International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2015): 6.391 Volume 5 Issue 5, May 2016 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Tactile Perception of Passenger Vehicle Interior Polymer Surfaces: An Investigation using Fingertip Blind Observations and Friction Properties Mohammad S. Alsoufi Mechanical Engineering Department, Collage of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah, KSA, Abstract: There is a growing demand for “soft-touch” materials for use in, for instance, interior components of cars, and similar goods that are subject to hand-held contact. The current study focused on touch-feel perception (human fingertip - blind observer) and friction properties in an air-conditioned room, with an ambient temperature of 20±1 o C and a relative humidity of greater than 40±5% RH. The conclusion leads to within the sight observers, 60% contributed with regard to the tactile sensory input, and 40% contributed with regard to the visual sensory input. Therefore, both attributes contributed to the final decision, with a 99.7% (±3σ) level of confidence. On the other hand, within the blind observers, 60% contributed with regard to the tactile sensory input, and 0.0% contributed with regard to the visual sensory input, with a 60% (±1σ) level of confidence. Moreover, there is a strong correlation between the pattern for both genders (blind observers) to prefer S1 material as the smoothest one. Also, there is a strong correlation between the pattern for both genders (sight observers) to prefer S5 for both and S9 for women as the smoothest material and the preferred one. Furthermore, there is a strong correlation between sight (Women) observers and surface roughness, R a . On the other hand, there is no correlation between blind (Women, Men) observers and surface roughness, R a , results. Keywords: Perception; Fingertip; Surface Roughness; Polymer; Friction Properties. 1. Introduction There is a great deal more to a product’s functionality than purely technical engineering features. As the engineering quality of various products is no longer a distinctive selling point but rather a minimum requirement, consumers are seeking emotionally interesting goods. Moreover, well- designed, attractive sensory products generate a strong customer-product relationship, which can most definitely extend a product’s lifetime decisively as an early replacement is prevented, thus reducing energy and material consumption, a core factor in eco-design and sustainability strategies [1]- [3]. Materials selection is a mature discipline where physical parameters such as surface roughness, elastic friction modulus, shear strength and many others are used to predictors of how a material will perform in technical applications [4]. Over the years, studies of psychophysical research have been carried out in the field of vision, gustatory and auditory perception. However, only little has been conducted with regard to the tactile, missing the opportunity to work on the second vital sense after vision, when it comes to product perception and probably the dominating one during the production stage [5]. Particularly, in cars, customers spend the majority of their contact time inside the cars, the choice of materials used in the interior can have a considerable impact on the customer’s decision/behavior and sensory engagement. This has led to so-called effective engineering, the study of “human-product” interaction at a “soft-touch” subject level, which was pioneered as Kasei Engineering in Japan [3]. 1.1. Process of Perception (Touch and Vision) Humans are extremely adept at recognizing common objects by touch-vision [6]. The process of tactile perception is structured into three levels: (1) biophysical interaction level, (2) neuron sensory level and (3) perception evaluation level [2]. Figure 1 shows the process of the touch-feel perception (e.g., finger touch). Figure 1: The process of tactile perception, adapted from [2] 1.1.1. Biophysical Interaction Level As humans touch surfaces with their fingers, their complicated motions lead to the physical interfacial interaction between the epidermis skin layer (about 0.1 – 0.2 mm in depth) and a surface. Not only the surface properties such as texture and strength affect this interaction, but also the variation of skin conditions due to a series of physiological mechanisms related to the skin, e.g., blood circulation, sebum/sweat lubrication. Physically, the interfacial could lead to changes of strain/stress or thermal state at the dermis layer. Paper ID: NOV163747 1447