Proposal of the Measurement Conditions for Hanji–Determination Folding Endurance

This study aims to optimize the measurement conditions of handmade Hanji paper to reduce the time required for measurement while meeting folding endurance standards, for various basis weights. Thirteen types were selected, including 12 types of Hanji with grammages of 17 g/m2, 30 g/m2, and 45 g/m2, and one type of 75 g/m2 copy paper, and 24 sheets were prepared in the laid and chain directions. Subsequently, folding endurance experiments at different load (14.72 N, 9.81 N, 4.91 N) and specimen width conditions (15 mm, 10 mm, 5 mm) were performed, using a 4-MIT folding endurance tester. The results showed that, for specimen widths of 15 mm and 10 mm under a load of 4.91 N, the folding endurance falls within the reference range (10∼10000 times). In particular, reduced folding endurance range and measurement time were observed at a width of 10 mm under a load of 4.91 N. Moreover, the endurance trend lines based on the average values of load and specimen width ranges enabled the prediction of the folding endurance within those ranges, according to the decreasing slope. Furthermore, for a specimen width of 15 mm under a load of 4.91 N, the folding endurance in the comparison group (35 to 17723 times) significantly exceeds the upper limit of the reference range (10∼10000 times). Therefore, the measurement conditions of 4.91 N with a specimen width of 10 mm are proposed.

Aspects of Selecting Appropriate Conveyor Belt Strength

Breaks in the so-called “continuous” (unspliced) belt sections, and not in the spliced areas, are infrequent but do happen in practice. This article presents some aspects, which may account for such breaks in conveyor belts. It indicates the so-called “sensitive points” in design, especially in the transition section of the conveyor belt and in identifying the actual strength of the belt. The presented results include the influence of the width of a belt specimen on the identified belt tensile strength. An increase in the specimen width entails a decrease in the belt strength. The research involved develops a universal theoretical model of the belt on a transition section of a troughed conveyor in which, in the case of steel-cord belts, the belt is composed of cords and layers of rubber, and in the case of a textile belt, of narrow strips. The article also describes geometrical forces in the transition section of the belt and an illustrative analysis of loads acting on the belt. Attention was also devoted to the influence of the belt type on the non-uniform character of loads in the transition section of the conveyor. A replacement of a conveyor belt with a belt having different elastic properties may increase the non-uniformity of belt loads in the transition section of the conveyor, even by 100%.

Effect of Superficial Scratch Damage on Tension Properties of Carbon/Epoxy Plain Weave Laminates

The effect of scratch damage on the tension properties of carbon fiber plain weave laminates has been studied in detail using digital image correlation (DIC) and acoustic emission (AE). A range of scratch lengths was machined onto different laminates. The bearing capacity of the laminates was then compared with that of unaltered samples. The strain field distributions near the scratches were measured and analyzed as a function of scratch length with DIC. Initiation and propagation of damage were monitored during the tensile tests using AE. Failure sites and morphologies were observed and analyzed. The results show that superficial scratches have little effect on the strength of plain weave laminates when the scratch length is less than 80% of the specimen width. Scratches affect the distribution of strain near the scratch but not far away from the scratch or at the back face of the sample. Not all samples broke from the scratch site but instead broke from the free edge of the sample or close to the gripping region.

Size Effect on the Bond Behavior of Grouted Reinforcing Bars Embedded in Light-weight Concrete

This study presents experimentally the bond behavior of light-weight concrete specimens with grouted reinforcing bars in comparison with conventional concrete specimens. A total of (9) pull-out specimens were studied; (3) specimens of conventional concrete, (3) specimens of light-weight concrete, and other (3) specimens of grouted light-weight concrete. Two variables are adopted in this investigation: specimen width and type of concrete (conventional concrete, light-weight concrete and grouted light-weight concrete). The study contains a discussion of the general behavior of the specimens in addition to the study of the ultimate bond capacity, maximum bond stresses and the relationship between the stress and the slip for different pull-out specimens. Results show that bond strength is highest for the largest specimen size (bond strength of grouted light-weight concrete specimen with specimen width 400 mm is higher than that of the specimen with (200 mm) width by about (13.13%)). Also, bond strength is highest for the grouted light-weight concrete specimen (bond strength of grouted light-weight concrete specimen is higher than conventional concrete specimen by (11.11%)).

Determination of the Shear Strength of Rockfill from Small-Scale Laboratory Shear Tests: A Critical Review

Determining the shear strength of rockfill is a key task for the design and stability analysis of rockfill structures. When direct shear tests are performed, the well-established ASTM standard requires that specimen width and thickness must be at least 10 and 6 times the maximum particle size (dmax), respectively. When the value of dmax is very large, performing such tests in laboratory with field rockfill becomes difficult or impossible. Four scaling-down techniques were proposed in the past to obtain a modeled sample excluding oversize particles: scalping, parallel, replacement, and quadratic. It remains unclear which of the four scaling-down techniques yields reliable shear strength of field rockfill. In this paper, an extensive review is presented on existing experimental results to analyze the capacity of each scaling-down technique to determine the field rockfill shear strength. The analyses show that previous researches followed an inappropriate methodology to validate or invalidate a scaling-down technique through a direct comparison between the shear strengths of modeled and field samples. None of the four scaling-down techniques was shown to be able or unable to predict the field rockfill shear strength by extrapolation. The analyses further show that the minimum ratios of specimen size to dmax dictated by well-established standards are largely used but are too small to eliminate the specimen size effect. In most cases, this practice results in shear strength overestimation. The validity or invalidity of scaling-down techniques based on experimental results obtained by using the minimum ratios is uncertain. Recommendations are given for future studies.

Failure of En19 Taper Thread Tool On Welding Ms Plate

FSSW is used a lot of vicinity which are from marine to aerospace industry. FSSW is effected with tool rotational speed, tool transverse speed, dwell time and tool plunge depth. One of them is weight. With the reference to the research work In this paper two flat plates of similar metals of MS of 1.2 mm thickness & 30.25mm specimen width are subjected to a solid state welding at 900rpm using the EN19 taper thread tool. The tensile-shear test results showed that the FSSW specimens are better than the specimens welded by the conventional FSSW process at 900-1300 tool rotational speeds with using taper thread tool pin profiles. By doing tensile test following ASTM B 557:2006 procedure the ultimate shear load obtained from the conventional friction stir spot welds is 1.960KN.

Application of computed tomography to hole expansion measurements

Purpose The purpose of this paper is to investigate a possibility of determination of the rivet hole expansion with the use of computed tomography (CT). This method offers several benefits in comparison to the traditionally used destructive methods. Design/methodology/approach The measurements of rivet hole expansion were performed on three specimens with the use of CT. Then, the same specimens were measured with the use of the conventional destructive method. This allows to estimate accuracy of the proposed method and characterize its advantages and limitations. Findings Good correlation with the destructive method has been obtained. The proposed method enables more detailed analysis of a joint as arbitrarily oriented cross-section for analysed area can be easily generated and increase of measurements number is always possible and simple. The disadvantage of the method is lower accuracy of diameter determination than in the case of conventional methods. Research limitations/implications The measurements were performed only on one type of specimens. Probably, if a rivet and sheets were made of the same alloy, the measurements would be barely possible. The rivets were installed with squeezing ratio D/Do = 1.7 whose value is close to maximum as defined in riveting instructions (Kaniowski, 2015). This means that measured hole expansions were higher than in typical joint. The proposed method is appropriate for simple specimens (one rivet at a specimen width). Practical implications The investigation shows that rivet hole expansion can be measured with the use of CT. This method is useful especially when destruction of a specimen is not allowed or more detailed analysis is required (e.g. measurements on many depth levels). Originality/value The paper presents measurements of rivet hole expansion with the method which has not been used before for this application. Advantages and limitations of the proposed approach compared to conventional methods are discussed.

Investigation of tear strength of an airship envelope fabric by theoretical method and uniaxial tear test

This article proposed a new convenient method to obtain tear strength of an airship envelope fabric, which is a laminated plain weave fabric with the ultra-high molecular weight polyethylene fibers. First, a modified formula based on Maekawa’s empirical formula was derived. Uniaxial tear tests were then conducted on three series of single-edge notched specimens with varying widths and their critical tear stresses were measured. The experimental result showed that critical tear stress decreases with the reduction of specimen width when initial crack length is fixed. Afterward, the tear stresses of the fabric were simulated by Maekawa’s empirical formula, the modified formula, and Thiele formula. By comparing the theoretical results with the experimental results, the modified formula was verified to be consistent well with the test data. Finally, an equation was derived, which shows tear strength of this fabric decreases as initial crack length increases. For instance, when the initial crack length is 31.75 mm, the tear strength is only 44.52% of the tensile strength.