ABSTRACT
Riveting is the most important method of joining sheet metal and is widely used in the assembly of aircraft components. The perpendicularity error of the holes is unavoidable during automatic drilling and riveting, which has a significant impact on the quality of the assembly. In this paper, the effects of hole perpendicularity error and squeeze force on the interference fit size, interface contact state, microstructure morphology, fatigue life, and fracture form of riveted joints were investigated experimentally. The results show that the interference fit size increases with a greater tilt angle. When the tilt angle is 0°, the rivet shank is in close contact with the inner and outer sheets, and there is no obvious gap at the interface between the rivet and the sheets. As the tilt angle increases to 2° and 4°, a gap appears at the interface of regions 1, 2, and 3, while the rivet shank at region 4 is in close contact with the outer sheet. The fatigue life decreases when the tilt angle increases from 0° to 4°. For the same tilt angle, the fatigue life of riveted joints with a 0° tilt direction is higher than that of riveted joints with a 180° tilt direction. Increasing the squeeze force can to some extent reduce the adverse effect of the tilt angle on the fatigue life. The hole perpendicularity error does not affect the failure form, while the squeeze force has a significant effect on the failure form of the specimens. RESEARCH HIGHLIGHTS: The fatigue life of riveted joints decreases as the tilt angle increases. The size of the interfacial gap increases with increasing tilt angle. Higher fatigue life at 0° tilt direction than at 180° tilt direction. Increasing the squeeze force can somewhat reduce the negative effect of tilt angle on fatigue life.
ABSTRACT
In the automatic drilling and riveting process, the perpendicular error of the hole is inevitable, which has a great influence on the assembly quality. In the current research, the shear and pull-out behaviors of riveted joints under different perpendicularity errors and squeeze forces were investigated and compared by the quasi-static tests. The fracture of the failed samples was characterized by a scanning electron microscope and the formation process of fracture was discussed. The failure mechanisms of riveted joints were analyzed in detail to guide engineering applications. The test results demonstrated that the shear load and pull-out load of riveted joints increased slightly with the increase of the tilt angle from 0° to 4°. The perpendicularity error did not affect the shear and pull-out failure modes of the riveted joints. However, the squeeze force had a significant effect on the failure modes of the pull-out samples. Fracture analysis showed that the failure of all shear samples occurred at the rivet shaft. Besides, when the squeeze force increased from 15 kN to 23 kN, the failure modes of the pull-out samples changed from the sheet to the rivet itself.
ABSTRACT
Objective: Glaucoma is the most frequent cause of blindness in Japan and is primarily treated using IOP-lowering ophthalmic solutions. Although the patients themselves frequently instill ophthalmic solutions, instillation by caregivers may be necessary for various reasons. Therefore, we evaluated pharmaceutical characteristics of antiglaucoma ophthalmic solutions and their usability from the caregivers' viewpoint.Methods: Five dorzolamide hydrochloride-timolol maleate ophthalmic solutions and 2 travoprost-timolol maleate ophthalmic solutions were evaluated concerning the pharmaceutical characteristics and subjective squeezability rated by adults aged 20 years or above.Results: Among the dorzolamide hydrochloride-timolol maleate compounding ophthalmic solutions, the squeeze force was the lowest in COSOPT® ophthalmic solution (11.8 N), and DORMOLOL® combination ophthalmic solution NITTEN was rated highest, with 68.2% of the subjects placing it within the top 3 levels of a 7-level scale. Of the travoprost-timolol maleate ophthalmic solutions, the squeeze force was 9.8 N, lower than the pioneer drug, in TraTimo® combination ophthalmic solution NITTO, which was also rated in the top 3 levels by 90.3% of the subjects. A strong negative correlation was observed between the squeeze force and squeezability.Conclusion: In instillation by caregivers, the squeeze force was shown to be correlated with subjective squeezability as in instillation by patients themselves. This study provided information concerning the usability of ophthalmic solutions from the caregivers' viewpoint. For the future, it is necessary to select ophthalmic solutions from the caregivers' as well as the patients' viewpoints by utilizing information obtained in this study.
ABSTRACT
<b>Objective: </b>The squeezing force and one-drop weight, suggested to directly influence adherence, were measured in 6 eye drop products containing a switch OTC drug, ketotifen fumarate, to investigate useful information for product selection.<br><b>Methods: </b>The squeeze force, one drop weight, and pH were measured using a digital force gauge, analytical balance, and pH meter, respectively. Information on additives contained in each product was collected from package inserts. For the total number of drops, the number per 10 mL was calculated from the obtained value.<br><b>Results: </b>The maximum squeeze force was 14.8 N of Irice AG Guard, and the one drop weight (33.2 mg) of Raferusa®AL was the minimum. The total number of drops per 10 mL was 215 in Sutto eyes Z, being the minimum. The pH was in the range of 5.2-5.7. On comparison of additives among the products, a cooling agent was contained in only 2 products.<br><b>Discussion: </b>Since the squeeze force was in the range of 5.3-14.8 N, it was less likely that the squeeze force reduces usability. Since the one-drop weights of 2 products were more than 10 mg lower than the weights of the other products, the dose may be insufficient and the effect may not be attained. The pH was within the acceptable range in all products. Two products contain a cooling agent as an additive, and this has to be explained beforehand. Information related to usability, actual feeling of the effect, and sense of the use of the products containing ketotifen fumarate was collected.
