mechanical comfort

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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

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A brief description of mechanical comfort. It covers types and measuring methods. Discussion is also about subjective and objective assessment.

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Page 1: Mechanical Comfort

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

Page 2: Mechanical Comfort

Mechanical comfort is

also known as:

  Skin sensational wear comfort

  Tactile comfort   Sensorial comfort   Movement

comfort   Dynamic comfort

Page 3: Mechanical 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

Page 4: Mechanical Comfort

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]

Page 5: Mechanical Comfort

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]

Page 6: Mechanical Comfort

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

Page 7: Mechanical Comfort

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

Page 8: Mechanical Comfort

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.

Page 9: Mechanical Comfort

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]

Page 10: Mechanical Comfort

Four handle methods [11]

Page 11: Mechanical Comfort

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.

Page 12: Mechanical Comfort

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

Page 13: Mechanical Comfort

Types of mechanoreceptors

  There are seven kinds of mechanoreceptors present in the skin

Page 14: Mechanical Comfort

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

Page 15: Mechanical Comfort

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

Page 16: Mechanical Comfort

Human Skin published by WebMD LLC 2009

Page 17: Mechanical Comfort

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

Page 18: Mechanical Comfort

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]

Page 19: Mechanical Comfort

Fabric deformation [10]

Page 20: Mechanical Comfort

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]

Page 21: Mechanical Comfort

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]

Page 22: Mechanical Comfort

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.

Page 23: Mechanical Comfort

Man in desert Face is fully covered

Page 24: Mechanical Comfort

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).

Page 25: Mechanical Comfort

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

Page 26: Mechanical Comfort

KES Measuring system [14]

Page 27: Mechanical Comfort

KES measuring system[13]

Page 28: Mechanical Comfort

FAST (Fabric Assurance by Simple Testing)

  Developed by The Australian CSIRO

  Alternative of KES, relatively inexpensive, reliable, accurate, robust and simple to operate

Page 29: Mechanical Comfort

FAST System detail [15]

Page 30: Mechanical Comfort

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

Page 31: Mechanical Comfort

Stiffness and bending tester [17]

Page 32: Mechanical Comfort

(a) Image analysis system, (b) Captured image on the drape meter [10] (c) Sharp corner tester [2]

Page 33: Mechanical Comfort

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

Page 34: Mechanical Comfort

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.

Page 35: Mechanical Comfort

  [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.

Page 36: Mechanical Comfort

  [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