analyzed. It is found that the rate of flow exponentially decreases with an increasing horizontal stress of the external field; the permeability of the irreversible strain zone around the well decreases with the distance from the well boundary. The test scheme is proposed for permeability of samples with the center hole under side loading, and the experimental data interpretation procedure is put forward, which enables finding the empirical dependence k(σf).

Mechanical properties of gelatin/polyacrylamide/graphene oxide nanocomposite double-network hydrogels

Gelatin/polyacrylamide/graphene oxide nanocomposite double-network hydrogels (Gelatin/PAAm/GO NC-DN gels) were prepared by in situ free radical polymerization. Their structure and properties were systematically characterized by X-ray diffraction (XRD), Raman spectroscopy, swelling experiments, scanning electron microscopy (SEM) and tensile tests. The results reveal that the GO nanosheets are significantly exfoliated in the gel matrix, serving as multi-functional cross-linkers in the NC-DN gels. At an optimal condition, Gelatin/PAAm/GO NC-DN gel demonstrates an excellent mechanical properties of an elastic modulus (E) of 187.3 kPa, a fractured stress (σf) of 0.324 MPa), a fractured strain (εf) of 45.5 mm/mm and a fractured energy (W) of 10.18 MJ/m3. More interestingly, the gels show a large hysteresis loop, softening phenomenon and self-recovery properties. This work deepens the understandings of the effect of nanomaterials on the mechanical properties of DN gels.