LOWER TOLERANCE LIMIT APPROACH TO EQUATION-BASED RATIONAL DESIGN VALUES FOR T-SHAPED MORTISE AND TENON JOINTS

A nonlinear regression expression was fitted to the test data obtained from a study of the bending moment capacity of 320 rectangular T-shaped mortise and tenon furniture joints consisting of 64 configurations of five specimens each. A statistical lower tolerance limit approach was then used to explore the degree to which these values should be reduced when used for design purposes and the confidence that a user might have in these reductions. The procedure followed was to apply statistical lower tolerance limit techniques to the ratios obtained by dividing each test value by its corresponding estimated value. To gain insight into the relationship of a specific confidence–proportion level and its corresponding reduction factor on the percentage of an estimated value that could be used for design purposes, lower tolerance limits were computed for four confidence–proportion levels. The results illustrate a statistical technique that can be used to determine reduction factors and the impact of the selection of any of the given confidence–proportion levels on design values.

EFfect of Adhesive Type and Tenon Size on Bending Moment Capacity and Rigidity of T-Shaped Furniture Joints Constructed of Turkish Beech and Scots Pine

Tests were carried out to determine the effect of wood species, adhesive type, and tenon width and length on static bending moment capacity and rigidity of T-shaped mortise and tenon furniture joints. For this purpose, 320 round-edged mortise and tenon joint specimens were constructed—half of Scots pine (Pinus sylvestris L.) and half of Turkish beech (Fagus orieantalis L.)—and subjected to static bending loads. Tenons varied 30-60 mm wide and 20-45 mm long. Joint specimens were assembled with 65% solid polyvinyl acetate and polyurethane adhesives. Results of the tests indicated that the joints became stronger and stiffer as either tenon width or tenon length increased. Results also indicated that tenon length had a more significant effect on moment capacity of joints than tenon width, whereas tenon width had a more significant effect on joint rigidity than tenon length. Bending moment capacity of the joints ranged from a low of 125 Nm for joints with tenons 30 mm wide x 20 mm long to a maximum of 393 Nm for joints with tenons 60 mm wide x 45 mm long. Rigidity of the joints ranged from a low of 2278 Nm/rad for joints with tenons 30 mm wide x 20 mm long to a maximum of 5733 Nm/rad for joints with tenons 60 mm wide x 40 mm long. An empirically derived expression was developed to predict average ultimate bending moment capacity

“There Are No Known Benefits...”: Considering the Risk/Benefit Ratio of Qualitative Research

Institutional review boards (IRBs) are responsible for weighing the risks and benefits of research participation. Qualitative researchers note numerous instances where IRB ethical frameworks fail to align with the ethics of their research projects and point out that IRB understandings of the benefits and risks of research often differ from those of the participants they seek to protect. This qualitative cross-case research investigates participants’ interview experiences in six qualitative studies that differed in their methods, subject of focus, and populations. Our findings indicate that contemporary IRBs’ use of population “vulnerability” and topic “sensitivity” to assess project risk does not adequately determine the benefits, risks, or ethicality of research. We recommend that IRBs treat as real the evidence for benefits in qualitative research, recognize that sensitivity and vulnerability do not predict risk, and encourage researchers to attend to relationships in their projects