Cube Compression Research Articles

Experimental Investigation of UHPFRC Cube and Cylinder Compression Test at Elevated Temperature

The present paper focuses on compressive strength of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) cube and cylinder under compression testing machine, the experimental determination of test results shows +5% variation in compressive strength, differs from normal concrete +20% the ascending in strength development at an increased age under an elevated temperature of the material is identified with addition of hooked end steel fiber. In this study, the optimized mix design developed and the conversion ratios determined to develop relationship between cube and cylinder. The comparison between mean compressive strength ratio for cube and cylinder has been presented to determine high compressive strength. The research work is carried out to achieve enhanced target compressive strength 180 N/mm2.

Comparative analysis of results from experimental and numerical studies on concrete strength

Some results of numerical experiments of testing concrete cubes and prisms on unconfined compression, and the comparison of results obtained with experimental and specified data, are presented in the article. When performing calculations of structures in a nonlinear setting, it is very important to choose adequate deformation diagrams or material models. Because of the fact that there are no instructions how to use the diagrams of concrete and armature deformation in collaboration of steel and concrete, the simulation of reinforced concrete structures by finite elements of the same type without any assumptions is impossible. Numerical experiments have been performed in the LS-DYNA software package. This software package allows simulating the collaboration of concrete and steeling with the help of three-dimensional (for concrete) and rod (for the reinforcement) finite elements. As samples, a cube and a prism with dimensions of 150×150×150 mm and 150×150×600 mm, respectively, have been taken. The samples are simulated by solid finite elements. For the simulation of concrete, the non-linear CSCM (Continuous Surface Cap Model) material is used. The tests were carried out with samples of the following classes of concrete as for cylinder compressive strength: C12, C16, C20, C25, C30, C35. This corresponds to the following classes of cube compression strength: B15, B20, B25, B30, B37, B45. The tests have been carried out considering the friction coefficients between the plates of a testing machine, and a sample. The performed researches have shown that the destruction nature of the samples in a numerical experiment corresponds to the failure nature in real tests. The investigated model of CSCM concrete can be used in the calculation of concrete and reinforced concrete structures with acceptable accuracy for main classes of concrete.

Effect of Fine Food Mineral Dosage on the Properties of Cemented Backfill Material

Properties of Cemented Backfill Material (CBM) are highly affected by the gradation of food mineral the main components of the material. This study is concluded that with the increase of fine food mineral rate, the slump and divergence of fresh mixture increase firstly and then decrease and the maximum values were got at 50%, the bleeding rate approximate linear decrease. Cube compression strength for different ages decrease firstly and then increase with the increase of fine food mineral dosage, however, shrink ratio shows opposite trend, the maximum for the former and the latter are obtained at 40% and the variation of porosity explain those trend. Based on tests, the slump, slump extension, bleeding rate, cube compression strength and shrinkage of different ages were determined to evaluate the workability, mechanical property and deformation properties and the porosity was measured by mercury intrusion porosimeter to explore the relationship between the dosage of fine food mineral and the properties of binder backfill material.

Comparison of solid and fluid constitutive models of bone marrow during trabecular bone compression

The mechanical environment and mechanobiology of bone marrow may play essential roles in bone adaptation, cancer metastasis, and immune cell regulation. However, the location of marrow within the trabecular pore space complicates experimental measurement of marrow mechanics. Computational models provide a means to assess the shear stress and pressure in the marrow during physiological loading, but they rely on accurate inputs for the marrow and the physics assumed for the interaction of bone and marrow. Elastic, viscoelastic, and fluid constitutive properties have all been reported from experimental measurements of marrow properties. It is unclear whether this ambiguity reflects the various length-scales, loading rates, and boundary conditions of the experiments, or if the material models are sufficiently similar as to be interchangeable. To address this question, we analyzed both the mean shear stress and its spatial distribution induced in marrow during compression of trabecular bone cubes when using linear elastic, neo-Hookean, viscoelastic, and power-law fluid constitutive models. Experimentally reported parameters were initially applied for all four constitutive models, resulting in poor agreement. The parameters of the soft solid models were calibrated by linear interpolation so that the volume averaged shear stress agreed with the fluid model for each, but this could only be accomplished on a specimen-by-specimen basis. Following calibration, the root-mean-squared (RMS) difference between the solid and fluid constitutive models was still greater than 26% even when the overall mean shear stress was in close agreement, indicating that the spatial distribution of stress is also sensitive to the constitutive model. As such, the choice of constitutive model should be backed by a strong rationale, and results should be interpreted with care.

Field testing the strength of thin-layer mortars using the pull-out method

Reinforced steel bar (rebar) mesh and thin-layer mortar are applied to reinforce sintered clay brick walls in a construction site. Their strengths are measured using the pre-installed pull-out method, the post-installed pull-out method and the standard cube compression strength test. Nine strength grades of cement mortars, namely, M10, M15, M20, M25, M30, M35, M40, M45 and M50, are chosen for the test; the pre-installed and post-installed pull-out tests consist of 54 samples of each. By fitting the experimental results, a formula for the compressive strength of the thin-layer mortar for the pre-installed and post-installed pull-out tests is developed. The regression function is validated and an interval prediction of the specific compressive strength for the pre-installed pull-out test is proposed. This study provides a basis for wider application of the pull-out test for thin-layer mortar and the establishment of its technical standards.

Hybrid effects of carbon fibers on mechanical properties of Portland cement mortar

This study investigates the effects of carbon fiber with different sizes on the mechanical properties of Portland cement mortar through laboratory testing. To achieve the goal, Portland cement mortars reinforced with hybrid-sized carbon fibers were tested for potential improvement in mechanical properties. The sizes of carbon fibers used in the study include micro-length (in micrometers), macro-length (in millimeters), and a combination of both. The properties of the mortar mixes were evaluated based on the results from indirect tension test, semicircular notch fracture test, mortar cube compression test, as well as unit weight and specific gravity tests. The laboratory test results show that the hybrid fiber mix exhibited superior tensile performance to the microfiber mix. Although all three types of fiber reinforcement improved the pre-peak load energy absorbing capacity of the mortar, only hybrid fiber blend improved the mortar’s fracture resistance. The test results also showed that the hybrid fiber mix had lower air-to-cement mortar ratio than the macrofiber mix.

Experiment Research on Mechanical Properties and Penetration Performance of UHMWPE Fiber Concrete

The basic mechanical properties and penetration performance of a new type of fiber concrete reinforced by UHMWPE fiber were experimental investigated. The strengths of the cube compression, splitting tensile and beam bending of this FRC with four kinds of fiber volume fraction (FVF) was researched firstly. Then, the penetration tests for the FRC with FVF of 0.8% were then conducted. The results show that the UHMWPE fiber is of excellent effects to improve the tension strength and toughness of concrete. The penetration depth and cratering area of the FRC by bullet penetration are decreased obviously compared with plain concrete which testifies the remarkable effect of this kind of fiber on enhancing penetration resistance of concrete. Last but not least, the application prospect and field of UFRC were discussed.

Numerical Simulation of Combined Aggregate Concrete Cube Compression Test

By the submicroscopic analysis, the combined aggregate concrete is regarded as a three-phase complex material, composed of light aggregate, common aggregate and mortar. APDL program is developed to generate two-dimension aggregate structure, the radius and position of aggregate distribute randomly. Using the Boolean operation, the light aggregate, common aggregate and mortar is meshed. On the basis, the loading process of combined aggregate concrete cube is studied. It would provide reference for mechanical property analysis of combined aggregate concrete.

Orthogonal Test Research on Compressive Strength Size Effect of ECC

Engineered fiber reinforced cementitious composite (ECC) can significantly improve the seismic performance and durability of concrete structures, which has pseudo strain hardening and multiple cracking performances. Through 32 groups of 192 specimens for compressive strength of ECC, the orthogonal test study on the cube compression failure process, and further research on water binder ratio, fiber content by volume, fly ash content and sand binder ratio of 4 kinds of factors on the size effect of ECC cube compressive strength. The test result shows that: PVA fiber content increases, ECC compressive toughness is improved obviously; water binder ratio and fiber content are the main factors which affect the ECC compressive strength and size effect. When water binder ratio decrease, the compressive strength of ECC materials improve and size effect coefficient increase. Fiber content increase, the compressive strength of test block increase and the size effect coefficient increase. Through the bending tests, we know that: the fiber content by volume increases, the ECC flexural strength of the composite increases gradually.

Deterministic Clustering of Incompatible Test Cubes for Higher Power-Aware EDT Compression

The embedded deterministic test-based compression uses cube merging to reduce a pattern count, the amount of test data, and test time. It gradually expands a test pattern by incorporating compatible test cubes. This paper demonstrates that compression ratios can be order of magnitude higher, if the cube merging continues despite conflicts on certain positions. Our novel solution produces test clusters, each comprising a parent pattern and a number of its derivatives obtained by imposing extra bits on it. In order to load scan chains with patterns that feature original test cubes, only data necessary to recreate parent patterns as well as information regarding locations and values of the corresponding conflicting bits are required. A test controller can then deliver tests by repeatedly applying the same parent pattern, every time using a different control pattern to decide whether a given scan chain receives data from the parent pattern, or another pattern is used instead to recover content of the original test cube. Compression of incompatible test cubes preserves all benefits of continuous flow decompression and offers compression ratios of order 1000× with encoding efficiency much higher than 1.0. We also demonstrate that test clusters make it possible to deliver test patterns in a flexible power-aware fashion. This framework achieves significant reductions in switching activity during scan loading as well as additional test data volume reductions due to encoding algorithms employed to compress parent and control vectors.

A top-down approach for compressing data cubes under the simultaneous evaluation of multiple hierarchical range queries

A novel top-down compression technique for data cubes is introduced and experimentally assessed in this paper. This technique considers the previously unrecognized case in which multiple Hierarchical Range Queries (HRQ), a very useful class of OLAP queries, must be evaluated against the target data cube simultaneously. This scenario makes traditional data cube compression techniques ineffective, as, contrary to the aim of our work, these techniques take into consideration one constraint only (e.g., a given storage space bound). The result of our study consists in introducing an innovative multiple-objective OLAP computational paradigm, and a hierarchical multidimensional histogram, whose main benefit is meaningfully implementing an intermediate compression of the input data cube able to simultaneously accommodate an even large family of different-in-nature HRQ. A complementary contribution of our work is represented by a wide experimental evaluation of the performance of our technique against both benchmark and real-life data cubes, also in comparison with state-of-the-art histogram-based compression techniques.

Enabling OLAP in mobile environments via intelligent data cube compression techniques

The main drawbacks of handheld devices (small storage space, small size of the display screen, discontinuance of the connection to the WLAN etc) are often incompatible with the need of querying and browsing information extracted from enormous amounts of data which are accessible through the network. In this application scenario, data compression and summarization have a leading role: data in a lossy compressed format can be transmitted more efficiently than the original ones, and can be effectively stored in handheld devices (setting the compression ratio accordingly). In this paper, we introduce a very effective compression technique for multidimensional data cubes, and the system Hand-OLAP, which exploits this technique to allow handheld devices to extract and browse compressed two-dimensional OLAP views coming from multidimensional data cubes stored on a remote OLAP server localized on the wired network. Hand-OLAP effectively and efficiently enables OLAP in mobile environments, and also enlarges the potentialities of Decision Support Systems by taking advantage from the "naturally" decentralized nature of such environments. The idea which the system is based on is: rather than querying the original multidimensional data cubes, it may be more convenient to generate a compressed OLAP view of them, store such view into the handheld device, and query it locally (off-line), thus obtaining approximate answers that are suitable for OLAP applications.

Inverse analysis for identification of rheological and friction models in metal forming

The paper deals with application of the inverse analysis to the identification of friction and rheological models in metal forming. The direct model based on the finite element approach and the inverse algorithm are described. The method is validated by performing the inverse computations for different plastometric tests: uniaxial compression, ring compression, cube compression, plane strain compression and channel test. The analysis concerns both hot tests and room temperature tests. It is shown in the paper that, in general, when inverse analysis is applied the results of identification are insensitive to the type of the test, sample dimensions etc. This observation is not valid for the channel test, in which constrain of spread fosters initiation of micro-shear bands and leads to a decrease of the flow stress. Parameter sensitivity analysis is the objective of the second part of the paper. Two aspects of sensitivity are considered. The first is evaluation of the sensitivity of the output (measured) parameters of the tests with respect to rheological and friction parameters. This analysis shows that the loads are most sensitive to the rheological parameters in the uniaxial compression and the shape of the sample is the most sensitive to friction in the ring compression. The second aspect of the analysis focused on evaluation of sensitivity of the results of the inverse analysis with respect to the coefficients, which are assumed in the calculations. It is observed that the plane strain compression test is the least sensitive to the errors in evaluation of the friction coefficient. On the other hand, when friction coefficient is identified, the ring compression is almost not sensitive to the evaluation of the flow stress of the material. Various optimization techniques were used in the analysis and efficiency of the methods is compared. It is emphasized that drawing the general conclusion regarding the best optimization strategy for the inverse analysis is difficult. Nevertheless, some recommendations are given in the paper. Application of the multicriterion optimization is one of the possible efficient approaches.

Advanced SQL modeling in RDBMS

Commercial relational database systems lack support for complex business modeling. ANSI SQL cannot treat relations as multidimensional arrays and define multiple, interrelated formulas over them, operations which are needed for business modeling. Relational OLAP (ROLAP) applications have to perform such tasks using joins, SQL Window Functions, complex CASE expressions, and the GROUP BY operator simulating the pivot operation. The designated place in SQL for calculations is the SELECT clause, which is extremely limiting and forces the user to generate queries with nested views, subqueries and complex joins. Furthermore, SQL query optimizers are preoccupied with determining efficient join orders and choosing optimal access methods and largely disregard optimization of multiple, interrelated formulas. Research into execution methods has thus far concentrated on efficient computation of data cubes and cube compression rather than on access structures for random, interrow calculations. This has created a gap that has been filled by spreadsheets and specialized MOLAP engines, which are good at specification of formulas for modeling but lack the formalism of the relational model, are difficult to coordinate across large user groups, exhibit scalability problems, and require replication of data between the tool and RDBMS. This article presents an SQL extension called SQL Spreadsheet , to provide array calculations over relations for complex modeling. We present optimizations, access structures, and execution models for processing them efficiently. Special attention is paid to compile time optimization for expensive operations like aggregation. Furthermore, ANSI SQL does not provide a good separation between data and computation and hence cannot support parameterization for SQL Spreadsheets models. We propose two parameterization methods for SQL. One parameterizes ANSI SQL view using subqueries and scalars, which allows passing data to SQL Spreadsheet. Another method presents parameterization of the SQL Spreadsheet formulas. This supports building stand-alone SQL Spreadsheet libraries. These models are then subject to the SQL Spreadsheet optimizations during model invocation time.

Incremental maintenance of quotient cube based on galois lattice

Data cube computation is a well-known expensive operation and has been studied extensively. It is often not feasible to compute a complete data cube due to the huge storage requirement, Recently proposed quotient cube addressed this fundamental issue through a partitioning method that groups cube cells into equivalent partitions. The effectiveness and efficiency of the quotient cube for cube compression and computation have been proved. However, as changes are made to the data sources, to maintain such a quotient cube is non-trivial since the equivalent classes in it must be split or merged. In this paper, incremental algorithms are designed to update existing quotient cube efficiently based on Galois lattice. Performance study shows that these algorithms are efficient and scalable for large databases.

A method of calculating the mechanical properties of nanoscopic plant cell wall components from tissue properties

Biological tissues are made from nano-composite materials and given the recent interest in manufacturing synthetic nano-composites an analysis of natural nano-composites seems a worthwhile exercise. There is also potential for extracting natural nano-fibres and using them as reinforcements in other materials. In this paper a hierarchical mechanical model is formulated to describe potato tuber tissue and the model is used to back calculate the properties of cell wall nano-fibres. The model contains two structural levels, the cell structure and the cell wall structure. Material properties are assigned at the level of cell wall microfibrils (nano-composite fibres). Force deflection data from the compression of cubes of potato tissue were fed into the model and the properties of the cell wall microfibrils predicted. The modulus was found to vary with strain, but had a maximum value of 130 GPa, which is close to predictions from theoretical chemistry for the stiffness of cellulose microfibrils. At 8% wall strain (the value at which failures were suspected to begin), the stress was predicted to be 7.5 GPa which is also close to theoretical chemistry predictions for the strength of cellulose microfibrils. The large strains and decreasing stiffness indicate the influence of polymers other than cellulose.

Pairwise strength relationships of cortical and cancellous bone in human femur: an autopsy study.

To analyze the mechanical properties of cortical and cancellous bone in the femur and relate them to bone mineral, we retrieved 14 pairs of femurs from elderly subjects at autopsy. Bone mineral was measured by quantitative single-energy computed tomography. Significant associations were found between two types of cortical bone mechanical tests, three-point bending and pull-out of screw, one performed on the right and the other on the left femur. Similarly, pairwise associations were found between the mechanical tests of cancellous bone, punch and cube compression, one performed on the right and the other on the left femur. Also, all mechanical tests correlated with bone mineral as determined by quantitative single-energy computed tomography. In general, bone mass measures correlated better with bone strength than did bone density measures. However, the cortical and cancellous bone mechanical properties were not interrelated, which suggests a separate regulation of the strength of these two types of bone. Bone mineral may not only have importance for the occurrence of fractures; it should be considered as an important factor in the fixation of fragile bone.

Failure of rocks under tensile conditions

This paper examines, theoretically and experimentally, a number of systems in which extension failures occur under applied compressive loads. These are (i) compression of a circular cylinder along two diameters or by three symmetrically placed line loads (ii) diametral compression of spheres and cubes (iii) bending of circular plates. In all these cases, one principal stress is tensile over a portion of the body and failure occurs in this region: in many cases the calculated maximum tensile stresses in the region are of the order of the uniaxial tensile strength of the material. For circular plates, as for other cases of inhomogeneous stresses, they are higher. Many of these systems are related immediately to the crushing of single particles or aggregates of particles.