b. i. In your own words, give a brief description of what the standard covers. Standard is a measure of assurance to any specific area of application. It covers a number of elements such as uniformity, specialization, purpose, precision and accuracy. Uniformity of standard is a frame of reference that the users of a given object can agree to follow regarding the manufacturing and usage of that particular design as well as the object material (Callister, 2004, p. 503). Uniformity regards the conformity of products regarding their physical and chemical nature. Specialization involves the product being designed for a specific project such that outside the same parameters, it’s an inadequate design. Purpose in standardization is the objective that is associated with a given outcome. Purpose may be safety, protection, repairs, constructions and more. Precision and accuracy in standardization are concerns of the physical fitting associated with an outcome. The simplest measure of accuracy and standardization lies in the sizes of the products. Size determines the fitting of the object. ii. Give a brief description, from the sections of the standard, of five basic design requirements for the helmet. Uniformity: the design of the helmet has to be specific to the initial design solution, for a particular product such that all the helmets of a design are similar and as close as possible to the suggested solution. Specialization: helmets in use are designed for various purposes, the cycling and the
industrial helmets are quite different and they are specific to their function. In this case specialization means that the design of the helmet meets the needs of a given industry as noted above. Purpose: the helmet is basically a protective equipment, but different scenarios have different dangers and risk. The purpose of the helmet is to protect the head from injuries, but it is specific to the type of injuries. Precision: precision of the helmet involves the testing capacities. The device is supposed to withhold a given force of a certain nature. In considering the forces involved, the helmet is designed for a certain force under which it serves its purpose. Accuracy: accuracy of the helmet provides a range in which the helmet maintains and performs its functionalities (Voland, 2003, p. 298). Accuracy falls within the testing range as well, but provides an average under which the helmet is to serve its purpose. c. BS EN 1078 specifies the following for the testing of the helmet: • a dummy head of mass 6.1 kg in a test helmet is dropped onto a stationary anvil • two impact speeds are used of 5.42ms-1 and 4.7ms-1 • the test requires that the deceleration experienced by the dummy head does not exceed 250 x g where g is the acceleration due to gravity. i. Show that the heights from which the helmet and dummy head should be dropped in the tests are equivalent to those stated in the note to section 4.4 of the standard. Show your working, and state any assumptions that you make. Assumption: the dummy freefalls from the initial position, where V0 = 0 ms-1 V2 = 2 aS, where a is the acceleration due to gravity g which is approximated at 9.8 ms-1 i. (5.42)2 = 2(9.8)S S = 29.3764/(19.6) = 1.498795918 m = 1.5 m ii. (4.7)2 = 2(9.8)S S = 22.09/(19.6)1.127040816m = 1.1 m ii.