Influence Of Test Method Research Articles

Explaining the spread in measurement of PDMS elastic properties: influence of test method and curing protocol.

Accuracy in the measurement of mechanical properties is essential for precision engineering and for the interrogation of composition-property relationships. Conventional methods of mechanical testing, such as uniaxial tension, compression, and nanoindentation, provide highly repeatable and reliable results for stiff materials, for which they were originally developed. However, when applied to the characterization of soft and biological materials, the same cannot be said, and the spread of reported properties of similar materials is vast. Polydimethylsiloxane (PDMS), commonly obtained from Dow as SYLGARD 184, is a ubiquitous such material, which has been integral to the rapid development of biocompatible microfluidic devices and flexible electronics in recent decades. However, reported shear moduli of this material range over 2 orders of magnitude for similar chemical compositions. Taking advantage of the increased mechanical scrutiny afforded to SYLGARD 184 in recent years, we combine both published and new experimental data obtained using 9 mechanical test methods. A statistical analysis then elucidates the significant bias induced by the test method itself, and distinguishes this bias from the influence of curing protocols on the mechanical properties. The goal of this work is thus two-fold: (i) it provides a quantitative understanding of the different factors that influence reported properties of this particular material, and (ii) it serves as a cautionary tale. As researchers in the field of mechanics strive to quantify the properties of increasingly complex soft and biological materials, converging on a standardized measurement of PDMS is a necessary first step.

Influence of Test Method on the Determination of Tensile Strength Perpendicular to Grain of Timber for Civil Construction.

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test.

Immunogenicity of Atezolizumab: Influence of Testing Method and Sampling Frequency on Reported Anti-drug Antibody Incidence Rates.

Measurement of anti-drug antibodies (ADA) to assess the incidence of ADA in a clinical trial is a critical step in immunogenicity assessment during the development of a protein therapeutic. We developed novel graphical approaches to illustrate clinical trial ADA data for the PD-L1 inhibitor atezolizumab (Tecentriq) that included a systematic analysis of the impact of the timing of ADA sampling and ADA assay drug tolerance on reported ADA incidence. We found that approaches used across the industry for ADA incidence analysis provide a limited view of immunogenicity in oncology studies, where ADA detection may be confounded by both drug dosage and patient attrition. Moreover, these approaches can miss important temporal information about the immune response. Our results demonstrated that the methodology of ADA assessment for the atezolizumab program was specifically designed to capture most ADA responses to ensure accurate reporting of ADA incidence. We further showed that the use of sparse sampling and/or ADA test methods with insufficient drug tolerance may result in a significant underreporting of ADA incidence. We conclude that the comparison of ADA incidence between different drugs can be highly misleading and that a test method with appropriate sensitivity in the presence of the drug and a clinical sampling scheme that is aligned with ADA responses to a drug is required to accurately report ADA incidence.

Influence of Test Methods on Fuel Consumption of Heavy Trucks in China — From C-WTVC to CHTC

In order to reduce vehicle carbon emissions, the Chinese government is drafting new fuel consumption limits standard for heavy commercial vehicles. The standard will adopt new test method, which will have an impact on the results of vehicle fuel consumption. This paper compares the differences between C-WTVC and CHTC, and theoretically evaluates the impact of vehicle fuel consumption. In addition, the impact is empirically analyzed through the actual vehicle test. It is found that the heavy truck switching from C-WTVC to CHTC-HT will increase the fuel consumption by 0.2%-7.6%, and there is a positive correlation between vehicle fuel consumption and gross vehicle weight (GVW). Among them, the increase of fuel consumption is more obvious in the low speed and high speed parts of the test cycle. In order to achieve fuel consumption compliance, enterprises need to focus on low-speed and high-speed fuel consumption performance.

Influence of Test Method and Poisson’ s Ratio Effect on Pullout Performance of Anchor Bolt in Pile

The influence of load pattern and Poisson’ s ratio effect on the pullout performance of the anchor bolt, which were connected with pipe pile by core concrete, were investigated by three anchorage-beam pullout tests and one self-balanced pullout test. Theoretical and finite element analysis were also employed to explore the influence of load pattern and Poisson’ s ratio effect on the ultimate friction at the pipe-core-concrete contact surface. The results show that the load pattern and Poisson’ s ratio effect of pipe pile have a great influence on the pullout characteristics of the anchor bolt. The maximum relative displacements between core concrete and pipe pile and between anchor bolt and core concrete in self-balanced pullout test are 0.913 mm and 0.935 mm, respectively, which are significantly greater than that in anchorage-beam pullout test where the displacements are 0.292 mm and 0.500 mm, respectively. In the self-balanced test, the pipe pile is under compression and expands radially due to the Poisson’ s ratio effect. In the anchorage-beam test, on the contrary, the pipe pile is under tension and shrinks radially. As a consequence, the ultimate friction between core concrete and pipe pile in the anchorage-beam test is higher than that in the self-balanced test by 15.1% to 28.7%. Accordingly, the results of anchorage-beam pullout test are more sensible for the anchor bolt design.

Analysis of the influence of test method and properties of steel fiber addition on concrete under the three-point flexural tensile

espanolLa caracterizacion del concreto de consistencia seca con fibras de acero requiere mayores investigaciones por cuenta de las particularidades en el proceso de mezcla, moldeado y adensamiento, por lo tanto, el objetivo de este trabajo es proponer una metodologia combinada para la densificacion manual y mecanica y la caracterizacion mecanica con ensayo de traccion en una flexion en tres puntos en de cuerpos de prueba prismaticos de concreto de concreto de consistencia seca con fibras de acero. De modo cualitativo una metodologia combinada de densificacion proporciono un aspecto liso a la superficie en el cuerpo de prueba y reduccion de los vacios por el aire aprisionado. En el ensayo de traccion una flexion verifico el comportamiento de slip-softening y slip-hardening, respectivamente, para menores y mayores indices de refuerzo y volumenes teoricos. Al final se constato que el analisis de varianza del banco de datos indico mayores valores de resistencia residual para la combinacion del metodo de ensayo (RILEM), consistencia (plastica), especie (hookedend) y camino (colado en peine), cuando se hace la comparacion por asociacion cuadruple. EnglishThe characterization of steel fiber reinforced concrete with dry consistency require greater inspection the account of the particularities in the process of mixing, molding and densification, thus this paper aims to propose a methodology combined of densification by manual and mechanical means and the mechanical characterization by the three-point flexural testin prismatic dry cast steel fiber-reinforced concrete specimen. In a qualitative way, the densification-combined methodology provided a smooth surface on the specimen appearance and a reduction of voids due to trapped air. In the flexural test we verified slip-softening and slip-hardening, respectively, to lower and higher reinforcement indexes and theoretical volumes. By the analysis of variance of the results and the database we found out that there was no significant statistical difference to the analyzed residual strength for the combination of the test method (RILEM), consistency (plastic), type (hooked end) and form (glued), when the comparison is made by quadruple association.

Influence of test method on tribological property of paper

Influence of test method on tribological property of paper

Effect of Structure on Strength of Agglomerates using Distinct Element Method

Knowledge of agglomerate strength is highly desirable for compression and tableting, dissolution and dispersion and mitigation of dust formation. The behaviour of agglomerates is affected by parameters such as density, agglomerate size, primary particle size, and interparticle bond strength. The method of agglomeration influences the evolution of structure, and this in turn affects its strength. Furthermore, the methods of strength characterisation, i.e. quasi-static or impact produce different results. To understand the role of structure and the influence of test method, agglomerate failure behaviour has been analysed by the use of the Distinct Element Method (DEM). We report on our work on the simulation of the breakage of the agglomerates for different porosities and impact conditions, where the role of impact speed and angle and type of contact bonding model have been evaluated. The adhesive contact model of JKR is used to form an agglomerate. The effect of the bonding level on the strength and size distribution of the clusters released as a result of failure has been investigated. This work also evaluates the effect of structure (porosity) on the strength of the agglomerates.

Influence of test method on biodegradation of bamboo-plastic composites by fungi

The effects of differing ratios of bamboo/plastic polymers on resistance to fungal attack was assessed using two different decay test methods. Weight losses for non-treated southern pine and Carpinus betulus sapwood blocks indicated that the test conditions were suitable for aggressive decay by Gloeophyllum trabeum and Trametes versicolor. Mass losses on the bamboo/composites tended to be very low, regardless of the method employed. In general, moisture levels in the composites were extremely low although they were close to the point where fungal attack could occur when only the bamboo components were considered. The standard decay tests indicated that bamboo can be considered a suitable substitute for wood flour in wood-plastic composites.

Determination of mechanical properties of Al2O3/Y-TZP ceramic composites: Influence of testing method and residual stresses

A series of Al2O3/Y2O3-stabilized zirconia (Y-TZP) ceramic composites with different zirconia contents (5 and 40vol% Y-TZP) and fabricated by different green processing techniques (a novel tape casting and conventional slip casting) were studied. The microstructure and mechanical properties of the composites were investigated systematically, by means of scanning electron microscopy, Vickers indentation, depth-sensing nanoindentation, and single-edge laser-notched beam (SELNB) techniques. The indentation fracture method was found to be unsuitable for fracture toughness determination in this work. Reliable values of fracture toughness were obtained by the SELNB method with an almost atomically sharp laser-machined initial notch. The microstructure and mechanical properties of the ceramic composites mainly depended on the Y-TZP content. No significant differences were induced by the choice of green processing technique. The contribution of residual stresses to fracture toughness in Al2O3/Y-TZP ceramic composites was investigated. To this end, a theoretical model was applied to estimate the increase in fracture toughness due to the measured residual stresses in the samples. It was found that in this case, residual stresses were not the main factor responsible for the toughening in Al2O3/Y-TZP composites.

Cracking and load-deformation behavior of fiber reinforced concrete: Influence of testing method

The characterization of the tensile behavior of cementitious materials has been a long-standing research topic and a general consensus on how to accomplish this task has not yet been reached. Many standardized tests are available but each with different test set-up and prescriptions on the definition of measured and derived parameters, including toughness, elastic properties and strength. This paper discusses a number of test procedures for selected material properties including tension and flexure. A comparative experimental study was carried out using two distinct fiber reinforced cementitious composites with strain hardening and strain softening behavior. Digital Image Correlation was utilized in the experimental program to detect and quantify the formation of cracks. Results show that the different test methodologies valuate specific aspects of material performance. The outcome of these evaluation procedures is compared and critically analyzed.

Decay resistance of softwoods and hardwoods thermally modified by the Thermovouto type thermo-vacuum process to brown rot and white rot fungi

AbstractSoftwoods (SW, spruce and fir) and hardwoods (HW, ash and beech) were thermally modified by the thermo-vacuum (Termovuoto) process for 3–4 h in the temperature range 160–220°C (TMW160–220°C) and their fungal durability were examined in soil-block tests with two brown rot (BR,Postia placenta, Gloeophyllum trabeum) and two white rot (WR,Pycnoporus sanguineus, Phlebia radiata) fungi. SW-TMW160–220°Cwere exposed toP. placentaandP. sanguineusand HW-TMW190–220°Cto all fungal species. Considerable improvement (durability class 1–3) in decay resistance was only achieved for SW- and HW-TMW220°C. Thermal modification (TM) below 200°C influenced decay resistance negatively in case of some fungal species applied for both SW and HW. Judged by the durability class, decay resistance was higher in HW- than in SW-TMW at high TM temperature. Behavior of TM differed significantly between ash (ring-porous HW) and beech (diffuse-porous HW). A comparison between results of soil- and agar-block tests on Termovouoto wood demonstrated that the influence of testing method in terms of assignment to durability classes is not significant.

Influence of Testing Methods to Determine the Bending Modulus of Elasticity of Wood

In Brazil, the characterization of solid wood for structural design must be carried out according to the recommendations of the ABNT NBR 7190:1997 standards. Studies about alternatives to improve reliability to test methods are always relevant. Thus, the present study aims to examine the bending modulus of elasticity of samples of three wood species: Canelao ( Nectandra membranacea), Corymbia citriodora (Corymbia citriodora) and Angelim (Angelim sp). The results for Canelao and Angelim showed statistical equivalence between the methods at 5% significance level. However, for the Corymbia species, statistical differences of results for bending tests with three and four points were observed. More studies are recommended in order to investigate other wood species, different strength classes and moisture content ranges.

Crush strength of silicon carbide coated TRISO particles: Influence of test method and process variables

The influence of deposition temperature, methyl trichlorosilane (MTS) concentration, hydrogen carrier-gas flow rate and gas inlet design on the strength of silicon carbide coated TRISO particles was investigated using whole particle crushing strength. Crush strength was measured using soft aluminium anvils. For comparison a selection of particles were also measured with hard anvils. The influence of silicon carbide thickness was determined to allow for normalisation of all crush strength measurements to a crush strength at an equivalent thickness of 35μm.It was found that the strength of the underlying pyrocarbon coated particles had a significant influence on the crush strength of the silicon carbide coated particles. Deposition temperature and gas inlet design were the only process parameters that influenced the coated particle crush strength. No evidence was found for MTS concentration and hydrogen flow rate having any influence on particle crush strength.

Influence of test method used to evaluate resistance of C‐Mn steel to hydrogen induced cracking

AbstractThe presented paper deals with a comparison of test methods for evaluating the resistance of API grade X65 steel to hydrogen induced cracking (HIC). It concerned particularly the ultrasonic immersion method using an AGFA non‐destructive testing device by Krautkrämer and metallographic evaluation of the results of ultrasonic tests according to the directive NACE TM 0284. Comparison of test methods was made on the basis of established parameters of cracks, i. e. crack length ratio (CLR), crack thickness ratio (CTR) and crack sensitivity ratio (CSR). The determination of parameters in case of ultrasonic examination was performed using the pulse reflection method. Metallographic evaluations were performed always at hundred‐fold magnification on a light microscope ZEISS NEOPHOT 32. The obtained results showed that all the test methods used had very small differences between the investigated parameters.

Influence of test methods on dc flashover performance of ice-covered composite insulators and statistical analysis

Operational statistics and studies have revealed that, the reduction of insulation strength of transmission line insulators caused by icing is one of the critical reasons of the power grid faults. This paper compares of various test methods for evaluating the flashover characteristic of ice-covered composite insulators. Two types of composite insulators, i.e. FXBW-±800/530 short sample and FXBW-110/100 are investigated. The influences of various test methods on flashover performance of ice-covered insulators are studied in an artificial climate chamber. The test results revealed the influences are significant. The average flashover voltage (Uav) using even raising method is highest, followed by the 50% withstand voltage (U50%) which is corresponding to up and down method, the lowest flashover voltage (Uf.min) using Ucurve method is the third, and the maximum withstand voltage (Uws) using the maximum withstand voltage method is the lowest. Through the statistical analysis, the U50% can be estimated by Uav and σav though the estimated value Ue (Ue=(Uav-k1σav)/( 1+k2δe)). The estimated errors (Ee) are less than 1.80% in this paper. Therefore, there is an intrinsic relationship among the test results obtained by using various test methods. This simplifies selection of the appropriate test method according to the testing specific circumstances.

The influence of test method, conductor profile and substrate anisotropy on the permittivity values required for accurate modeling of high frequency planar circuits

PurposeThe purpose of this paper is to help high frequency circuit designers understand how to choose the best permittivity value for a laminate material for accurate modeling.Design/methodology/approachIn this paper, experimental measurements of the performance of simple circuits are compared to various mathematical and software models.FindingsHigher permittivity values were obtained using samples with bonded copper foil compared to samples etched free of foil. These higher values yielded better agreement between measured and modelled performance using current automated design software. High profile foil on thin laminates was found to increase the surface impedance of the conductor and change the propagation constant and apparent permittivity of the laminate by 15 percent or more. It was also demonstrated that, under some circumstances, the anisotropy of the substrate could result in differences in measured and modelled performance.Research limitations/implicationsOnly a limited number of circuit laminate materials were closely examined. Future work should include a wider variety of laminates.Originality/valueThe paper details the magnitude of the effects of test method, conductor profile and substrate anisotropy on the values of a material's permittivity best suited for circuit design purposes.

Influence of Testing Methods on Setting Time of Foam Concrete

As a porous material, foam concrete can be manufactured not only into building materials with good heat insulation performance, but also into materials with good water permeability, and by properly controlling the size and shape of the pores, the foam concrete can be used as acoustic material to meet People's increasing demand for functional materials. Therefore, the development of foam concrete has a vast potential for future market. Though the setting time of foam concrete is one of the key technical parameters for the preparation of high performance foam concrete, there is no standard method for the testing of the foam concrete’s setting time. That militates against the development of foam concrete greatly. In this paper, two methods were used to measure the setting time of foam concrete. The results show that the offset value of the foam concrete’s initial setting time measured by the two different methods increases with the increasing of foam volume adding to the foam concrete which use the Portland cement and Portland cement-mineral admixture as binder. Finally, a prefer method to test the foam concrete’s initial setting time was selected.

Chloride transport in fly ash and glass powder modified concretes – Influence of test methods on microstructure

This paper discusses the influence of rapid chloride transport test methods on the microstructure and the measured chloride penetration resistance of concretes containing fly ash or fine glass powder as partial cement replacement materials. Rapid chloride permeability (RCP), non-steady-state migration (NSSM), and steady state conduction (SSC) tests are performed on plain and modified concretes. The glass powder modified concretes demonstrate similar or lower RCP values as compared to the fly ash modified concretes of the same cement replacement level whereas the steady state conductivities are lower for the fly ash modified mixtures. The NSSM coefficients are lower for the fly ash modified concretes even when the initial conductivities are similar to those of plain or glass powder modified concretes. Chloride binding under the conditions of NSSM test, that influence the microstructure and the transport parameter, is quantified using thermal analysis and XRD patterns as well as an electrical circuit model for the impedance response. The resistance of connected pores (Rc) extracted from the model adequately captures the changes in microstructure with time and with chloride transport. The changes in Rc between the start and finish of the NSSM test also indicate microstructural alteration in fly ash modified concretes.

Influence of test method on swelling pressure of compacted clay

Swelling pressure of clays is an important parameter required for the design of a variety of structures founded on expansive soils. Out of many methods available to determine the swell pressure in the laboratory, odometer method is popular because of its simplicity. Three odometer methods are commonly used to determine swelling pressure, such as swell consolidation method (Method A), different pressure method (Method B) and constant volume method (Method C). Comparison of values obtained by the three methods shows that Method A gives highest value, Method B gives the lowest value and Method C give intermediate value. The possible reason for this difference is brought out in this paper. Experimental evidence, from permeability measurements and SEM, shows that fabric alteration from a flocculated state to dispersed state occur in Method A due to swelling under a nominal surcharge pressure. As swelling is not permitted in Method B and C, the original fabric remains the same.