Deformation Of Specimens Research Articles

Longitudinal wave propagation determination in concrete specimen under impact loading by ultrahigh-speed camera image sequence and strain gauge data analysis

Abstract To demonstrate the potential of an ultrahigh-speed camera with frame rates beyond a million images per second for high dynamic material analysis, cylindrical concrete specimens are tested under compression at strain rates up to 164.3 s-1 in a split Hopkinson pressure bar facility. The evaluation includes the determination of the actual longitudinal wave propagation velocity and the induced longitudinal deformations. The results obtained from image sequence analysis are validated with those obtained by the well-established strain gauge measuring technique that estimate the specimen deformation in the same facility. Data analysis for both measuring techniques is based on the one-dimensional wave theory. Image quality challenges affecting the material analysis are overcome by applying a Bézier fitting filter to the image sequences. Using the image-sequence-based approach to select stress-wave-induced motion points, different wave characteristics are acquired. Subsequently, selecting the points in compression during the first stress wave transit yields longitudinal wave propagation velocities up to 2995 m/s with a standard deviation of 265 m/s. From the validation results, first, an observed bilateral complementarity of both techniques enables a comprehensive analysis of the specimen deformation. Second, individual discrepancies between the material properties obtained from both techniques up to ultimate compressive strength for deformation, velocity, strain, and stress of 20.8 %, 14.4 %, 8.3 %, and 10.0 %, respectively, are achieved.

Oxyacetylene Flame Forming of Thick Steel Plates

One of the most widely used processes in ship hull plate manufacturing is the flame forming process (FFP). In this work, the fabrication of saddle-shaped specimens with FFP using a spiral irradiating pattern is studied experimentally. The deformation of the deformed plates by FFP based on the spiral irradiating pattern is affected by process parameters such as the pitch of spiral passes (PSP), the radius of the starting circle (RSC), and the number of irradiation passes (NIP). However, in this work, the effects of process parameters on the deformation of SSS are statistically examined by the design of experiment (DOE) method based on response surface methodology (RSM). The experimental and statistical results show that the deformation of flame-formed SSS increases with the increase in RSC and NIP and the decrease in PSP. In addition, the results of the optimization procedure demonstrate that the maximum value of deformations of flame-formed saddle-shaped specimens is achieved by adjusting the process parameters as follows: PSP = 10 mm, RSC = 75 mm, and five NIPs.

Experimental Study on the Freeze–Thaw Characteristics of Clays with Different Initial Moisture Contents and Thawing Temperatures

Abstract To reveal the effects of the thawing temperature and initial moisture content on the freeze–thaw (F-T) characteristics of clays, F-T tests were performed on clays with three initial moisture contents (25 %, 30 %, and 35 %) at two thawing temperatures (25°C and 70°C). Changes in water content of specimens before and after F-T and the phenomena changes at the top surface of specimens after F-T were analyzed. The relationship between the change of water content and the pot-cover effect and surface cracking were discussed. The results showed that stable temperatures at the freezing of the specimens with initial moisture contents of 30 % and 35 % were 14.7 % and 79 %, respectively, both lower than that of the specimen with initial moisture contents of 25 %. With a thawing temperature of 70°C, the time to reach 0°C of the specimen was reduced by 35.9 % to 40.57 %, and the thaw settlement coefficient was reduced by 2.4 % to 4.75 %. When the temperature changes, the deformation of specimens also change and present certain hysteresis during F-T. The upwards net change occurred after F-T; at that time, the total water content inside the specimen decreased, the water content in the upper part of the specimen decreased, and the water content in the lower part of the specimen increased. At the same time, the pot-cover effect occurred on the top surface of the specimen, and the cracking appeared on the top surface and inside the specimen. More moisture migrated upwards to the top of the specimens and the mass of water in the specimen after F-T was less with a thawing temperature of 70°C. Based on the test results, some suggestions are provided for construction of cross passages with AGF and the forced thawing method.

Real-time monitoring of asphalt pavement structure fatigue response based on tri-axis accelerometer

ABSTRACT Fatigue damage is a notable distress of asphalt pavements. However, monitoring the development process of such distresses in real-time remained challenges for researchers. In this paper, the self-developed sensing facility has been utilized to obtain aggregate kinematic response of semi-circular specimen during the fatigue loading process in the upper-middle (H/2), lower-middle (L/2) and lower-right (L/3) positions of the specimen. Angle and acceleration variation in the X, Y, and Z directions were analysed independently at three positions. The correlation between the kinematic characteristic of the aggregate and the vertical deformation of the asphalt mixture specimen is established. The results illustrated that the asphalt mixture viscoelasticity attenuation during fatigue test caused the angle accumulation and acceleration response change of the specimen. The angle accumulation in the X-axis direction and acceleration variation in Y-axis direction of the aggregate at the H/2 position exhibited a significant three-stage change. Angle-Accumulation Rate (AAR) of change is suggested as a long-term monitoring index for the fatigue development of the asphalt mixture. The proposal of AAR index creatively combines the long-term kinematic behaviour and mechanical behaviour of asphalt mixture, making long-term and real-time monitoring of the asphalt pavement health from the perspective of kinematics become possible.

The Effect of Elastomer Content and Annealing on the Physical Properties of Upcycled Polyethylene Terephthalate-Maleated Styrene Ethylene Butylene Styrene Blends for Additive Manufacturing.

In the work presented here, we explore the upcycling of polyethylene terephthalate (PET) that was derived from water bottles. The material was granulated and extruded into a filament compatible with fused filament fabrication (FFF) additive manufacturing platforms. Three iterations of PET combined with a thermoplastic elastomer, styrene ethylene butylene styrene with a maleic anhydride graft (SEBS-g-MA), were made with 5, 10, and 20% by mass elastomer content. The elastomer and specific mass percentages were chosen based on prior successes involving acrylonitrile butadiene styrene (ABS), in which the maleic anhydride graft enabled compatibility between different materials. The rheological properties of PET and the PET/SEBS blends were characterized by the melt flow index and dynamic mechanical analysis. The addition of SEBS-g-MA did not have a significant impact on mechanical properties, as determined by tensile and impact testing, where all test specimens were manufactured by FFF. Delamination of the tensile specimens convoluted the ability to discern differences in the mechanical properties, particularly % elongation. Annealing of the specimens enabled the observation of the effect of elastomer content on the mechanical properties, particularly in the case of impact testing, where the impact strength increased with the increase in SEBS content. However, annealing led to shrinkage of the specimens, detracting from the realized benefits of the thermal process. Scanning electron microscopy of spent tensile specimens revealed that, in the non-annealed condition, SEBS formed nodules that would detach from the PET matrix during the tensile test, indicating that a robust bond was not present. The addition of SEBS-g-MA did allow for shape memory property characterization, where deformation of tensile specimens occurred at room temperature. Specimens from the 20% by mass elastomer content sample group exhibited a shape fixation ratio on the order of 99% and a shape recovery ratio on the order of 80%. This work demonstrates a potential waste reduction strategy to tackle the problem of polymer waste by upcycling discarded plastic into a feedstock material for additive manufacturing with shape memory properties.

Long-Term Settlement Prediction for Over- Consolidated Soft Clay under Low Embankment

The long-term post-construction settlement of an embankment laid on a deep, soft soil foundation can give rise to a series of safety concerns and significant structural damage. The settlement is primarily attributed to the creep deformation of the soft soil following the removal of the surcharge load and the impact of traffic loads on the soft soil. In this study, a plan strain triaxial test was conducted to investigate the deformation of an undisturbed soft clay specimen subjected to static and cyclic loading. The results demonstrate that the volume creep and vertical creep are associated with the overconsolidation state of the soft soil. The Over-Consolidated Ratio (OCRq) of shear stress, can be used as a parameter to describe the state of overconsolidation of soft soil under spherical stress. Based on the vertical creep coefficient and considering the influence of stress history on the stress state of soft soil, a two-dimensional long-term settlement model under cyclic loading has been proposed.

The Effect of Specimen Width on the Deformation Behavior and Formability of cp-Ti Grade 4 Sheets During Uniaxial and Cyclic Bending Under Tension Loading.

This study examines the specimen size-dependent deformation behavior of commercially pure titanium grade 4 (cp-Ti grade 4) sheets under tension, with strain paths between uniaxial tension (UT) and plane-strain tension and compares the results with cyclic bending under tension (CBT) data. Specimens of varying widths (11.7, 20, 60, 100, and 140 mm) were tested in both rolling (RD) and transverse (TD) directions. The research employed digital image correlation for full-field strain measurements, finite element simulations, and fracture surface thickness data. Contrary to traditional forming concepts, i.e., the forming limit diagram (FLD) has the lowest major strain at the plane-strain condition, and the fracture forming limit has decreased major strain with increasing (less negative) minor strain, wider specimens exhibited higher major strains at strain localization and fracture under UT. In contrast, CBT findings showed decreased formability with increasing width, i.e., closer to plane-strain deformation, as expected. Strain distribution analyses revealed a transition from nearly uniform deformation in narrow specimens to multiaxial strain states in wider specimens. Thickness measurements along the fracture surface revealed a steeper profile in UT compared to CBT, indicating more localized deformation and necking in UT. In comparison with AA6016-T4, the cp-Ti grade 4 showed greater thickness, suggesting lower susceptibility to localized thinning. Strong anisotropy was observed between the RD and TD, with TD specimens showing higher formability and steeper thickness gradients in UT. Strain fields, along with thickness reduction and adiabatic heating, are used to rationalize the observed width-sensitive deformation behavior of cp-Ti sheets. Notably, CBT improved overall formability compared to UT due to its ability to distribute strain more evenly and delay critical necking. The contrasting trends between simple UT and CBT emphasize the relationship between loading conditions, specimen geometry, and material behavior in determining formability. These findings highlight the ability of the CBT test to create known and desired deformation effects, i.e., lower major strain at failure with increasing specimen width, and more uniform deformation, i.e., consistent thinning across the specimen width, for cp-Ti. Given the observed effects of width in UT, the selection of the testing method is critical for cp-Ti to ensure that results reflect expected material behavior.

Layer thickness dependent strengthening and strain delocalization mechanism in CuTa nanopillars with nanoscale amorphous/amorphous interfaces

Introducing amorphous/amorphous interfaces in metallic glasses offers an effective strategy to address the strength-plasticity trade-off by suppressing the strain localization. Elucidating the underlying size-dependent deformation mechanisms is crucial for designing strong and ductile amorphous nanolayered materials. Herein, molecular dynamics simulations are conducted to investigate the deformation behaviors of Cu70Ta30/Cu30Ta70 amorphous/amorphous nanopillars (AANPs) under compression, focusing on the intrinsic size effect of amorphous layer thickness. The results indicate a critical layer thickness of approximately 6.7 nm, below which an inverse Hall-Petch relation occurs. This transition is attributed to a shift in dominant deformation mode from the necking and localized deformation to the relatively homogeneous deformation as the layer thicknesses decreases. These A/A interfaces could be considered as a third medium phase in nanolaminates, especially when the thickness is very low, down to only a few of nm. The mechanical properties and deformation behavior of transitional interface phase lie between those of soft and hard phases, balancing heterogeneous deformation between hard and soft layers and resulting in homogeneous flow deformation of specimen with thinner amorphous layer. These findings provide insight for designing ductile amorphous materials through architecting nanoscale amorphous/amorphous interfaces.

Experimental study of reinforced concrete rocking columns with steel tubes under cyclic loading

To reduce damage and enhance the seismic resilience of reinforced concrete (RC) columns, this study introduces a new type of RC rocking column installed with steel tubes for end protection and steel angles as external dampers to enhance the energy dissipation capacity. Six full-scale specimens including four RC rocking columns without steel angles and two with steel angles were tested under cyclic loading. The results demonstrate that the proposed end protection measure significantly mitigates the damage to RC rocking columns. The residual deformation of specimens was small after testing. As the axial compression ratio increases, the strength of RC rocking columns also increases. However, a higher axial force results in greater damage and increased residual deformation. Steel angles significantly enhance the strength, stiffness, and energy dissipation capacity of RC rocking columns. Additionally, the repair of the RC rocking column is straightforward, and the recovery of its function is rapid after strong earthquakes.

The influence of plastic flow localization on the surface morphology of aluminum alloy specimens subjected to complex loading

This study investigates the effects of complex (nonproportional) loading on plastic deformation in aluminum alloys (Al-6% Mg), with a focus on understanding surface morphology changes driven by the Portevin–Le Chatelier effect. Mechanical tests on the deformation of thin-walled tubular specimens were carried out on an Instron 8850 two-axis servohydraulic testing system. Quantitative analysis of the lateral surface of the specimens roughness was carried out based on data obtained using a NewView 5010 interferometer-profilometer. Localized plasticity zones in a wide spectrum of spatial scales were determined using the Hurst exponent as a roughness characteristic. The results of measuring changes in the surface geometry of specimens under various programs of complex (disproportionate) loading are presented. A compact representation of data on the specimens surface relief in the form of amplitude-frequency characteristics was obtained using wavelet analysis. The results obtained can be used to assess the surface roughness of products, especially at the final stages of their manufacturing process by plastic deformation.

Development of accelerated test methods by electromigration to assess the risk of internal sulfate attack in heat-cured mortar and concrete

Internal sulfate attack induces the formation of delayed ettringite (DEF) in hardened cement-based materials. DEF is a complex phenomenon, detrimental to the durability of concrete and which develops in the long term, depending on the temperature history of the material at early age, its composition, its physicochemical and mechanical properties, and the environmental conditions. Today, the risk assessment and prediction of this pathology are still mainly based on laboratory tests which can extend over several months, or even several years. In this context, the objective of the present study is to develop two original experimental devices, making it possible to shorten the time needed to detect the risk of potential internal sulphate attack, using the application of an electric field on mortar and concrete specimens. The results obtained, coupled with microstructural observations carried out using scanning electronic microscopy, show that the two devices make it possible to both accelerate DEF, through electromigration, and measure simultaneously, continuously and automatically the longitudinal and lateral specimen deformations related to the formation of delayed ettringite. Using the devices developed, the time needed to observe the swelling threshold of 0.04 % is divided by a ratio of 2–2.5 and 1.7–1.9 between the mortar and concrete specimens subjected to electric field and the control mortar and concrete specimens, respectively.

Mechanical Behaviour of 7075-T6 Aluminium Alloy: Integrating Digital Image Correlation and Finite Element Analysis for Uniaxial and Biaxial Load Scenarios

The objective of this study is to investigate the mechanical properties of 7075-T6 Aluminium (Al) alloy under both uniaxial and biaxial loads. The study will be conducted using a combination of experimental and numerical methods. The experimental method used is the digital image correlation (DIC) technique, which was utilized to capture the deformation and strain fields of the material specimen under tensile test. A tensile machine was employed to apply uniaxial and biaxial loads on the sample. The strain and deformation distribution of the results was generated on the DIC and correlated software. The numerical method involved the use of a commercial finite element software to create a finite element model and simulate the mechanical behaviour of the material under the same loading conditions. The results obtained from the experimental and numerical methods were compared to validate the accuracy of the numerical model. The outcomes demonstrated that under uniaxial loading, localized necking and fracture were observed, while biaxial loading resulted in shear deformation and fracture. This research contributes to the development of more accurate models for predicting the mechanical behaviour of the model samples under different loading conditions.

Evaluation and Prediction of Mechanical Properties According to Welding Methods of Ni 825/A516-70N Clad Plates

In this study, the microstructures and mechanical properties of different methods of FCAW (Flux-cored arc welding) + FCAW or FCAW + GTAW (Gas tungsten arc welding) welding on Ni825/A516-70N clad plate were investigated, using a double U groove angle on a laboratory scale. The amount of specimen deformation with FCAW + FCAW welding was ~1.5 mm, and that with FCAW + GTAW welding was ~3.6 mm. In the Vickers hardness tests, the average hardness value of the FCAW + GTAW welding specimens tended to be higher, and the hardness of the steel showed the same value. Also, in the tensile tests, the maximum strength and elongation of the FCAW + GTAW specimens were found to be higher. The SEM analysis of the welding boundaries of each specimen revealed the phenomenon of grain refinement in the specimens with FCAW + GTAW welding. This was due to the slow welding speed of this welding process and the rapid cooling rate caused by the relatively low layer thickness despite the relatively high number of weld passes. The computer simulation of the amounts of deformation were similar, with a value of 1.5 mm for FCAW + FCAW and 3.6 mm for the computer simulation, indicating the credibility of the simulation. In the computational simulation of butt welding, FCAW + GTAW showed high values for both residual stress and angular strain. The L-seam and C-seam of the demo vessel size were welded under the same conditions as the actual welding. The residual stress and angular deformation in the L-seam were 849 MPa and 2.3 mm for the FCAW + FCAW and 852 MPa and 2.9 mm for FCAW + GTAW. The residual stress and angular deformation in the C-seam were 920 MPa and 0.7 mm for FCAW + FCAW and 930 MPa and 0.9 mm for FCAW + GTAW, respectively.

A permeability model considering the dynamic effect of stress on gas adsorption under discontinuous compression.

With the continuous advance of coal mining, the normal stress in front of coal seams will continue to increase, resulting in changes of internal structure and permeability of coal seams. During the continuous advance of mining face, the increase of vertical stress somewhere in front of coal seams may not be a transient process, but a gradual change process. Therefore, this paper carried out the seepage test of gas-containing coal under discontinuous loading axial stress. The stress, deformation and permeability of coal specimens were measured and recorded during the test, and the influence of discontinuous loading axial stress on the deformation, internal structure and seepage properties of coal specimens were discussed. On this basis, considering the influence of stress on the gas adsorption state, Klinkenberg effect and other factors, combined with Shi-Durucan permeability model, a new permeability model considering the dynamic adsorption state of coal specimens was developed.

Interfacial microstructure and fracture mechanism of Cu/Al composite plate jointing process assisted by pulsed current-melted Al spheres: Finite element analysis and experimental studies

In this work, a novel method based on pulsed-current-assisted vacuum sintering processes was employed to fabricate the Cu/Al laminated metal composites (LMCs) with outstanding mechanical properties. The microstructural evolution, interfacial characteristics, phase composition, mechanical properties, and fracture behavior of Cu/Al composites prepared by the melted Al spheres induced with high-frequency pulsed current were investigated. Results show that robust interfacial bonding without micropores and cracks, and the grain structure consists mainly of recrystallized and substructured grains characterized by high angular grain boundaries. Meanwhile, interfacial analysis identifies melted Al and Al2Cu phases within the transition layer, exhibiting distinctive features such as "Al+Al2Cu" corrugated interfaces and island eutectic structures. Additionally, mechanical properties demonstrate superior strength (210 ± 13 MPa) and elongation (27 % ± 0.7 %) in specimens with corrugated interfaces compared to those with flat interfaces. Finite element analysis further elucidates stress redistribution and fracture behavior, emphasizing the enhanced coordinated deformation in specimens featuring corrugated interfaces. These findings underscore the significance of interface engineering and microstructural refinement in optimizing the mechanical performance of Cu/Al composite materials, offering valuable insights for their application in diverse engineering domains.

Dynamic responses of thin-walled FRP-concrete-steel tubular wind turbine tower under horizontal impact loading: Experimental study and FE modelling

Thin-walled FRP-concrete-steel tubular towers (TW-FCSTs), composed of an outer FRP tube, an inner hollow steel tube, and an interlayer of concrete, represent a novel type of wind turbine tower with promising application prospects. Given their potential risks to potential vehicle or vessel collisions, this study investigates the dynamic responses of five cantilevered TW-FCSTs using a horizontal impact device. These TW-FCSTs possess significantly large void ratios (i.e., φ=0.73or0.82) and practical large column sizes (i.e., Dc = 300 mm, Hc = 1500 mm). The experimental programme of this paper investigates several key parameters, including FRP thickness, steel thickness, and void ratio of TW-FCSTs, as well as the velocity and numbers of impact loading. Experimental findings demonstrate the following insights: (1) cantilevered TW-FCSTs exhibit an overall flexural failure mode after the horizontal impact loading; (2) the increase in steel thickness or FRP thickness contributes to greater energy dissipation and reduced localized dent deformation; (3) the higher void ratio results in more pronounced localized dent deformation and less overall deformation in specimens; (4) the proportion of energy dissipation caused by localized dent deformation increased with impact velocity, signifying more severe localized dent deformation at higher impact velocities. The utilization of FE models in LS-DYNA effectively simulates the dynamic performance of cantilevered TW-FCSTs, offering reliable predictions. Parametric studies were conducted to analyze influences of impact mass, impact height, concrete strength, and steel yield strength.

The effect of the method for producing chromium-nickel stainless steel powders on the strain state and properties of the outer cage of a spherical hinge joint

The paper substantiates the relevance of studying powder metallurgy methods and efficiency of applying them to the production of spherical bearings of highly loaded spherical hinge joints. It proves that the force and work of deformation, as well as the kinetics of forming of the outer cage of a spherical hinge joint made of sintered corrosion-resistant chromium-nickel steels, are influenced by the chemical composition of powders and lubricants, the protective environment and the method of sintering, the microstructure and mechanical properties of the workpiece material. It is shown that the plastic properties of ring specimens under testing depend on the perfection of interparticle contacts, the presence and distribution of chromium oxides, forming schemes and workpiece porosity. The influence of the method for the production of stainless chromium-nickel powders on the density and mechanical properties of the sintered blanks is studied. A method is proposed for evaluating the strain state during radial deformation of ring specimens made of these steel powders and estimating the maximum allowable values of strain intensity below which no cracks are formed during cold forming of porous blanks. It is revealed that, to calculate the stress state and, accordingly, strain resistance in the cold forming of the outer cages of spherical hinge joints, made of sintered corrosion-resistant steels, it is possible to use the known constitutive equations if strain intensity does not exceed the experimentally obtained limit values. The feasibility of implementing the proposed method and selecting the process parameters of cold forming of spherical hinge parts made of chromium-nickel austenitic steels is substantiated.

Tension stiffening and cracking behaviors in glass fiber reinforced polymer bar enhanced precast recycled aggregate concrete specimen

Glass fiber reinforced polymer (GFRP) bar-enhanced precast recycled aggregate concrete (PRAC) elements combine PRAC’s environmental benefits with GFRP’s corrosion resistance, making them ideal for coastal urban infrastructure. However, in-depth research on the tensile stiffness and cracking behaviors of this composite is lacking. The significant mechanical differences between GFRP bars (low modulus, high strength) and PRAC, as compared to traditional materials, raise safety concerns for widespread use. This study investigates the short-term load capacity, deformation and cracking characteristics of GFRP bar-reinforced PRAC tensile specimens through tests and analyses. The tests examine how variables like water-to-binder ratio, coarse aggregate type, recycled aggregate (RA) content and mixing methods affect the specimens' mechanical responses. Theoretical analyses, using existing equations and a partial interaction model, clarify stress-strain relationships and crack propagation under applied loads, revealing: (a) As RA content increases, PRAC shows a moderate decrease in workability and mechanical performance. The strength variability in PRAC generally falls between that of natural aggregate concrete (NAC) and conventional recycled aggregate concrete (CRAC) using RAs from construction and demolition waste, being closer to NAC. Additionally, the strength conversion relation seen in NAC applies similarly to PRAC. (b) During tension at both ends of the specimen, PRAC's resistance decreases by 24.3 % compared to NAC but is still 20.3 % higher than CRAC. (c) The number of cracks in the PRAC specimen decreases with higher RA content and basalt fibers, while the ratio of stabilized load to cracking load increases. (d) The CEB-FIP standard offers more accurate predictions of the specimen’s composite stress-strain relation, while the Chinese code excels in predicting crack width. The partial interaction model effectively predicts the specimen’s load, deformation and crack characteristics by accounting for the behaviors and bonding of both PRAC and GFRP bars.

Numerical investigation of welding deformation diminution for double shell structure using the layered inherent strain

Cyclotron is a key scientific tool and indispensable research platform for conducting cutting-edge research in nuclear equipment development as well as innovative applications of nuclear technology. The shell component has a double-layer thick-walled structure with intricate ribs and high-density, full-penetration welded joints. The mitigation of welding deformation is of profound significance to the performance of the cyclotron. The thick plate joint has many welding layers which will be divided into several steps to complete the backing, filler, and cap welding. The equivalent transverse and longitudinal plastic strains of different layers were extracted by the thermo-elastic-plastic method. The welding deformation generated by each layer of weld can be predicted by using the equivalent plastic strain, and the total distortion can be accumulated layer by layer. Numerical simulation and experimental studies were conducted on the welding deformation of the double shell specimen, and the welding sequence and design of the welding fixture were discussed in detail. The digital photogrammetry system was used to monitor the deformation state of the welded parts in real-time. The measured deformation was compared with the simulation results. Ultimately, the deformation of the specimen is controlled at 2.64 mm. The proposed method can flexibly evaluate the impact of each welding layer on welding deformation for multiple welds, which can provide technical guidance for cyclotron engineering manufacturing.

PROPIEDADES DINÁMICAS DE IMPACTO DE COMPUESTOS DE LODOS DE PAPEL DOPADOS CON OXICLORURO DE MAGNESIO

To address the heavy pollution caused by paper sludge, this study investigates a novel approach by incorporating paper sludge into magnesium oxychloride cement to develop a new type of concrete composite material. To achieve waste utilisation, cost savings and pollution reduction, the impact dynamics properties of the concrete specimens were conducted using an electromagnetically driven Hopkinson pressure bar, while a high-speed camera recorded the specimen destruction process, stress-strain curve, destruction morphology, deformation field, and evolution of energy consumption. Results show that as the paper sludge doping increases, the peak stress of the stress-strain curve and the energy consumption gradually increase. Increasing the voltage leads to a gradual rise in peak stress and energy consumption of the specimen. During the impact test, the transverse fissures gradually are developed in the test block, and as the impact stress increases, the fissures are widened until the specimen eventually being fractured. Moreover, the higher impact voltage and paper sludge content result in the increased specimen displacement and strain. It is expected that nearly 50% of paper sludge will be recycled every year by this method, which will save 10%-20% of raw materials. The conclusions obtained in this study provide a reference for the engineering application of the paper sludge concrete composites. Keywords: Paper sludge, Magnesium oxychloride, Digital image correlation, Energy consumption, Impact dynamic properties.