Unidirectional Loading Research Articles

Estimating response of structures to earthquake-induced tsunami: A simple approach per unidirectional analysis

The orientation of a structure with respect to the direction of propagation of tsunami wave may often be arbitrary. As such, it may be convenient to consider the tsunami wave as a combination of two orthogonal pair. The response of structures may then be computed to the simultaneous action of two components (bidirectional) covering multiple incidence angles. However, analysis of structures in three-dimension under two orthogonal components is a daunting exercise for routine design. Against this backdrop, beginning with the validation of the simulation of tsunami against real records, a detailed scrutiny of the response of simple building frames to tsunami is made over a range of orientations per both unidirectional and bidirectional analyses. This indicates the sensitivity of response over orientations and suggests that the maximum response to a bidirectional tsunami attack can be closely estimated by unidirectional analysis at appropriate orientations. This reveals the existence of the most intense orientations in which the response to unidirectional loading may approximately represent the maximum response to bidirectional loading over all orientations. Observing statistically significant positive correlation of tsunami potential (Pd) and peak destructive potential (Id) to the response to unidirectional tsunami attacks, these pure tsunami parameters are selected as suitable intensity measures (IM). Analytical (as well as graphical through standard Mohr’s circle) expressions are then derived for the orientations in which such IM can assume the maximum. It is shown that the unidirectional analysis conducted in these orientations can closely estimate the maximum response to bidirectional attacks out of all possible orientations for single story and multistorey building frames. Hence, the straightforward unidirectional analysis in the most intense orientations may be adopted for design of coastal structures.

Behaviour of square plate anchors under unidirectional and combined loadings in clay

This paper presents a comprehensive 3D small strain finite element investigation into the behaviours of square anchors under unidirectional or V-H-M combined loadings (normal, tangential and rotational forces/moment). Selected numerical results are first compared with existing studies for validation. Then, a large quantity of parametric study on anchor embedment and inclinations are conducted. Under unidirectional loading, loading rate and anchor velocity are found to be non-coaxial when anchor embedment ratio is less than 1, invalidating the commonly believed coaxiality. Under combined loading, square anchors can be classified into deep, shallow, and very shallow anchors, with threshold embedment ratios approximately at 1.5 and 0.6. Deep anchor failure envelopes are independent of embedment and inclination, featuring symmetric and concentric equal-M cross-sections. Shallow anchor failure envelopes retain concentricity but may lose symmetry. For very shallow anchors, the concentricity can be further broken. The widely employed expression for quantifying plate anchor failure envelopes is found to overestimate anchor capacity as M increases, and it cannot capture the asymmetricity and concentricity for shallow or very shallow anchors failure envelopes. To overcome these limitations, alternative expressions are proposed and validated against finite element data.

Phase-field based shape optimization of uni- and multiaxially loaded nature-inspired porous structures while maintaining characteristic properties

Triply periodic minimal surfaces (TPMS) are highly versatile porous formations that can be defined by formulas. Computationally based, load-specific shape optimization enables tailoring these structures for their respective application areas and thereby enhance their potential. In this investigation, individual sheet-based gyroid structures with varying porosities are specifically optimized with respect to their stiffness. A modified phase-field method is employed to establish a simulation framework for the shape optimization process. Despite constant volume and the preservation of the periodicity of the unit cells, volume redistribution occurs through displacement of the interfaces. The phase-field-based optimization process is detailed using unidirectional loading on three gyroidal unit cells with porosities of 75 %, 80 %, and 85 %. Subsequently, the gyroidal unit cell with a porosity of 85 % is shape-optimized under multidirectional loading. A subsequent experimental validation of the unidirectionally loaded cells confirms that the shape-optimized structures exhibit, on average, higher stiffness than the non-optimized structures. The highest increase of 40 % in effective modulus is achieved with the gyroid structure having a porosity of 75 %, while maintaining minimal alteration to the surface-to-volume ratio and preserving periodicity. Additionally, the experimental data show that the optimization process resulted in a shift in the linear elasticity and plasticity range. In summary, the phase-field method proves to be a valid optimization technique for complex porous structures, allowing the preservation of characteristic properties.

Seismic response of rocking bridge systems under three-dimensional ground motions

Compared to theoretical models, finite element methods provide greater versatility for dynamic response analyses of rocking bridges, especially when considering the influences of various nonlinear boundary conditions. A finite element modeling method based on fiber section elements for three-dimensional seismic analyses of rocking bridges is developed in this paper. This method solves the problem of energy dissipation and stiffness determination of the rocking interface. Based on the proposed modeling method, considering nonlinear boundary conditions (such as abutment-soil interaction, impact effect, and pile-soil interaction), the seismic responses of rocking bridges, including free rocking, prestressed rocking and prestressed rocking with dampers, under the excitation of three-dimensional ground motions are analyzed. The results show that: after reasonable design, the prestressed rocking bridge with dampers exhibits similar seismic responses to the cast-in-place bridge, and maintains a good self-centering ability. The responses of all the rocking bridges under bi-directional loading are greater than those under unidirectional loading. In contrast, vertical ground motion's influence on the response of the rocking bridges is minimal. Ignoring the pile-soil interaction significantly underestimates the seismic demand of the evaluated bridges, especially the free rocking bridge and rocking bridge with prestressed tendons only.

Mechanical analysis of polyester resin using digital image correlation and finite element method

The primary objective of this study is to perform a comprehensive mechanical analysis of unsaturated polyester (UP) resin under unidirectional tensile loading. The Digital Image Correlation (DIC) technique was employed to accurately determine the mechanical properties of the material, with full-field strain measurements used to extract both transverse and longitudinal strains through virtual extensometers. This approach facilitated the precise calculation of the Poisson’s ratio of the UP resin. The results obtained via DIC demonstrated strong correlation with the experimental data obtained through the machine’s control software, particularly in capturing vertical displacement and longitudinal strain with high precision. The Poisson’s ratio was found to be 0.46. To further validate the DIC findings, Finite Element Analysis (FEA) was conducted. The FEA results aligned closely with the experimental data, confirming the reliability and accuracy of the DIC method in this context. The values of Young’s modulus determined from experimental tests and FEA data were 3620.02 MPa and 3598 MPa, respectively, with a percentage error of only 0.61%.

Experimental study on mechanical properties of pin-trunnion connection nodes of temporary steel brackets for elevated bridges

Currently, the pin connection test exists mainly for unidirectional force loading, while the pin connection of a temporary steel bracket applied to elevated bridges is for bi-directional force. The damage mechanism of the pin connection with bi-directional force is not yet fully understood in research. The effect of the loading direction, single-hole plate end distance and unilateral width ratio a/b, ear plate thickness ratio t1/2 t2, and ear plate shape on the mechanical properties of the pin connection need to be considered. In this study, destructive static loading tests were conducted on eight groups of double-hole pin connections, and the damage mode, bearing capacity, deformation, and strain of the pin connections were determined. The results show that the thickness of the trunnion plate primarily controls the damage mode of the pinned connection and the ratio is smaller for single-trunnion plate damage, which can achieve larger bearing capacity and deformation. The ratio of the end distance of the monocore plate to the width of the single side primarily controls the damage location of the monocore plate, and the ratio varies from large to small, gradually causing tensile damage to the side section, end cleavage damage, and end shear damage. The loading direction has a minor effect on the mechanical properties of the pin connection; however, the tensile deformation is significantly larger than the compressive deformation. By chamfering, the M shape is properly adjusted to optimize the shape of the double trunnion plate, which does not reduce the load-carrying capacity and deformation of the pin connection and can reduce the amount of steel used by 10 %. A comparative analysis of the change in the ear-plate shape before and after the open ear-plate test, determination of the cross-sectional damage location and effective calculation distance b1, and improvement and derivation of a practical method for calculating the load-carrying capacity for engineering are performed, at the same time, it can be applied to projects of different spans, which can greatly improve construction efficiency and reduce labor costs.

Seismic Design and Ductility Evaluation of Thin-Walled Stiffened Steel Square Box Columns

This paper investigates the seismic performance of thin-walled stiffened steel square box columns, modeling bridge piers subjected to unidirectional cyclic lateral loading with a constant axial load, focusing on local, global, and local-global interactive buckling phenomena. Initially, the finite element model was validated against existing experimental results. The study further explored the degradation in strength and ductility of both thin-walled and compact columns under cyclic loading. Thin-walled, stiffened steel square box columns exhibited buckling near the base, forming a half-sine wave shape. The research also addresses discrepancies from different material models used to analyze steel tubular bridge piers. Analysis using a modified two-surface plasticity model (2SM) yielded results closer to experimental data than a multi-linear kinematic hardening model, particularly for compact sections. The 2SM, which accounts for cycling within the yield plateau and strain hardening regime, demonstrated enhanced accuracy over the multi-linear kinematic hardening model. Additionally, a parametric study was conducted to assess the impact of key design parameters—such as width-to-thickness ratio (Rf), column slenderness ratio (λ), and magnitude of axial load (P/Py)—on the performance of thin-walled stiffened steel square box columns. Design equations were then developed to predict the strength and ductility of bridge piers. These equations closely matched experimental results, achieving an accuracy of 95% for ultimate strength and 97% for ductility.

Modeling of residual stiffness phenomenon in modified Iwan model of bolted joints and its application

Bolted joints have been widely used in various mechanical structures. Due to the presence of contact interfaces, the joints exhibit complex nonlinear behavior under dynamic loading. Effective prediction of the dynamic response of bolted structures requires the construction of appropriate dynamic models. This paper proposes a modified Iwan model which gives a more comprehensive description of joints than the previous Iwan models, especially for the phenomenon of residual stiffness in macro slip. The equations of the model's backbone curve, hysteresis curve, and energy dissipation are derived. The parameter identification procedure is also provided. Subsequently, connection elements based on the modified Iwan model are integrated into a single bolted joint and a thin-walled cylinder containing multiple bolted joints, the responses under quasi-static unidirectional loading, quasi-static cyclic loading and constant-frequency excitation are investigated. The physical interpretation of the parameters in the model is discussed, thus explaining the relationship between the bolted joint's physical parameters and some important variables. The results indicate that the model can effectively characterize the nonlinear mechanical behavior of the bolted joint for both micro and macro slip regime, with significant improvement in computational efficiency.

Cross-sectional size, shape, and estimated strength of the tibia, fibula and second metatarsal in female collegiate-level cross-country runners and soccer players

Bone stress injuries (BSIs) frequently occur in the leg and foot long bones of female distance runners. A potential means of preventing BSIs is to participate in multidirectional sports when younger to build a more robust skeleton. The current cross-sectional study compared differences in tibia, fibula, and second metatarsal diaphysis size, shape, and strength between female collegiate-level athletes specialized in cross-country running (RUN, n = 16) and soccer (SOC, n = 16). Assessments were performed using high-resolution peripheral quantitative computed tomography and outcomes corrected for measures at the radius diaphysis to control for selection bias and systemic differences between groups. The tibia in SOC had a 7.5 % larger total area than RUN, with a 29.4 % greater minimum second moment of area (IMIN) and 8.2 % greater estimated failure load (all p ≤ 0.02). Tibial values in SOC exceeded reference data indicating positive adaptation. In contrast, values in RUN were similar to reference data suggesting running induced limited tibial adaptation. RUN did have a larger ratio between their maximum second moment of area (IMAX) and IMIN than both SOC and reference values. This suggests the unidirectional loading associated with running altered tibial shape with material distributed more in the anteroposterior (IMAX) direction as opposed to the mediolateral (IMIN) direction. Comparatively, SOC had a similar IMAX/IMIN ratio to reference data suggesting the larger tibia in SOC resulted from multiplane adaptation. In addition to enhanced size and strength of their tibia, SOC had enhanced structure and strength of their fibula and second metatarsal. At both sites, polar moment of inertia was approximately 25 % larger in SOC compared to RUN (all p = 0.03). These data support calls for young female athletes to delay specialization in running and participate in multidirectional sports, like soccer, to build a more robust skeleton that is potentially more protected against BSIs.

Study on interior beam–column joint sub-assemblage under bi-directional loading using finite element analysis

Purpose The purpose of this paper is to study the shearing performance under bi-directional loading of an interior beam–column joint (BCJ) sub-assemblage using the finite element analysis (FEA) tool (midas fea), validated in this research. Design/methodology/approach The BCJ can be defined as an essential part of the column that transfers the forces at the ends of the members connected to it. The members of the rigid jointed plane frame resist external forces by developing twisting moment, bending moment, axial force and shear force in the frame members. On the type of joints, the response to the action of lateral loads depends on reinforced concrete (RC) framed structures. The joint is considered rigid if the angle between the members remains unchanged during the structural deformation. This work examined the shear deformation, load displacement and strength of a non-seismically detailed internal concentric RC joint using non-linear FEA. The bi-directional loading imposes the oblique compression zone on one joint corner. This joint core’s oblique compression strut mechanism differs significantly from that under unidirectional loading. The numerical results are compared with experimental results in this study, with the data published in the literature. Findings Numerical analysis results show that, in the comparative study of numerical and experimental values, the FEA tool predicts the behaviour of the RC BCJ well. The discrepancy between the experimental and numerical results amounts to 6 to 12% end displacement of the beam, 7% resultant joint shear force, 4.23% column bar strain and 0.70% hoop strain. Originality/value The current code of practice describes the joint sub-assemblage behaviour along the single axis individually. In the non-orthogonal system, the superposition of the two axes for joint space results in overlapping the stresses and, hence, the formation of the oblique strut. This may result in a reduction in the joint capacity under bi-directional loading. The behaviour must be explored in depth, and an attempt is made for further exploration.

Spatial rotational behaviour of intact and damaged column foot joints: numerical modelling

Columns in traditional Chinese timber structures barely rest on stone bases, and the column foot joints are capable of resisting moment around any direction. This study numerically investigated the spatial rotational behaviour of intact and damaged columns based on experiments. Unidirectional cyclic loading tests were carried out on two intact and three damaged column foot joint specimens. A fibre element-based numerical model for the column foot joints was developed and validated by use of the unidirectional loading test results. Numerical analyses were performed based on the fibre element-based model to obtain the rotational behaviour of the intact and damaged column foot joints under spatial loading. The analyses indicated that the moment–rotation curve of an intact column foot joint under spatial loading was on an umbrella-shaped surface. The damage at the column foot not only unidirectionally decreased the moment-resisting capacity of a column foot joint but also resulted in a rotational performance degradation valley on the moment–rotation surface of the joint. The rotational behaviour of both the intact and damaged column foot joints under spatial loading was highly non-linear. This developed fibre element-based model can be further utilised to analyse the structural performance of traditional timber structures under three-dimensional excitations.

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

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

Evaluating the Mechanical Strength of Three Dimensionally (3D) Printed Implants in Septorhinoplasty through Finite Element Analysis (FEA).

Autologous nasoseptal cartilage grafts are used to correct nasal asymmetry and deviation in rhinoplasty, but patients who have undergone multiple surgeries may have limited autologous cartilage tissue available. 3D-printed L-strut implants may address these challenges in the future, but their mechanical strength is understudied. Silk fibroin-gelatin (SFG), polycaprolactone (PCL), and polylactide (PLA) are bio-inks known for their strength. We present Finite Element Analysis (FEA) models comparing the mechanical strength of 3D-printed SFG, PCL, and PLA implants with nasoseptal cartilage grafts when autologous or allografts are not available. FEA models compared the stress and deformation responses of 3D-printed solid and scaffold implant replacements to cartilage. To simulate a daily force from overlying soft tissue, a unidirectional load was applied at the "keystone" region given its structural role and compared with native cartilaginous properties. 3D-printed solid SFG, PCL, and PLA and scaffold PCL and PLA models demonstrated lower deformations compared to cartilage. Solid SFG balanced strength and flexibility. The maximum stress was below all materials' yield stresses suggesting their deformations are unlikely permanent under a daily load. Our FEA models suggest that 3D-printed L-strut implants carry promising mechanical strength. Solid SFG's results mimicked cartilage's mechanical behavior. Thus, scaffold SFG merits further geometric optimization for potential use for cartilage substitution. 3D-printed septal cartilage replacement implants can potentially enhance surgical management of patients who lack available donor cartilage in select settings. Computational simulations can evaluate 3D-printed implant strength and their potential to replace septal cartilage in septorhinoplasty.

Strain-rate effect on mechanical properties of rock-like specimens with narrow crack under uniaxial compression

Uniaxial compression tests were carried out on rock-like specimens containing prefabricated narrow crack under various strain rates. Experimental observations and numerical results show that narrow crack will close or partially close or expand under low compressive stress. Due to the unidirectional loading of loading device, the deformation degree of crack tip near the loading end was different with that of crack tip near the bearing end. With the increase of strain rate, the cracking modes can be divided into 3 categories, near vertical splitting failure affected by horizontal crack (α = 0°), anti-N-wing crack (15°≤α ≤ 60°) and wing crack (60°<α ≤ 90°). Both of the initiation angle θ1 of crack tip near the loading end and θ2 of crack tip near the bearing end decreased with the increase of α and strain rate. Specially, when α = 90°, both θ1 and θ2 rose with the increase of strain rate. Moreover, the value of θ2 was greater than that of θ1 under the same α value because of the different deformation characteristics at two tips. Besides, the mechanical properties of fissured rock including peak compressive stress, residual compressive stress, strain at peak stress, elastic modulus and post-peak softening modulus were significantly influenced by the strain rate and inclination angles.

Interaction of a non-axisymmetric artificial single spatula with rough surfaces.

Hair-like attachment structures are frequently used by animals to create stable contact with rough surfaces. Previous studies focused primarily on axisymmetric biomimetic models of artificial spatulas, such as those with a mushroom-shaped and cylinder-shaped geometry, in order to simulate the so-called gecko effect. Here, two geometric prototypes of artificial adhesive structures with non-axisymmetric properties were designed. The investigation of the prototype's interactions with rough surfaces was carried out using the finite element software ABAQUS. Under increasing vertical displacement, the effect of asperity size on the contact pressure evolution of the spatula was investigated. It has been demonstrated that the contact behaviour is greatly affected by the flexibility of the spatula, which is caused by its variable thickness. The thinner spatula shows a higher nominal contact area and attaches more strongly to various rough surfaces. Although a thicker spatula is more susceptible to the 'leverage' phenomenon, which occurs when excessively applied displacements prematurely reduce the nominal contact area, it obtains the ability to regulate attachment during unidirectional loading. Two non-axisymmetric prototypes provide different design concepts for the artificial adhesives. It is hoped that this study will provide fresh viewpoints and innovations that contribute to the development of biologically inspired adhesives.

Experimental Study on Shear Lag Effect of Long-Span Wide Prestressed Concrete Cable-Stayed Bridge Box Girder under Eccentric Load

Based on the engineering background of the wide-width single cable-stayed bridge, the shear lag effects of the cross-section of these bridge box girders under the action of the eccentric load were experimentally studied. The behavior of shear lag effects in the horizontal and longitudinal bridge directions under eccentric load in the operational stage of a single cable-stayed bridge was analyzed by a model testing method and a finite element (FE) analytical method. The results showed that the plane stress calculation under unidirectional live load was similar to the results from spatial FE analysis and structural calculations performed according to the effective flange width described in the design specification. At the position of the main beam near the cable force point of action, the positive stress at its upper wing edge was greatest. At a distance from the cable tension point, the maximum positive stress position trend showed that from the center of the top flange to the junction of the top flange and the middle web to the junction of the top flange and the middle web and the side web. Under eccentric load, the positive and negative shear lag effects on the end fulcrum existed at the same time, and the shear lag coefficient on the web plate was larger than the shear lag coefficient on the unforced side. Due to the influence of constraint at the middle fulcrum near the middle pivot point, positive and negative shear lag effects were significant, and the coefficient variation range was large, resulting in large tensile stress on the roof plate in this area. According to FE analytical results, stress and shear forces of a single box three-chamber box girder under eccentric load were theoretically analyzed, the bending load decomposed into the accumulation of bending moment and axial force, using the bar simulation method, and the overall shear lag effect coefficient λ was obtained and verified.

Experimental investigation on flexural performance of concrete beams strengthened with SMA-GFRP-ECC smart composite materials

The structural performance improvement of concrete members is by far a crucial theoretical issue for engineers, and the development of modern smart and composite materials makes it possible to gradually enhance the durability design of the concrete structure. In this study, six beams of the same size and reinforcement ratio, the proposed composite beam (SMA-GFRP-ECC) and five comparative beams (RC, R-ECC, SS-ECC, GFRP-ECC, SMA-ECC), were designed and tested under low-cycle unidirectional cyclic loading and unloading conditions. The energy dissipation capacity, displacement ductility, residual deformation, and self-repairing performance of each concrete beam were evaluated. Afterward, a concise calculation model for the studied composite beam is deduced and developed based on the existing relevant constitutive models and concrete assumptions. The test results indicate that compared with RC beams, the composite reinforced ECC beams show obvious multi-cracking and smaller crack width during the loading process and have good bending ductility. The innovative SMA-GFRP-ECC beam is capable of a high bearing capacity, ductility, and damage self-repairing. The new proposed beam has more than 80% of the maximum crack width recovery capacity during unloading. Hence, the proposed SMA-GFRP-ECC beam is a rather good first attempt of strengthened beams, combining the advantages of SMA, GFRP, and ECC.

Disturbance range characterization and reinforcement design method of concealed bedding slope

The concealed bedding slopes exhibit sudden and extensive failure characteristics, harboring significant safety hazards. It is crucial to employ rapid and accurate methods to determine excavation disturbance ranges and reinforcement forces to prevent such slope disasters. This paper first analyzes the failure characteristics of slope excavation to reveal the mechanism of slope failure. Secondly, a novel method was proposed to calculate excavation disturbance ranges and solve for active reinforcement forces. Thirdly, the rationality of the method was validated through numerical simulation experiments. Finally, the method was applied to engineering. The results are as follows:(1) Excavation induces plastic shear failure of structural planes first, and the strength of the structural plane will be reduced, resulting in extrusion shear deformation of the rock mass at the foot of the slope under greater unidirectional load along the structural plane, forming a shear sliding surface. (2) From both strength and deformation perspectives, a method for calculating disturbance ranges in excavated slopes is proposed. This method determines key indicators for analyzing two disturbance range factors: ultimate height and disturbance thickness. The disturbance range is divided into shear plastic zones and traction sliding zones. (3) An active reinforcement design method is proposed considering the timing, scope, and force of reinforcement. The disturbance thickness is used to determine the reinforcement range, while the ultimate height is used to determine the timing of reinforcement. Active reinforcement forces are calculated based on the equilibrium of forces and deformation amounts. (4) A comparison with the Finite Element Method (FEM) shows that during excavation, the disturbance ranges and reinforcement forces calculated using this method are slightly larger than those obtained from the FEM. The calculations are fast, and as the excavation height approaches the limit slope height, the disturbance thickness and horizontal deformations closely match the FEM results, ensuring safety. It can provide monitoring, early warning and reinforcement guidance for bedding slope construction.

Evaluating the effect of unidirectional loading on the piezoresistive characteristics of carbon nanoparticles

The piezoresistive effect of materials can be adopted for a plethora of sensing applications, including force sensors, structural health monitoring, motion detection in fabrics and wearable, etc. Although metals are the most widely adopted material for sensors due to their reliability and affordability, they are significantly affected by temperature. This work examines the piezoresistive performance of carbon nanoparticle (CNP) bulk powders and discusses their potential applications based on strain-induced changes in their resistance and displacement. The experimental results are correlated with the characteristics of the nanoparticles, namely, dimensionality and structure. This report comprehensively characterizes the piezoresistive behavior of carbon black (CB), onion-like carbon (OLC), carbon nanohorns (CNH), carbon nanotubes (CNT), dispersed carbon nanotubes (CNT-D), graphite flakes (GF), and graphene nanoplatelets (GNP). The characterization includes assessment of the ohmic range, load-dependent electrical resistance and displacement tracking, a modified gauge factor for bulk powders, and morphological evaluation of the CNP. Two-dimensional nanostructures exhibit promising results for low loads due to their constant compression-to-displacement relationship. Additionally, GF could also be used for high load applications. OLC’s compression-to-displacement relationship fluctuates, however, for high load it tends to stabilize. CNH could be applicable for both low and high loading conditions since its compression-to-displacement relationship fluctuates in the mid-load range. CB and CNT show the most promising results, as demonstrated by their linear load-resistance curves (logarithmic scale) and constant compression-to-displacement relationship. The dispersion process for CNT is unnecessary, as smaller agglomerates cause fluctuations in their compression-to-displacement relationship with negligible influence on its electrical performance.

Establishment of a Uniaxial Tensile Fracture Inversion Model Based on Fracture Surface Reconstruction (FRASTA)

In order to infer the load on the component after the experimental uniaxial tensile fracture inversion model based on cross-sectional reconstruction, (FRASTA) was proposed to infer the load on the tested components. This model can combine the fracture surface characteristics of experimental specimens to reconstruct the fracture surface morphology and invert the fracture process of uniaxial tensile specimens. Based on the assumption of rectangular rod fracture, a quantitative inversion model for a unidirectional stress load based on dissipative plasticity characteristics was established, and the inversion results based on cross-sectional reconstruction were compared with the experimental measurement results. The results indicate that when only considering the unidirectional stress state, the two have a high degree of consistency, with a maximum measurement error of 5.3%, fully verifying the accuracy of the fracture surface reconstruction and inversion model.