Cylindrical Compression Test Research Articles

Study on the mechanical property and durability of alkali-activated seawater and sea sand recycled aggregate concrete

This study investigates the potential of Alkali-Activated Seawater Sea Sand Recycled Aggregate Concrete (ASSRAC) as a novel sustainable construction material. By utilizing recycled aggregates from construction and demolition waste, seawater, sea sand, and alkali-activated materials such as fly ash and blast furnace slag, this innovative concrete aims to mitigate carbon emissions from cement production and optimize resource usage. The impact of recycled aggregate replacement rate, water-to-binder ratio, and sand type on the compressive strength of ASSRAC was examined through analysis of variance. Cylindrical axial compression and prism flexural tests were conducted to evaluate the long-term performance of ASSRAC under seawater immersion. The results indicate a decrease in compressive strength with higher recycled aggregate replacement rates and water-to-binder ratios, with recycled aggregates being the primary weak link. Additionally, increasing the water-to-binder ratio hampers hydration by diluting alkali activators, weakening polycondensation reactions. Under seawater immersion, ongoing reactions foster denser C-(A)-S-H structures, enhancing compressive strength and elastic modulus over time. Moreover, higher recycled aggregate replacement rates result in improved ductility, attributed to reactions between the old mortar on recycled aggregate surfaces and slag/fly ash at interfaces. For specimens immersed for 0 and 90 days, most theoretical models accurately predict results, except for the CEB-FIP model, which only accurately reflects the stress-strain curve at 180 days. The seawater-sea sand group's flexural strength initially exceeds that of the freshwater-river sand group due to accelerated early hydration, but this advantage diminishes over time due to high salt content.

An Optimized Strain-Compensated Arrhenius Constitutive Model of GH4169 Superalloy Based on Hot Compression.

A precise constitutive model is essential for capturing the deformation characteristics of the GH4169 superalloy in numerical simulations of thermal plastic forming processes. Hence, the aim of this study was to develop a precise modified constitutive model to describe the hot deformation behavior exhibited by the GH4169 superalloy. The isothermal cylindrical uniaxial compression tests of the GH4169 superalloy were carried out at temperatures of 950~1100 °C and strain rates of 0.01~10 s-1 using a Thermecmastor-200KN thermal-mechanical simulator. The original strain-stress curves were corrected by minimizing the effects of plastic heat and interfacial friction. Based on the true stress-strain curves, the original strain-compensated Arrhenius constitutive model was constructed using polynomial orders of 3, 5, and 10, respectively. The results showed that once the polynomial order exceeds the 5th, further increasing the order has little contribution to the accuracy of the model. To improve prediction ability, a higher precision Arrhenius constitutive model was established by extending a series of material parameters as functions that depend on temperature, strain, and strain rate, in which the error can be reduced from 4.767% to 0.901% compared with the classic strain-compensated Arrhenius constitutive model.

Prediction of Grain Size in a High Cobalt Nickel-Based Superalloy.

With the advancement in computational approaches and experimental, simulation, and modeling tools in recent decades, a trial-and-validation method is attracting more attention in the materials community. The development of powder metallurgy Ni-based superalloys is a vivid example that relies on simulation and experiments to produce desired microstructure and properties in a tightly controlled manner. In this research, we show an integrated approach to predicting the grain size of industrial forgings starting from lab-scale cylindrical compression by employing modeling and experimental validation. (a) Cylindrical compression tests to obtain accurate flow stress data and the hot working processing window; (b) double-cone tests of laboratory scale validation; (c) sub-scale forgings for further validation under production conditions; and (d) application and validation on full-scale industrial forgings. The procedure uses modeling and simulation to predict metal flow, strain, strain rate, temperature, and the resulting grain size as a function of thermo-mechanical processing conditions. The models are calibrated with experimental data until the accuracy of the modeling predictions is at an acceptable level, which is defined as the accuracy at which the results can be used to design and evaluate industrial forgings.

Study of Interfacial Adhesion and Re-Ir Alloy Coating in Chalcogenide Glass Molding.

Precision glass molding (PGM) has become an efficacious technique to fabricate high-precision optics. Chalcogenide (ChG) glass is increasingly used in thermal imaging, night vision, etc., because of its excellent infrared optical properties. Nevertheless, glass-mold interfacial adhesion has emerged as a pivotal issue within the PGM process. The interfacial adhesion during PGM has the potential to significantly undermine the performance of molded optics and reduce the longevity of molds. It is important to investigate interfacial adhesion behaviors in the PGM. In this study, the interfacial adhesion mechanism between ChG glass and the nickel-phosphorus (Ni-P) mold is analyzed using the cylindrical compression test. The effect of ChG glass internal stress on physical adhesion is investigated by finite element method (FEM) simulation. The spherical preform is proven to be capable of reducing the stress concentration and preventing physical adhesion. More importantly, a rhenium-iridium (Re-Ir) alloy coating is deposited on the Ni-P mold surface by ion sputtering to prevent atomic diffusion and resolve the problem of chemical adhesion. Finally, ChG glass microstructures with high accuracy are fabricated using the spherical ChG glass preform and the Re-Ir-coated Ni-P mold by PGM.

Ultrahigh strength-ductility of nanocrystalline Cr2AlC coating under micropillar compression

MAX phases gain increasing attention as protective coatings due to superior anti-corrosion and oxidation resistance for harsh high-temperature applications. However, the lower strength and strength-ductility trade-off in bulk MAX phases still pose an enormous challenge arising from the large ratio of c/a lattice parameters and less activated slips. Here, nanocrystalline Cr2AlC coating with high-purity was fabricated using a hybrid arc/sputtering technique with subsequent thermal annealing. Cylindrical micropillar compression test was conducted by FIB milling to identify the mechanical properties of the coating under deformation. The stress-strain curves demonstrated that an ultrahigh compressive strength of 5.3 GPa with strain beyond 12.5% was surprisingly achieved for Cr2AlC coating, which was 5 times larger than all the reported bulk MAX phases before. Specifically, the extraordinary ductility at RT is ascribed to the synergy of the fundamental basal slip, additional non-basal slip and deformation twinning stimulated by ultra-refinement effect of nano-crystalline Cr2AlC coating.

Prediction of concrete anchor pull-out failure using cohesive zone modeling

Concrete anchor pull-out failure is predicted using the cohesive zone-based finite element analysis. For anchor pull-out tests, two sets of concrete specimens are prepared according to the curing temperatures. The displacement of an anchor steel bar is measured using the digital image correlation technique, and the cone failure surface is reconstructed using a 3D scanner. For each test set of concrete specimens, material properties such as the fracture energy, compressive strength, tensile strength, and elastic modulus are obtained from the three-point bending, cylindrical compression and indirect tension tests. Based on the measured material properties, the cohesive zone-based finite element analysis captures the load–displacement relationship of the anchor pull-out and three-point bending tests without the calibration of material properties. The experimental results demonstrate that the fracture energy is an essential material property to predict the concrete anchor pull-out failure, and thus the cohesive zone-based finite element analysis can provide accurate prediction of the anchor pull-out failure.

Characterization of high-strength concrete under monotonic and fatigue mode II loading with actively controlled level of lateral compression

The fatigue behavior of plain concrete has been studied for decades, usually under compressive or tensile loading. Shear loading (mode II) has been almost completely neglected in the past. In contrast to cylindrical compression tests, this type of loading offers the advantage of precise load determination and a small, well-defined fracture surface. This paper presents a comprehensive experimental campaign of 66 shear tests, which was conducted to systematically investigate the monotonic, cyclic, and fatigue response of high-strength concrete under mode II loading. Since the material behavior under shear stress is strongly dependent on the concurrent lateral compressive stress, a new test setup was developed which allows simultaneous control of compressive and shear loading. One potential utilization for these shear fatigue tests is the validation of a promising hypothesis that suggests that the development of fatigue damage in concrete at subcritical load levels is governed by a cumulative measure of shear sliding. The qualitative influence of the lateral compressive loading on the displacement and damage development, fracture behavior, and fatigue life is analyzed and discussed. The test results indicate that there is no influence of the lateral compressive load level on the shear fatigue life, as long as the increase in shear strength is considered. Furthermore, concrete under mode II loading seems to have a longer fatigue life than concrete in standard cylindrical specimens under compressive loading.

THE INFLUENCE OF CHEMICAL COMPOSITION AND HEAT TREATMENT ON THE MECHANICAL PROPERTIES AND WORKABILITY OF THE ALUMINIUM ALLOY EN AW 5454

The influence of chemical composition and heat treatment on the mechanical properties and formability of the selected commercial aluminium alloy EN AW 5454 was investigated. The main properties of alloy 5454 from the AA 5xxx series are very good corrosion resistant and has good formability. From the cast slab a 50 mm thick slice was taken in the width cross section in the slab centre. One half of the slice was homogenised for 10 hours at a temperature of 530 °C. The cast and homogenised samples were investigated using light and scanning electron microscopy. For the study of the influence of the heat treatment, samples in the as-cast state were annealed in the laboratory furnace at a temperature of 530 °C for 4, 6, 8, 10 and 12 hours. To study the influence of chemical composition, four different samples were prepared: the first without additions, the second with an addition of 1 wt% Mn, the third with 3 wt% Mg and the fourth with an addition of both elements, Mn and Mg. The XRF analyses confirmed the desired chemical composition of all four produced alloys. Half of each alloy’s sample was homogenised at the same temperature and time as the base alloy in the as-cast state. The hot deformation behaviour of the different alloys was investigated using cylindrical hot compression tests performed on a Gleeble 1500D thermo-mechanical simulator. By comparing flow curves a high influence of the thermo-mechanical parameters on the alloy formability can be seen. The alloy has good workability and with the addition of Mn and Mg, the stress values are higher than those of the base alloy.

Correlating ultrasonic pulse velocity and compression resistance of dry concretes at 54 kHz and 500 kHz

Nondestructive tests applying ultrasound in concrete is used for more than halfcentury. However, the difficulties in making transit time measurement in heterogeneous media have limited the spread use of these applications. The objective of this work is to present a metrological protocol to determine the correlation between the compressive strength of concrete specimens with about 1 year of cure with their respective longitudinal ultrasonic pulse velocity (UPV). From excitation signals sent through a tunable square wave using the direct transmission method, two pairs of transducers with central frequencies of 54 kHz and 500 kHz were used. UPV is determined by the relation between the length and the propagation time of flight the waveform travels within the concrete test specimens. The pieces were constructed according to ABNT NBR 5738:2015 (Concrete – Procedure for molding and curing of concrete specimens) and tested for compression according to ABNT NBR 5739:2007 (Cylindrical specimen compression test – Method of the test). The preliminary results obtained discloses a coherent increase in UPV and concrete strength. Moreover, the highest frequency leads to higher UPV. With the findings presented in this paper, it is possible to define a dual-frequency nondestructive ultrasound method to evaluate concrete resistance more reliable than the traditional approach.

Evaluating Applicability of ASTM C 928 Approach in Assessing Adequacy of Patch Repair of Bridge Piers

Severe environmental conditions in many parts of Iran could adversely affect infrastructures, especially bridge piers. This research evaluates the efficiency of fiber-reinforced polymer-modified self-compacting concrete in patch repair of bridge piers. The efficiency of this material for repair has been verified using ASTM C 928 and a novel testing method (patch test) that uses a cylindrical compression test simulating indirect force transfer from old (existing) concrete to new (patch repaired) concrete. To investigate the efficiency of self-compacting concrete in patch repair and derive the correlation between bond strength and patch strength, two sets of specimens have been included in the experimental program. These include 24 and 27 specimens which are prepared for patch and slant shear tests, respectively. Test results show significant improvement in strength due to use of polymer modified and fiber reinforced self-compacting concrete in slant shear tests, where strength enhancement as much as 50% (compared to undamaged specimens) was observed. Meanwhile, in the patch tests, repaired specimens are only able to barely exceed the original strength of undamaged specimens. In the slant shear tests, the use of polymer is very effective in increasing bond strength and using fibers reduces observed variation in the strength of repaired specimens. Considering force path in the patch repair and regardless of materials used for repair, the results show that judging the efficiency of the repair method based on the slant shear test, as proposed by ASTM C 928, in the case of patch repaired elements could be misleading.

Determination of Forming Behaviour of EN AW-6060 by Different Testing Methods under Cold Bulk Forming Conditions

The description and modelling of the forming behaviour is essential for the numerical prediction of material flow and the applied forming force. A representative stress state as well as comparable strain rate and temperatures should be considered during material characterization. In the presented investigations, an extruded aluminium alloy (EN AW-6060 T6) was formed for different compression tests with diverse specimen geometries (cylinders, discs, flat rings, cuboids) and compared with the tensile and torsion tests under the same forming conditions and with one and the same initial microstructure with an average grain size of 50 µm. To ensure that no microstructural changes during the deformation process (recrystallization) affect the measurement results due to load-related material anomalies, all tests for the material characterization were started at room temperature. The comparison is based on the cylindrical compression test, because this is standardised for room temperature (DIN 50106) and, due to the compressive stress, is the most suitable material description for bulk forming processes. However, in the stacked compression tests without additional guide elements, a much higher friction between the layers is required than between the workpiece and the tool, so that the deformation is not concentrated on the centre of the specimen (with regard to height) and the middle layers won’t get out due to high tangential stresses. By consideration of these conditions the stacked tests are comparable to the cylindrical compression test. However, the friction between material and die must be taken into account for compression tests as well as the resulting forming heat when calculating the flow curve. Based on this, the forming behaviour can be modelled according to various flow curve approaches for cold forming processes. In general, it was found that all flow curves of the tensile tests, torsion tests and the compression test were in the range of ± 7.5 % based on the cylinder compression test.

Deformation inhomogeneity due to sample–anvil friction in cylindrical compression test

Abstract Finite element (FEM) analysis was used to systematically evaluate the inhomogeneity of deformation in cylindrical samples with various sample−anvil friction coefficients, m. It was found that the level of friction strongly influences the deformation homogeneity, which increases significantly with the friction coefficient although the overall geometry of the samples almost remains the same when m>0.4. The position, at which the effective strain along the maximum radial direction in a compressed sample is equal to the equivalent strain of the sample, does not vary greatly with respect to both equivalent strain of the sample and m. Hardness measurements of compressed cylindrical 5056B Al alloy samples revealed a change of effective strain distribution similar to that revealed by FEM analysis. There exists a quantitative relationship between the hardness and the effective strain if no recrystallization or recovery occurs during the compression process.

A computational investigation of Equal Channel Angular Pressing of molybdenum validated by experiments

Equal Channel Angular Pressing (ECAP) is a metal forming process which is commonly used to refine grain structure in metals. The process involves pushing a billet, under high pressures, through a curved channel. Metal forming of molybdenum necessitates high forming temperatures so as to sufficiently lower the flow stress and increase ductility. These high temperatures are greater than the maximal temperature of the steel tools which are heated to a lower temperature then the billet. As a result great thermal gradients may develop during the forming process.In this study, the thermo-mechanical coupling between the temperature and deformation fields in ECAP of molybdenum was investigated using a computational/experimental methodology. First, the flow stress of molybdenum and copper (used as a dummy-block in the ECAP process) and the friction conditions with the steel tools at different temperatures were determined using cylindrical and ring compression tests in conjunction with an iterative coupled finite element analysis. Finally, a multi-stage finite element model of molybdenum ECAP was developed and validated by comparison to experiments. The computational results show that, in each pass, large temperature gradients develop across the specimen. While material points at the front and back of the billet may undergo similar equivalent plastic strains they deform at very different temperatures of T = 600 °C and T = 480 °C respectively. As a result, even after a single pass, each material point may have undergone a very different thermo-mechanical process. These differences in thermo-mechanical histories may lead to different microstructural changes along the specimen.

Elastic‐viscoplasticity modeling of the thermo‐mechanical behavior of chalcogenide glass for aspheric lens molding

AbstractChalcogenide glass (ChG), as an alternative material in place of single‐crystal germanium, is increasingly used in thermal imaging, night vision, and infrared guidance systems, etc., owing to their excellent formability through precision glass molding (PGM). The deformation mechanisms of these glasses at the molding temperature involve elasticity, plasticity, and viscous flow, which call for a new theoretical model to assist the design of PGM process. This paper investigates the thermo‐mechanical properties of Ge22Se58As20 at the temperature above its softening point and establishes a new elastic‐viscoplasticity model to describe its thermo‐mechanical behaviors. After determining the model parameters through cylindrical compression tests, the new constitutive model is implemented in finite element method (FEM) of PGM to form an aspheric ChG lens. And the agreement of displacement‐time curves between experimental and simulation results exhibit the validity of the proposed elastic‐viscoplastic constitutive model.

Modified compact tension specimen for experiments on cement based materials: comparison of calibration curves from 2D and 3D numerical solutions

The evaluation of fracture mechanics parameters of materials has become very important part of considering the condition of older constructions as well as properties of newly developed materials. This contribution focuses on a numerical simulation and a calculation of fracture mechanical properties of modified compact tension test configuration. It is possible to prepare the specimens used for this test very easily from a drilled core or from specimens used for cylindrical compression test. The focus of contribution is to compare selected outputs from numerical solution of 2D (plane strain conditions) with 3D models. Particularly, the determination of the influence of 2D and 3D model on the calibration curves for selected fracture mechanics parameters is of interest. Finite element software ANSYS was used for the numerical analysis.

High-Temperature Deformation of Inconel 718PlusTM

Since its introduction in 2003, alloy 718PlusTM spurred a lot of interest owing to its increased maximum service temperature over conventional Inconel 718 (704 °C versus 650 °C), good formability, and weldability together with its moderate cost. Understanding the high-temperature deformation characteristics and microstructural evolution is still of interest to many. It is known that the service performance and hot-flow behavior of this alloy are a strong function of the microstructure, particularly the grain size. To develop precise microstructure evolution models and foresee the final microstructure, it is important to understand how and under which forming conditions softening and precipitation processes occur concurrently. In this work, the softening behavior, its mechanisms, and the precipitation characteristics of 718PlusTM were investigated in two parallel studies. While cylindrical compression tests were employed to observe the hot-flow behavior, the precipitation behavior and other microstructural phenomena such as particle coarsening were tracked via hardness measurements. A precipitation–temperature–time (PTT) diagram was reported, and modeling of the flow curves via hyperbolic sine model was discussed in the light of the PTT behavior. Both “apparent” approach and “physically based” approach are implemented and two different sets of parameters were reported for the latter. Finally, recovery and recrystallization kinetics are described via Estrin–Mecking and Bergstrom, and Avrami kinetics, respectively.

Plastometric Testing of Rheological Properties of 5083 and 5754 Aluminium Alloy

The paper present a method for determining the real steel work-hardening curves based on the cylindrical specimen compression test. The subject of testing were 5083 and 5754 aluminium alloy. The tests were carried out using the physical simulator of metallurgical processes GLEEBLE 3800 (Figure 1a) for the temperature range of 400 ÷ 560 °C and the strain rate range of 0,1 - 1,0s-1. Based on plastic deformation parameters recorded during the experiment, mathematical processing, that is the digital filtration and approximation of the obtained testing results, will be performed. Then, using the inverse method, the actual values of the coefficients of the numerical models for the rheological properties of the tested materials will be determined.

The Influence of Graded Concrete Strength on Concrete Element

The integrated use of concrete in combination with reinforcement has been acknowledged as a versatile material for structures. The resulting concrete components, whatever their size and shape, are customary assumed to have uniform compression strength and identical mechanical properties over the entire structural component. This contradicts the reality, since in practice the mixing and casting of fresh concrete creates disparities in the mixture and the material composition. The relatively heavier components, i.e. the coarse aggregates, tend to sink to the bottom of the cast, while on the upper surface, however the attempt, bleeding will occur. Further, the concrete surface exposed to the air will undergo a higher evaporation rate when compared to the layers not in direct contact with the air. Also, a relative low surface-area-to-volume ratio will experience a slower evaporation rate when compared to the areas with a higher ratio, the more intense the evaporation, the greater the risk for micro crack formations, and propagation. This research work is aimed to evaluate the actual condition of a relatively deep concrete element, and look into the presence of a gradation in terms of the concrete compression strength. Further, the study was conducted to describe the influence of compression strength gradation as function of element dimensions. For this purpose; two specimen‘s panels sized 60×60×20cm casted, cured and tested to obtain their compression strength at a variation of layers. The panels were tested at the age 28 days. The testing method involved the rebound hammer readings, the UPV measurement and the direct cylindrical compression tests, performed on specimen's, core drilled from the test panel.

Mechanical response of nonwoven polyester fabric/epoxy composites at cryogenic temperatures

In this work, we characterize the cryogenic mechanical response of nonwoven polyester/epoxy composites for high temperature superconducting devices. The test specimens were produced from the composite cylindrical components, and tension, compression and flexure tests were performed at room temperature and liquid nitrogen temperature (77K) to evaluate the elastic and strength properties of the composites. The failure characteristics of the composites were examined by microscopic observations of failed specimens. The temperature dependence and anisotropy of the composite properties were discussed.

Development of Localized Deformation in AA 2024-O

An experimental study is presented to (1) quantify the rate-sensitive mechanical response and (2) examine the localized deformation behavior under an applied temperature gradient in the alloy AA 2024. Isothermal flow stresses are obtained at temperatures from −100°C to 495°C and strain rates from 10−2/s to 10−5/s using routine compression tests and a novel cyclic test, which expedites the characterization. The material displays two distinct kinetic responses with both being amenable to localization phenomena. The lower temperature/high strain rate regime displays a rate-insensitive yield with Stage III/IV work hardening. At higher temperature/low strain rates, a rate-sensitive response with little work hardening is observed. In order to relate the material constitutive behavior to the development of localized deformation, a temperature gradient test is performed wherein temperature differences of approximately 30°C are enforced between the top and bottom surfaces of a cylindrical compression test specimen. Deformation heterogeneity developed in the two distinct regimes of material response is illustrative of warm and hot working conditions typical of industrial processes, such as rolling.