Falling Weight Test Research Articles

Experimental Study of Atmospherically and Infrared-Dried Industrial Topcoats

In this paper, five different solvent-borne industrial topcoats were dried with infrared (IR) radiation and under atmospheric conditions. A comparison of physical, mechanical, chemical, and electrochemical properties of differently dried topcoats was made. The results of differential scanning calorimetry (DSC), Fourier-Transform Infrared Spectroscopy (FTIR), and adhesion of a topcoat to the metal substrate (determined by the pull-off test) indicate a higher degree of crosslinking of examined topcoats, which improves the coating’s protective properties. Scratch hardness was determined by the pencil hardness test. Impact resistance was examined with a falling-weight test. Changes in the shade of the coating were examined by visual inspection and using a gloss meter. The electrochemical measurements of open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were conducted. The thermal stability of topcoats was tested by thermogravimetric analysis (TGA). The results show overall better properties of IR-dried topcoats. In addition, topcoats dry significantly faster when IR radiation is applied, which makes this drying method very interesting for industrial application.

Poliamid 11 kaplamasının termal karakteristiği, yüzey morfolojisi, mekanik ve tribolojik özelliklerin incelenmesi

The purpose of this study was to investigate the mechanical and chemical characteristics of polyamide coating by dipping in a fluidized bed system. For polyamide coating application steel test specimens were used. Test specimens, which were sprayed with primer, were cured in an oven and then coated by dipping in fluidized bed. To investigate the mechanical properties abrasion resistance, scratch, salt spray and hot oil resistance tests were performed. Furthermore to investigate the thermal characteristics of coating DSC and TGA analyses were carried out. Molecular structure of polymer coating and primer were analysed by FTIR spectroscopy. Experimental results showed that primer consists nearly 50% percentage of water, coating surface was smoother than concerning investigations in literature. Scratch resistance of coating was above 40N. Up to 1.5kg load there was no crack on coating during falling weight test. Despite using an additional load of 1kg to abrasion wheels during 5000 cycles of test polyamide coating showed fine abrasion performance. On the coation surface, there were no coating failure or deterioration failure was observed after salt spray and hot oil tests. In summary, polyamide powder coatings applied by dipping in a fluidized bed can be used in harsh corrosive environments and also this coating is suitable for mechanic parts where the mechanical strength is necessary.

Evaluation of railway trackbed moduli using the rail falling weight test method and its backcalculation model

A new falling weight test method based on the direct impact on the rail was studied and a backcalculation model was developed to estimate the moduli of the railway substructure layers. The model is three-dimensional, dynamic, and considers the superstructures. After the preliminary studies on the impact system and measurement setup on a test track, a case study was performed on a railway station track. The data were recorded using a series of linear variable differential transformers, geophones, and accelerometers during the proposed falling weight test on the rail. To establish the soil profile and better understanding of the site, geotechnical and geophysical investigation of the soil was done using in situ and conventional laboratory tests. The studies show that the rail falling weight test is feasible and leads to reasonable results. Verification of the backcalculation model with the ABAQUS finite element simulation and comparison of the backcalculated moduli with the results of site investigations show that the function of the backcalculation model is satisfactory.

Gradient MoSi2-borosilicate glass high emissivity coating with enhanced contact and impact damage resistance

High emissivity coatings on fibrous insulation tiles played an important role in thermal protection systems and thereby intrigued many researchers; however, there was little emphasis on the mechanical properties of the coatings. In this study, a gradient MoSi2-borosilicate glass coating with a dense surface layer and a porous interlayer was designed for mullite fibrous ceramics. Mechanical properties and structure parameters of the coating layers and the substrate were studied. The gradient coating was compared with a monolayer dense coating of the same composition and same surface density in contact damage resistance, impact resistance and emissivity. Compared with monolayer dense coating coated substrates, the gradient coating coated ones exhibited two times higher load bearing capacity in Hertzian indentation test at the same displacement of 1 mm; they appeared to be stiffer and harder at constant load of 20 N, and showed better impact resistance at impact energy range of 0.25–0.75 J in the falling weight test; besides, fatal radial cracks were not observed in gradient coatings after the tests. In addition, the gradient coating had higher emissivity (0.838) than the monolayer dense coating (0.816) because of the significant absorptivity increase and reflectivity decrease by small gradual slopes in the rough surface.

소형충격장비를 통한 도로상태의 진단에 관한 연구

For the faster and economical operation, this study is to propose the Light Falling Weight Test (LFWD) as the in-situ evaluation test of the pavement condition. the application case study is verified from in-situ field tests. LFWD instead of using the degree of compaction and plate bearing test is examined to pavement unbound layer condition and total pavement condition evaluation based on the in-situ elastic modulus and deflection. It is found that LFWD application is candidated from the large cylinder lab test and comparison test with dynamic plate load test. Condition analyses for the various pavement types are different using the deflections and insitu elastic modulus. Evaluation process of the pavement condition using the Light FWD Equipment is proposed and validated from case application studies.

Influence of temperature and impact velocity on the impact response of jute/UP composites

During the last decade, interest in using natural fibre reinforced composites has increased due to their good specific mechanical properties. The results of an experimental study of the influence of temperature and impact velocity on the low velocity impact response of jute fiber reinforced unsaturated polyester (UP) composite laminates is presented. A series of low velocity impact tests were performed using an instrumented falling weight test system at three different temperatures (30, 50 and 75 °C) and two impact velocities (1.5 and 2 m/s). The results indicate that jute/UP composites were able to withstand higher loads when tested at 30 °C. The composites were subsequently subjected to three-point bending tests in order to investigate the flexural strength after impact (FAI) and it was found that FAI significantly decreased with increase in test temperature. Impact damage characterised by AE revealed delamination as a major failure mode.

A Study on Impact Strength of CFRP Using Infrared Thermography

Of the advanced composite materials for aerospace structures such as aircrafts and space devices, the carbon fiber reinforced plastics (CFRP) is applied to many sectors that require lightweight materials for its high strength and stiffness. One of the disadvantages of the CFRP, however, is that it is weak against impact. In this study, impact test specimens were manufactured with five fiber stacking angles (0°/0°, 0°/15°, 0°/30°, 0°/45°, 0°/90°) according to ASTM D7136[15], and a falling weight test was performed to analyze the correlation between their mechanical and thermal characteristics. As a result, the impact energy applied to the five test specimens with different fiber stacking angles was almost constant at 30.63 J - 30.78 J. The absorbed energy increased with the increase in the fiber stacking angle, and decreased after 0°/45°. The average temperature on the fractured surface increased with the increase in the fiber stacking angle in all specimens other than the 0°/0° specimen.

Thermally activated healing in a mendable resin using a non woven EMAA fabric

This paper explores the efficacy of polyethylene- co-ethacrylic acid (EMAA), as a thermally activated thermoplastic healing agent embedded within a carbon fibre reinforced epoxy composite. EMAA fibres have been shown to effectively restore mode I properties in a fibre reinforced composite after thermal activation yet other forms of the healing agent or modes of deformation have so far not been studied at all. This work, uses EMAA in the form of a non-woven mesh, rather than a woven fabric to study the healing mechanism and effectiveness of property restoration for mode I (crack opening) and mode II (shear) failure as well as for high speed impact. Property restoration after mode I damage was found to be over 200% and increased with increasing EMAA concentration. For mode II shear failure, the property restoration was reduced to a little over 100% regardless of EMAA concentration. Mode II analysis also showed that the modulus could be restored to about 80% of its original value when modified with EMAA. Repeated impacting using a falling weight test produced no property restoration after healing, yet the modified laminates appeared protected from further damage compared with an unmodified laminate. This was attributed to the formation of a ductile thermoplastic layer mitigating further damage. Scanning electron microscopy revealed that regardless of the extent of healing, the form of the healing agent or the mode of damage, the unique pressure delivery mechanism previously identified, was always observed to occur.

Laboratory performance of crumb rubber concrete block pavement

The aim of this study was to investigate laboratory performance of crumb rubber concrete block pavement (CBP). Four different paving blocks containing 0 (control), 10, 20 and 30% rubber by total sand volume with compressive strength ranging between 23 and 64 MPa were used. The test pavement was subjected to 10,000 cycles of load repetition under a single truck wheel via a tyre inflated to 600 kPa. Nine measurements of pavement deformation and joint width were made at various stages of trafficking. Additional tests, including pull-out, skid resistances and falling weight test, were then carried out. Overall, crumb rubber CBP is observed to show inferior performance than the conventional CBP in rut, deformation, skid resistance and shear resistance but showed a great improvement in toughness. Thus, all paving blocks studied in this project have a great potential to be used according to traffic volume and types of applications.

Provision of property and cold strength uniformity with the falling weight test in coiled and sheet rolled product of steel Kh70 from a 2000 mill

A metallurgical basis is developed for providing a high set of properties of coiled rolled product, including with the falling weight test (FWT), on the basis of retaining the developed condition of austenite after controlled rolling applied to actual production conditions in a 2000 mill, including with small rolling ratios. In CherMK Severstal production has been successfully proven for coiled and sheet rolled product of steel Kh70 16 mm thick with a property guarantee with the FWT.

Study on strength of bracket plates and web plates for unseating prevention cables by falling weight test

Study on strength of bracket plates and web plates for unseating prevention cables by falling weight test

Effects of various fillers on CEM-1 laminate punchability

The primary objective of this study is to emphasize the modification of the epoxy resin formulation by implementing falling weight test to discuss reduction of impact energy and apply the thesis to improve the punchability on the CEM-1 copper clad laminate. Experimental results demonstrate that the core structure can be modified with different phenolic resin; when phenolic resin PF-440 of a smaller molecular weight is used as the modified agent, the impact energy can be lowered by 17%. In addition, three kinds of inorganic fillers, such as TiO2, Al(OH)3, SiO2, are added and the core and face structure were modified separately. Adding these fillers has a small effect on lowering the impact energy and no clear evidence of tendency, while the phenolic resin has significant effect. When 10 phr TiO2 is added to face, the impact energy can be lowered around 60% and has a visible effect on improving the punchability improvement of CEM-1 copper clad laminate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3381–3386, 2006

Study of pretreatment methods for vacuum metallization of plastics

In this study some aspects of the vacuum metallization of plastics and composite materials were investigated from an industrial point of view. The study involved the most commonly used substrate materials being ABS, PC, PP and a composite (glass fiber/epoxy resin) material. Substrates were subjected to industrially feasible pretreatments such as flame treatment, chemical treatment, mechanical treatment, oxygen plasma and also a lacquer treatment. Surface characterization before and after the pretreatments has been done by atomic force microscopy, X-ray photo-electron spectroscopy and contact angle measurements. An aluminium layer was deposited by magnetron sputtering to nominal thicknesses of 0.1 and 1.0 μm. The adhesion of the metallic layer was studied by the cross-cut test (ISO 2409) and the falling-weight test (ISO 6272), two standardized methods that can be easily performed in an industrial environment. The results indicate that these tests can only be used for a go or no-go decision on the adhesion.

A new methodology in the evaluation of non-flat plastic samples when using an instrumented falling weight test approach

The great attraction of plastics as engineering materials is the way in which their manufacture can be tailored to a specific need. A corollary of this freedom is the lack of previous test data in that precise form, and hence there is a greater necessity to evaluate the actual product's development and performance. In this respect the `instrumented falling weight' test method has proved to be of considerable value in assessing fracture toughness. However, the method has the disadvantage that the physical response of test plaques made from the same base material will probably differ markedly from that of the actual product; especially if the product has complex geometry or pronounced contours. Complex mouldings and extrusions are most likely to contain large localised residual stresses, which may be relieved or seriously modified during any process of extracting test samples. A further requirement is that there has to be a sufficiently large flat area to conduct the test and if such an area exists it is, by definition, likely to be comparatively free of residual stresses. If a `falling weight' type test is to be used, then for consistent results irregular products require the same level of physical support as the classical `flat plaque'. This paper proposes an economically viable method for conducting tests on samples of irregular profiles, while at the same time retaining the same level of rigour and consistency as conventional tests.

A study on impact properties of 3‐D composites by falling weight test method

Abstract Three‐dimensional carbon fiber/epoxy resin composites are prepared, which have either three‐axis or five‐axis fabrics (3D‐3A or 3D‐5A) in four woven gauges and four specimen thicknesses. The impact properties of these 3‐D composites are studied. The results show that when the woven gauge is decreased by 1mm, the impact perforation energies of 3D‐3A and 3D‐5A are increased by 12.6J and 5.4J, respectively, and the impact perforation energy is increased by 38J when the specimen thickness is increased by 1mm. The initial impact energy of 3D‐3A is higher than that of 3D‐5A, but the propagation energy and ductility index of 3D‐5A with a woven gauge larger than 3.75mm are higher than those of 3D‐3A. In addition, the impact properties, the impact damage area and the strength loss after impact test are better when the woven gauge is decreased.

Laboratory impact testing of rigid vinyl profiles to predict performance in punching, saw cutting, and general impact abuse

AbstractThis paper describes the results of the dropped dart impact test, the Izod impact test, and the falling weight test on several PVC profiles, extruded at various melt temperatures. Impact strength of the PVC profiles is then correlated to practical toughness of the PVC profiles, such as cutting, punching, and general abuse.

Approximative quantitative aspects of a hot spot, part II. Initiation, factors of safe handling, reliability and effects of hydrostatic pressure on initiation

The order of sensitivity in the falling weight test is calculated as a function of bubble size for a liquid explosive/bubble system. The results compare favorably with experiments, and indicate that sensitivity in such cases is not some unique property of the liquid explosive itself, but rather is a property of the liquid/bubble system. Chemically caused differences of sensitivity may be present, but are not easy to evaluate due to the poor statistical significance of go/no go experiments. Some comments on this problem are given, along with considerations of complicated initiations and the effects of hydrostatic ambient pressure on initiation. The algorithm presented previously is a guide delineating occurrences which are significant in initiation.

Shear deformation under impact conditions

AbstractThe deformation behavior that results from falling weight impact testing with flat‐headed darts is analyzed in terms of elasticity and plasticity. From a comparison of the time and temperature dependence of the yield stress that is observed during a falling weight test with the same dependences of the yield stress during simple shear tests, it is concluded that the use of flat‐headed darts results in strong shear loading. Consequently most of the plastic deformation takes place by shear flow. Of practical interest is that this leads to a simple dependence of the yield stress during the impact test and the impact energy on the plate thickness. Furthermore, for a number of cases this result allows a direct conversion of temperature effects to time effects. In practice this means that it is possible to simulate the impact behavior at very high impact rates simply by performing impact tests at lower temperatures.

レールの高周波圧接について

Recent trend in railroads in definitely toward use of long rails. In Japan also, this trend is increasingly obvious.The production of weld rails has been started for this purpose. We began to develop the technic of pressure welding by High frequency., making it possible for us to regularly produce weld rails.Follwing is characteristics of this welding process and the sammaries of results of various tests on weld rails.(1) The most important characteristics of the high frequency pressure welding method are that the reliability on the reproducibity of the joint strength is large, and that the strength is very large.(2) Necessary conditions required for successful performance of high frequency pressure weld-ing are that the upset is made after satisfactory heating.Satisfactory joints are obtained under similar welding conditions for both 50T and 50N Rails.(3) According to the results of bending tests performed with pressure welded actual rails, the strength was 112, 500-122, 000 Kg for head up and 113, 500-127, 000 Kg for head down with 50T pressure welded rails.These values are larger than the values specified by the National Railways for pressure welded rails by more than 10, 000 Kg. These values are quite satisfactory.(4) By the falling weight test performed by the step up method based upon the JIS specific-ations, the non breakage height of 50 N Rails was 2 m at the least and 3.5 m at the most, and those of 50 T Rails were 3 m at the least and 5 m at the most.These are much above the specifications given by the Notional Railways. These results are better than those of Rails, welded by different methods, namely, flush butt welded Rails, . Gas pressure welded Rails, and so on.

PROPERTIES AND USES OF SEVERAL CLAYS IN PORCELAIN ENAMELS *

AbstractThe comparative effect of several clays on the physical characteristics of typical ground‐coat and cover enamels was investigated. In the ground‐coat enamels, the effect of the clays on the firing characteristics, the development of the bubble structure, reboiling, and the set characteristics were studied. Suitable amounts of each of the clays were used as mill additions to the following cover enamels: (1) superopaque antimony frit, (2) zirconium frit, (3) a clear frit as used for colors, and (4) fluoride frit. The effect on reflectance, gloss, and the resistance to gouging was noted on these samples. Spectrophotometer curves were run on selected cover‐enamel surfaces. The clays showed a widely varying effect on the set characteristics and the bubble structure of the ground‐coat enamels. The different clays with the antimony frit caused a wide variation in the gouging characteristics while, with the zirconium frit, the clays had less effect, the gouging values being uniformly high.SummaryThe general effect of the various clays in sheet‐iron ground‐coat and cover enamels may be summarized in the following manner:(1) In the clays tested, the chemical analysis and the physical data, such as particle size, hydrogen‐ion concentration, or pyrometric cone equivalent, do not give a satisfactory basis for predicting the general usability of clays in porcelain enamels.(2) When the various clays were milled in the same ground‐coat frit and then fired, photomicrographs showed a widely varying bubble structure in the fired enamel.(3) Some of the clays brought about an earlier development of adherence or bond between the metal and the ground‐coat enamel.(4) The clays which gave a large bubble structure in the ground‐coat layer, when impacted with the falling‐weight test, gave a large fracture area, while those giving a small bubble structure caused a small fracture area.(5) The freshly milled ground‐coat enamel containing the various clays was adjusted to give (a) a pickup of 40 gm. per sq. ft., thus yielding a variable solids‐to‐liquid ratio and (b) a specific gravity of 1.65, yielding a constant solids‐to‐liquid ratio in the slips. The enamel slips were tested for the weight picked up after specific aging periods; the various clays were found to cause an increase in the weight picked up in some cases, in others a decrease, while others gave practically no change in the weight‐pickup value after various aging periods.(6) At an application weight of 60 gm. per sq. ft. the different clays caused a maximum variation of about 6% reflectance in the antimony, 12% in the zirconium, and 25% in the clear frit.(7) The spectrophotometric curves of the various clay and frit combinations showed that the clays gave uniform spectral values in the antimony and clear frits; in the zirconium frit, a greater variation in reflectance was found in the red portion of the spectrum than in the blue or green portions.(8) The various clays in the antimony frit showed a marked difference in the gouging characteristics of the surfaces, while in the zirconium frit the clays caused only a slight variation in gouging as all of the values were uniformly high.