Manufactured part based on the drawing must be inspected for quality control. If no restraint note is specified on the drawing, the part should be inspected without any clamping(restraining). However if there is a restraint note, the part is non-rigid part. When inspecting non-rigid parts, there are two areas that need special attention: proper restraining of the part and determining which tolerances are checked in the retrained state. Mounting and restraining the part on the appropriate datum features is the first area. When retraining the part, the only forces that should be used are the ones described in the restraint note. The sequence for applying the restraining force specified on the drawing should be followed. The location, direction and amount of force should be in accordance with the restraint note. Once the part is restrained, the tolerances can be verified. When inspecting non-rigid part, the inspector needs to determine which dimensions and tolerances are to be checked in the retrained state. Careful reading of the restraint note will indicate if all or certain tolerances are to be checked in the restrained condition. Each feature control frame should be examined for the use of free state modifier. If a free state modifier is specified, the geometric control should be inspected with the part in the free state. When inspecting a non-rigid part on a coordinate measuring machine(CMM), fixture and clamp should be used to locate and clamp the part. The fixture will establish the proper part restraint conditions and datums. If a fixture is not used when inspecting non-rigid parts, it will be difficult or impossible repeatable measurements.
Defining and measuring non-rigid or flexible parts has been controversial in industry for many years. There are two primary areas of controversy. The first is agreeing on what exactly a non-rigid part is. The second is agreeing on how to define and measure a non-rigid part. The subject of non-rigid parts is further complicated by the brief coverage it receives in the national and international standards. This leaves each company to improvise or create its own rules for non-rigid parts. There are some who believe that Geometrical Dimensioning and Tolerancing (GD&T) should not be used on non-rigid parts. This is not true. The ASME Y14.5M standard applies to rigid parts as a default condition. However, there is no definition given for a rigid part. The term rigid part has been used in industry for so long that it has gained a definition by its general use. When most people in industry say rigid part, they are referring to a part doesn’t move (deform or flex) when a force (including gravity) is applied. How much force is relative based on the part characteristics. In reality, all parts will deform (or flex) if enough force is applied. Using this logic, all parts would be considered non-rigid. However, we all know that this is not how parts are treated in industry. Although GD&T defaults to rigid parts, it should also be used on non-rigid parts with a few special techniques. Actually 50~60% of all products designed contain parts or features on parts that are non-rigid. Therefore, we try to suggest the definitions of rigid and non-rigid parts and method to measure non-rigid parts.
One of the most performed action in daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over 25°, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than 25° for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on 0° to 25° tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.