mechanical comfort
DESCRIPTION
A brief description of mechanical comfort. It covers types and measuring methods. Discussion is also about subjective and objective assessment.TRANSCRIPT
Mechanical comfort: One of fundamental need of human body Dr Muhammad Mushtaq Mangat
www.mushtaqmangat.org http://www.healthyheating.com/Thermal_Comfort_Working_Copy/HH_physiology_4_nerves.htm
Mechanical comfort is
also known as:
Skin sensational wear comfort
Tactile comfort Sensorial comfort Movement
comfort Dynamic comfort
Mechanical comfort Mechanical comfort is
deeply rooted in feeling of a person due to any interaction between clothing and skin
Judged by subjective evaluation
Is based on: Skin sensation
Touch by human body parts
Context in which fabric is touched
Response profile of person
Pressure
Friction
Diverse aspects of mechanical comfort
Assessment of user keeping in mind place, seasons, fashions and personal preferences [6]
Stimulation developed by friction between hand and fabric [7]
Personal feeling after taking fabric in hand [7]
Comprehensive observation based on sensation when a textile fabric is taken into control with the help of hand, fingers and rolled around[7]
Responses of nerves based on thermal, pressure, pain [8]
Types of Mechanical Comfort
Tactile sensations: prickly, tickling, rough, smooth, craggy, scratchy,
itchy, picky, sticky.
• Moisture sensations: clammy, damp, wet, sticky, sultry, non-absorbent,
clingy.
• Pressure (body fit) sensations: snug, loose, lightweight, heavy, soft, stiff.
• Thermal sensations: cold, chill, cool, warm, hot [7,8]
Psychophysical comfort
It ideals with quantitative investigation of interaction between stimulus and sensation of human body
It is a type of study, which measures the sensation perceived by human due to any stimulus acts on human skin
It depends upon subjective feelings of persons
Action is purely mechanical and impact is assessed on the basis of subjective feelings
Factors affecting psychological comfort [2, 5]
Bending rigidity
Drape of fabric
Shear resistance
Elasticity and elastic recovery
Surface roughness
Friction of coefficient
Surface smoothness
Tensile strength
Porosity of fabric
Composition
Thickness
Density
Type and fineness of fibers
Alignment of fibers in yarn and yarn thickness
Dimensional rigidity and friction
Match between human body size and clothing size
Surface profile variation
Compressibility of fabric
Skin and sensation
Human skin is quite sensitive to any change occurring in the environment
Finger tip has more than 300 receptors
One of the functions of skin is to intimate any change in any part of the body through human body signal system to brain for necessary actions
Generation of signals depends upon the contact between clothing and skin
It is a complex sum of a number of receptors reporting feeling of texture, stress, dimensional change, change in temperature, deformation ,vibration etc.
Subjective assessment depends
Depends upon
Assessment conditions
Assessment technique
The method of ranking
Scaling the assessment
Analysis of the results [12]
Influential factors
Gender, age, education and cultural backgrounds are potential. Female are more sensitive than man [13]
Four handle methods [11]
Types of sensations
Touch pressure (mechanoreceptors)
Cold (thermo receptors)
Warm (thermo receptors)
Pain
Itch
[McGraw-Hill Concise Encyclopedia of Bioscience]
There are five basic qualities of sensations occur in the sensory nerves of skin.
Cutaneous sensation A specific set of nerves for each type of sensations
Finally, a comprehensive sensation emerges from the integration of these sensations
At each spot, there is one kind of nerve
There is no overlapping
Each nerve does a specific job and sends signals
Finally, at one point in brain all signals are processed and comprehensive observation is developed… all such sensation is called Cutaneous sensation
Types of mechanoreceptors
There are seven kinds of mechanoreceptors present in the skin
Receptor Type Sensation Meissner Corpuscle Stroking, fluttering Pacinian Corpuscle Vibration Merkel Disc Pressure, texture Ruffini Ending Skin stretch Hair tylotrich, Hair guard Stroking, fluttering Hair-down Light stroking
Seven Types of mechanoreceptors [1]
Some retain their position for longer time and other may come back quickly
Somatic sensation
Sensory information collected through nerve system is called somatic senses
Three categories: Mechanoreceptors – stimulated by
mechanical displacement
Body Thermo receptors –temperature changes Nocio receptors –pain sense
Human Skin published by WebMD LLC 2009
Skin response
Skin experiences two types of sensations:
1. There is a pressure, friction or and constriction on the
2. Change in temperature and moisture on the surface of the skin
Share % of different feelings
Final decision of customer depends upon: smoothness (28%)
softness (22%) stiffness (8%)
roughness (7%) thickness (5%) weight (5%)
warmth, hardness, elasticity, creasing propensity, drape etc. (25%) [7,9]
Fabric deformation [10]
Sensation process Touching of fabric with fingers
Complex multi-sensory, emotional and cognitive experience starts
Memory is stirred
Emotion, feeling and association takes place
Minds decides based on experience and memory,
Impression is embossed in the mind
Decisions and motivations are linked with anticipated reality of preference, personality ,emotion and moods [11]
Engineering approach and clothing
Following factors should be considered during designing of clothing: Placement (where on the body it should
go) Form Language (defining the shape) Human Movement (consider the dynamic
structure) Proxemics (human perception of space) Sizing (for body size diversity) Attachment (fixing forms to the body) [3]
Thermal sensation of skin and regional diversification
Different parts of body have different sensation of hot and
cold. Three parts of the body; face, under arm and legs have different sensation
Face is much sensitive to hot as compared to leg, no big difference is in case of cold. No big difference in skin sensation during winter times in different parts of body
In winter; face may be exposed to environment. Nevertheless, people cover their faces if they experience strong wind. [4]
People in deserts cover fully their faces to prevent any loss to skin from heat. Veil by Muslim women is another example to understand the significance of face protection during summer.
Man in desert Face is fully covered
Subjective assessment of fabric
It is a psychological reaction due to touching and intimated to brain through nerves
Individuals are used as a tool to estimate the properties of fabric
When a person runs their finger across the surface of a fabric, a complex multi-sensory,
emotional and cognitive experience takes place. A memory is stirred, an emotion, feeling
and association is evoked and a decision is made, an impression becomes embossed in the
mind. Decisions and motivations are based on anticipated reality of preference, personality,
emotion and moods, for audience or non-audience participation (Moody et al., 2001).
Objective measurement systems
Objective measurement is a method which instrumental measurement is carried out and final assessment is made regarding the mechanical comfort of fabric
The KES-F system (Kawabata’s Hand Evaluation System for Fabrics) in 1972 is an example which is much in use and reliable [14]
The Kawabata Evaluation System for Fabric (KES-F) which has been widely used since the
KES consist of four sets: FB1 for tensile and shearing FB2 for bending FB3 for compression FB4 for surface friction and variation
A total of 16 parameters are measured
KES Measuring system [14]
KES measuring system[13]
FAST (Fabric Assurance by Simple Testing)
Developed by The Australian CSIRO
Alternative of KES, relatively inexpensive, reliable, accurate, robust and simple to operate
FAST System detail [15]
Individual objective measurement testers [16]
Stiffness tester and circular bending rigidity tester by Shirley
Drape meter sharp corner drape meter for drape properties by Cusick
Tensile testers for tensile and shear properties, thickness gauges for thickness and compression properties,
Universal surface tester and Frictorq for friction properties by Universalcan
Griff-Tester for fabric extraction method and devices
Stiffness and bending tester [17]
(a) Image analysis system, (b) Captured image on the drape meter [10] (c) Sharp corner tester [2]
The relationship between the subjective and objective evaluation
Subjective is based purely on personal assessment
Lot of conflict between subjective and objective evaluation
Many ways have been developed to decrease the distance between subjective and objective evaluation
Following are few methods commonly used:
Steven`s law, Rank correlation, linear regression mode, Multiplefactor analysis, weighted euclidean distance, Component analysis, Decision and information theory, Canonical correlation methods, fuzzy logic–based methods, neural network statistical models … many more
References [1] Dunne, L.E. Psychophysical Elements of Wearability. . in CHI 2007
2007. San Jose, CA, USA.
[2] Hes, L. Fundaments of design of fabrics and garments with demanded thermophysiological comfort. in International Round Table «Clothing Comfort – Condition of Life Quality» 2009. Romania
[3] Goldman, R.F., Thermal Factor: Concepts and Definitions, in Clothing Comfort Intercation of Thermal, Ventilation, Construction and Assessment Factor, N.R.S. Hollies, and Goldman, R. F., Editor 1977, Ann Arbor Publishers: Michigan. p. 3-8.
[4] Elansaria, A.M., and Hobanib, A.I., , Effect of Temperature and Moisture Content on Thermal Conductivity of Four Types of Meat. . International Journal of Food Properties, 2009. 12(2): p. 308 - 315.
[5] Ancutienė, K., and Sinkevičiūtė, D., The Influence of Textile Materials Mechanical Properties upon Virtual Garment Fit. MATERIALS SCIENCE (MEDŽIAGOTYRA), 2011. 17(2): p. 160-167.
[6] Bakar, B.A. (2004). Subjective and Objective Evaluation of Fabric Handle Characteristics, The University of Leeds, Department of Textile Industries, Master of Science
[7] Bishop, D. P. (1996). Fabric: Sensory and Mechanical Properties, The Textile Institute, Textile Progress, UK, Volume 6, No:3, ISBN 1 870812751
[8]Dhinakaran M., Sundaresan S. & Dasaradan B.S. (2007). Comfort Properties of Apparels, The Indian Textile Journal, Vol.32, pp. 2-10
[9] Grinevičiūtė, D., Daukantıenė, V., Gutauskas, M. (2005). Textile Hand: Comparison of Two Evaluation Methods, Materıals Scıence (Medžıagotyra), Vol. 11, No. 1. 2005, pp. 57-63 ISSN 1392–1320
[10]Hu, J. (2004). Structure and Mechanics of Woven Fabrics, CRC Press Boca Raton Boston New York Washington, DC, Woodhead Publishing Limited Cambridge England
[11] Moody, W., Morgan, R., Dillon, P., Baber, C., & Wing, A. (2001). Factors Underlying Fabric Perception. In: 1st Eurohaptics Conference Proceedings. Birmingham
[12]Mahar, T. J., Wheelwright, P., Dhingra, R. C. & Postle, R. (1990). Measuring and Interpreting Fabric Low Stress Mechanical and Surface Properties, Part V: Fabric Hand Attributes and Quality Descriptors, Textile Research Journal, 60, pp. 7-17.
[13] Mäkinen, M., Meinander, H., Luible, C., Magnenat-Thalmann, N. (2005). Influence of Physical Parameters on Fabric Hand, Proceedings of the HAPTEX'05 Workshopon Haptic and Tactile Perception of Deformable Objects, Hanover, December
[14] Gonca Öz.elik Kayseri, Nilgün Özdil; Gamze Süpüren Mengu , Sensorial Comfort of Textile Materials. www.intechopen.com, 2012
[15] Saville, B. P. (1999). Physical Testing of Textiles, Woodhead Publishing Ltd, Cambridge England, ISBN 0849305683
[16] Kim, J.O., Slaten B.L. (1999). Objective Evaluation of Fabric Hand Part I: Relationships of Fabric Hand by the Extraction Method and Related Physical and Surface Properties, Textile Research Journal, Vol.69 (1), pp. 59-67
[17] Silva, L.F., Seabra, E., Lima, M., Vasconcelos, R., Alves, J., Guise, C., Martins, D. (2010). A Successful Partnership for the Development of a Laboratory Friction Testing Apparatus: A Project Review, International Conference on Engineering Education Proceedings, July 18–22, Gliwice, Poland