Standard Testing Machine Research Articles

Wear resistance of maraging steel developed by direct metal laser sintering

This work presents wear study on maraging steel developed by additive manufacturing using Direct Metal Laser Sintering, utilizing a laser beam of high-power density for melting and fusing the metallic powders. Short aging treatment was given to the specimen prior to the wear tests. The density and the hardness of the 3D printed maraging steel were found to be better than the homogenized-aged 18Ni1900 maraging steel. The wear resistance is an important aspect that influences the functionality of the components. The wear tests in dry condition were performed on maraging steel on pin/disc standard wear testing machine. The design of experiments was planned and executed based on response surface methodology. This technique is employed to investigate three influencing and controlling constraints namely speed, load, and distance of sliding. It has been observed that sliding speed and normal load significantly affects the wear of the specimen. The statistical optimization confirms that the normal load, sliding distance, and speed are significant for reducing the wear rate. The confirmation test was conducted with a 95% confidence interval using optimal parameters for validation of wear test results. A mathematical model was developed to estimate the wear rate. The experimental results were matched with the projected values. The wear test parameters for minimum and maximum wear rate have been determined.

A REVIEW BENDING BULKLING AND FLEXURAL VIBRATIONAL ON FIBER METAL LAMINATES FOR AUTOMOBILE SECTOR

In this commitment, the effect dynamic reaction and disappointment methods of fibre–metal overlaid boards exposed to low speed sway were explored and introduced. The fibre–metal cover in this paper involved a layer of glass fibre-fortified plastics sandwiched between two layers of aluminium combination. Two distinct kinds of glass fibre-fortified plastics were utilized for the manufacture: unidirectional and woven. A genuinely broad exploratory examination was directed related to an itemized limited component examination. The examinations were led utilizing a standard drop-weight test machine and the limited component examination was done utilizing a monetarily accessible limited component programming. The aftereffects of greatest contact power, contact span and relating disappointment modes are displayed, looked at and examined in this specialized paper. Scaling impacts in the low speed sway reaction of a polypropylene based fibre metal cover (FML) structure have been examined. To choose aluminium sheet so as to with have properties like erosion obstruction, high effect and weariness quality, great toughness and dependability. To choose great holding glue for FML to defeat delaminating. The aluminium sheet is commonly treated with CH3)2CO with degreasing of material debasements.

Forecasting the strength properties of the large diameter polymer rebar based on the experimental analysis of its structure

Fiber reinforced plastic bar (FRP-rebar) is a two-component material consisting of polymer matrix (resin) and reinforcing filler (roving). Large-scale implementation of FRP-rebar and improvement of its manufacturing process have resulted in larger bar diameters. However, it is extremely complicated or even impossible to experimentally determine the mechanical properties of this kind of rebar when using standard testing machines. The reason for this is the low cross-direction strength of the rebar. The purpose of the research is to determine the elastic and strength properties of large diameter FRP-rebar by means of finite-element simulation as well as to analyze the influence of the components’ mass fractions and grooving on the mechanical properties being studied. In order to specify the parameters of the FE simulation model the authors performed some supplementary tests aimed at determining the structure of the fiber. A comparative study of the obtained numerical results against the experimental data is presented in the paper.

Methodology of dry and wet compressibility measurement

This paper describes a methodology to obtain and analyse data in composite reinforcement fabric compaction tests in dry and saturated conditions using a standard electromechanical test machine and an indirect thickness measurement method.The main goal is the identification of machine compliance sources and the understanding of its effects in typical compression tests and compression with relaxation stage tests. This methodology was used in the first international compressibility benchmark exercise promoted by NPL (National Physics Laboratory, UK) in the years 2017 and 2018. The methodology accounts for the test setup compliance and evaluates errors in fabric thickness measurements in the range of tens of microns especially during the relaxation phase. Overall, the setup compliance and data analysis strategy proved to have a significant effect on the data if not properly accounted for.

Quantitative evaluation of interfacial adhesion between steel reinforcements and self-compacting concretes, in steel/concrete composites, by indentation tests

ABSTRACTTo ensure reinforced concrete bars applications in more severe loading conditions, the contact between the steel bar and concrete must be strongly adhesive. This adhesion constitutes an important property for the use of reinforced concrete. That is why many techniques were developed with the aim of determining this property. Adhesion can be easily found out by standard pull-out test machine. However, in this work, the adhesion was measured for the first time using Interfacial Indentation test. In this work, given the lack of results obtained using the interfacial indentation test in the literature so that we can compare our results with, the alone alternative found is to compare them with those of the pull out test. Using reinforcing bars, adhesion was measured using Self Compacting Concrete (SCC) and Normal Vibrated Concrete (NVC) specimens. The impact of water-to-binder ratio variations and concrete type on steel bar/concrete adhesion has been the incentive of the present study. As a main conclusion, interfacial indentation test can be more properly represent the actual steel/concrete interface adhesion compared to the pull-out test which is a more global test.

Impact Strength of Interply and Intraply Hybrid Laminates Based on Carbon-Aramid/Epoxy Composites

Hybridization plays an important role to achieve multi-functionality for the particular composite applications. Hybrid composites allow designers to obtain desired physical and mechanical properties that cannot be provided from a single type of fiber reinforcement such as combining high strength, light weight and good impact resistance together. In this study, the effect of hybridization on the Charpy impact strength was investigated considering the aramid and carbon fiber reinforced polymer (FRP) composites. For this reason, interply, intraply hybrid composite laminates, aramid FRP and carbon FRP were manufactured by hand lay-up followed by vacuum bagging method. The composite laminates were tested according to ISO 179-1: 2010 Standard using Charpy impact testing machine. The results were given comparatively and shown that energy absorption capacity of intraply hybrid composite laminate was found better than others.

Recent Advances in Spline Couplings Reliability

Spline couplings are mechanical components widely used to transmit torque between rotating parts. Although they are well known components, critical issues such as wear damage and un haven loads affect them especially when working in misaligned conditions. Wear damage appears on engaging teeth bringing to component failures. The main way to reduce wear damage is to lubricate the engaging teeth or to apply surface coatings. In this work wear damage on spline coupling was investigated and a compound made of grease added with graphene has been tested against standard lubricants in order to find out if it may improve the wear strength of these components. Experimental tests were performed by means of both standard testing machine provided by a particular testing device and dedicated test rig, designed to perform tests with misaligned spline couplings.Preliminary results show that the presence of graphene improves the grease performance, reducing the coefficient of friction (bringing to a reduction of uneven overloads and wear).

Determination of the crack resistance curve for intralaminar fiber tensile failure mode in polymer composites under high rate loading

This paper presents the determination of the crack resistance curve of the unidirectional carbon-epoxy composite material IM7-8552 for intralaminar fiber tensile failure under dynamic loading. The methodology, proposed by Catalanotti et al. (2014) for quasi-static loading conditions, was enhanced to high rate loading in the order of about 60 s−1. Dynamic tests were performed using a split-Hopkinson tension bar, while quasi-static reference tests were conducted on a standard electromechanical testing machine. Double-edge notched tension specimens of different sizes were tested to obtain the size effect law, which in combination with the concepts of the energy release rate is used to measure the entire crack resistance curve for the fiber tensile failure mode. Digital image correlation is applied to further verify the validity of the experiments performed at both static and dynamic loading. The data reduction methodology applied in this paper is suitable for intralaminar fiber failure modes without significant delamination. Sufficient proof is given that quasi-static fracture mechanics theory can also be used for the data reduction of the dynamic tests. It is shown, that the intralaminar fracture toughness for fiber tensile failure of UD IM7-8552 increases with increasing rate of loading.

High-speed cutting of foods: Cutting behavior and initial cutting forces

The viscoelastic properties of foods determine deformation, fracture and friction during industrial cutting applications and substantially affect the cutting behavior, especially at high cutting velocity. Using a custom-built high-speed test station the cutting behavior of representative foods (either based on a protein network, plant tissues and sugar based confectionary) and food models on elastomer basis was investigated at a cutting velocity ranging from 10−4 m/s up to 10 m/s. On the basis of cutting force data and dynamic mechanical analysis performed between 1 rad/s and 100 rad/s, the cutting behavior of the systems was investigated. In general, the cutting force profiles depended on cutting velocity and could be related to deformation characteristics that were measured in dynamic mechanical analysis (except for plant tissue whose inherent composite structures seem to contribute to brittle behavior at each cutting velocity). Sugar based confectionary showed a strong rate dependence with brittle fracture and splintering in the high-speed region. For all systems except plant tissues a velocity dependent deformation cutting parameter, derived from the initial cutting forces, coincides with the power law frequency dependence of the complex modulus. This relation was used to build a model approach with which the pre-crack cutting forces at high-speed cutting velocity can be predicted with commercially available standard testing machines.

Effect of post type on the fracture resistance of endodontically treated premolars

Endodontically treated teeth (ETT) are more susceptible to fracture during mastication. The aim of our study was to investigate the fracture resistance of premolars, restored with different techniques. Eighteen human premolars, extracted for orthodontic or periodontal reasons, were used. Mesio-occlusal cavities were prepared on all of them. They were divided into 3 groups according to the restoration method: with a cemented fiber post (FP), with a cemented metal post (MP) and without a post, but restored with a fiber reinforced composite core (FRC). After thermocycling, their fracture resistance was evaluated in a standard testing machine. The results were analyzed with one-way ANOVA and Tukey Honestly Significant Difference (HSD) tests (p<0.05). The fracture modes were also determined. The MP group showed the lowest fracture resistance rates and the highest number of unrestorable root fractures. In conclusion, teeth restored with FRC cores or FP show better survival rates than those restored with metal posts.

Geometrical analysis and tensile behaviour of parts manufactured with flame retardant polymers by additive manufacturing

PurposeFlame-retardant plastics are used in critical applications, such as aircraft interior parts, when the occurrence of fire can lead to serious injury to people. However, there is a lack of related publications. The purpose of this study is to present experimental data regarding geometrical analysis, such as dimensional accuracy and surface roughness, tensile strength and elongation of parts manufactured with flame-retardant materials by additive manufacturing.Design/methodology/approachTwo additive manufacturing processes, selective laser sintering (SLS) and fused deposition modeling (FDM), were selected to manufacture the parts to be evaluated. Each process used its respective polymer, that is polyamide with flame-retardant additive (PA) for SLS and polyphenylsulfone (PPSF) for FDM. The samples consist of tensile specimens and representative parts of different products. Tensile tests were performed using standard tensile test machines, and geometrical analyses were performed using coordinate measuring machine as well as surface roughness tester.FindingsAs each material can be, in commercial machines, produced by only one process, the material selection for final products has to consider the manufacturing process as well. In general, although the FDM/PPSF process provided specimens with the highest ultimate strength, because of its strong influence by the building direction, FDM/PPSF also provided the lowest strength. SLS/PA was able to provide average strength with less dependency on the build-up direction. The geometrical analysis showed that SLS/PA presents a much smoother surface, but FDM/PPSF presented slightly better dimensional accuracy.Originality/valueThere is still lack of publications on polymers with flame resistance or flame-retardant polymers. Thus, this paper brings new technical information about processing such materials.

Design of a biaxial test module for uniaxial testing machine

A new design for a biaxial tensile testing module or fixture was developed to characterize a sheet metal specimen with a level of anisotropy. The main advantage of this fixture is the capability to perform tests in standard testing machines, besides its low-cost and easy mounting of the test specimen in comparison with other fixtures. The design was developed according to different fixture from the literature. These were analyzed by using Finite Element Analysis (FEA) software in order to identify their advantages and disadvantages as well as their behavior under loading. To validate the results from the FEA, 3D printed models were carried out, and their kinetic functionality was observed. With the resulting data new design was proposed, this was analyzed using FEA and 3D printed in order to evaluate its functionality.

Anisotropy of Mechanical Properties in a Hot‐Pressed Boron Carbide

Effects of microstructure and material properties on the mechanical behavior of hot‐pressed boron carbide are presented. The microstructure and intrinsic microstructural inhomogeneities have been characterized using scanning electron microscopy characterization techniques (SEM/EDS/EBSD). In situ mechanical characterizations of the boron carbide microstructure and its larger inhomogeneities have been performed by nanoindentation. Macroscopic dynamic and quasi‐static compressive responses have been studied in two characteristic orientations (parallel and perpendicular to the hot‐pressing direction) using a modified compression Kolsky bar setup (strain rates of /s) and standard MTS test machine (strain rates of /s). The microstructure characterization showed that boron carbide has a fine‐grained microstructure with a complex superposition of nonmetallic inclusions, such as free carbon, AlN, and BN. Nanoindentation tests conducted in three principal planes of the plate revealed an anisotropy of the mechanical properties. The compression tests revealed that the strength of this hot‐pressed boron carbide is orientation dependent. Detailed SEM analysis indicated transgranular fracture and microcracking originating at large carbon inclusions. Influences of microstructural anisotropy on the mechanical response of the material are discussed.

Biomechanics of Fractures.

This video presents the digitized, original, reel-to-reel footage of Victor Frankel's groundbreaking 1960s experiments demonstrating the viscoelastic properties and fracture mechanics of loaded bone. As can be seen, novel instrumentation was used that resulted in an easily reproducible method of controlling bone loading rates. The innovation, and associated experiments, radically advanced our understanding of the mechanisms of acute fractures and bone's response to energy. Using the "Standard Torsion Testing Machine" that he helped design, the author explains how the mechanical and functional properties of bone are affected by various defects. Examples used include an intact dog femur, a femur with a hole in the cortex, and a femur with an open section defect. Slow motion depiction allows the viewer to appreciate the potential soft tissue damage associated with bone fragmentation and how this varies with energy input. The video concludes with a demonstration of the effect of torsional motion on the vasculature. Graphs produced by the torsion tester display torque versus angular deformation plots for each experiment. These illustrate the relationship between bone structure, fracture, and energy. The x-ray contrast segment provides an example of associated arterial damage secondary to a fracture. This previously unreleased piece of orthopaedic history provides viewers with perspective on the early days of biomechanical study and an easy-to-understand tutorial on acute fracture mechanics and the role of energy in injury.

Instrumental evaluation of fabric abrasive wear using 3D surface images

Fabric abrasive wear consists of both fuzzing and pilling phenomena, which are often assessed subjectively by comparing the sample to the photographic standards. This paper introduces a stereovision system to generate the three-dimensional (3D) image of surface appearance for objective evaluation of fabric wear. The 3D information of a fabric surface obtained from the stereovision system can be used to extract the fuzzing and pilling parameters that are insusceptible to fabric structures, colors, and fiber contents. Ten types of fabrics were treated on a standard fabric abrasion testing machine (the Martindale Tester) and visually graded. From the 3D images of these fabrics, the fabric fuzziness was quantified using a set of surface roughness parameters, such as the root mean square roughness (Rq), the mean roughness depth (Rz), bearing ratio (tp), and skewness (Rsk), and the fabric pilling was measured by density (D), height (H), size (S), and area ratio (AR) of individual pills. The results from the 10 tested samples demonstrated that the 3D measurements can characterize fuzzing and pilling appearance of fabric and quantify the degree of fabric abrasive wear.

Anti-buckling System for Flat Specimens Investigations under Cyclic Tension-compression

Modern automobile and airplane structures made of sheet metals or composites require usage of thinner and stronger materials. On the other hand, manufacturers are trying to reduce production costs by shortening the fabrication processes and by application of computed simulation for forming operation. Therefore, it is necessary to better understand and more accurately investigate deformation behaviour of sheet alloys. Testing of flat specimens under compression and cyclic tension-compression within large deformation procures a lot of problems. One of them is the buckling phenomenon. A new version of the device mounted in a standard testing machine was developed and geometry of the specimen for validation of the device was proposed. Specimens of DP690 steel with nominal thickness equal to 1.6mm were investigated at ambient temperature. Tension-compression cyclic tests within a strain range ± 0.04 were executed starting in tension direction. It is shown that the results are repeatable.

Equi-biaxial tension tests on magneto-rheological elastomers

A bespoke test rig has been designed to facilitate testing of magneto-rheological (MR) elastomers (MREs) under equi-biaxial tension using a standard universal test machine. Tests were performed up to 10% strain on both isotropic and anisotropic MREs with and without the application of an external magnetic field. Assumptions regarding the material’s response were used to analyse stress–strain results in the two stretching directions. The assumptions have been verified previously by uniaxial tension tests and by simulations of the magnetic flux distribution performed using a commercial multi-physics finite element software. The MR effect, which is defined as the increase in tangent modulus at a given strain, has been studied versus engineering strain. The latter was measured optically in the experiments using a digital image correlation system. Relative MR effects up to 74% were found when the particle alignment of anisotropic MREs was oriented parallel to an applied magnetic induction of just 67.5 mT.

Dependence of Microstructure, Texture and Tensile Properties on Working Conditions in Indirect-Extruded Mg-6Sn Alloys

Abstract Dependence of microstructure, texture and tensile properties on working conditions (ram speed and initial billet temperature) in indirect extruded Mg-6wt%Sn alloys were investigated by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and a standard universal testing machine. Results show that the grain size, the recrystallization fraction and the dynamic precipitate fraction of the alloys are greatly affected by the working conditions. Their texture intensities weaken as the ram speed and the initial billet temperature increase. Tested in the different working conditions, the ultimate tensile strengths of the Mg-6Sn alloys extruded at high working temperature (controlled by initial billet temperature and ram speed) are remarkably better than those at the medium and low temperatures. The tensile properties of the alloys extruded at the high working temperature are similar to those of a commercial AZ31 alloy extruded at the low temperature, showing the possibility of the development of high speed extruded Mg alloys based on Mg-6Sn alloy.

Design and operation of a high temperature wear test apparatus for automotive valve materials

A current trend in the automotive industry is to reduce the engine size while increasing power. The valve and valve seat perform the functions of ensuring the entry of air and combustible material, the output of combustion gases and sealing during the compression and combustion processes. As a result, the pair valve and seat are the most critical components in high-efficiency engines. To ensure the robustness of their operation while providing clean combustion and low emissions, the use of the correct materials is required. The high temperatures of the exhaust gases, the velocities of the valves and the high operating pressures are several of the parameters that cause wear on the valve seats and valves. The materials used to create the valve must be characterized by good workability, high wear resistance, good mechanical strength and good fatigue and corrosion resistance at high temperatures. However, the tests applied to develop new materials are limited to lower temperatures than those expected in the next generation of combustion engines. In this study, the development of a new valve seat and valve test machine for high temperatures is presented. A comparison of the currently available designs of apparatuses for this purpose is also presented with the new proposed design. The results of testing the valve seats and valves using this new design are presented and evaluated along with the results of the standard test machines.

Bond characteristics of reinforced TMT bars in Self Compacting Concrete and Normal Cement Concrete

In its simplest form, it can be said that the resistance to separation of mortar and concrete from reinforcing steel (or other materials) with which it is in contact is called bond strength. These days different kinds of concrete are manufactured, all with different properties. But bond strength is something which is essentially a well sort after quality for any RCC structure or element. Bond strength can be easily found out by standard pull-out test machine. But in this work, the bond strength was measured using Universal testing machine (UTM) with some modified arrangements. The bond between the concrete and steel reinforcement was investigated for two different kinds of concretes. Using reinforcing bars bond strengths were measured using Self Compacting Concrete (SCC) specimen and Normal Cement Concrete (NCC) specimen. Castings of SCC specimens were carried out without compaction, while the normal concrete specimens were casted with substantial compaction and vibration. The study revealed that SCC specimens generated higher bond to reinforcing bars in comparison with NCC specimens. Secondly, the correlation between bond strength and compressive strength of NCC is more consistent. Thirdly, the results obtained with UTM were compared with the results obtained with standard pull-out test machine and they were found in permissible limits.