Soldier Protective Clothing and Equipment Feasibility of Chemical Testing Using a Fully Articulated Robotic Mannequin (2008) / Chapter Skim
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5 Design Challenge: PETMAN Surface Structure and Materials
5 Design Challenge: PETMAN Surface Structure and Materials
Pages 93-110
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From page 93... ...
3.2.3 The study will determine the feasibility of designing a PETMAN system whose materials of construction will not be significantly degraded by exposure to both traditional chemical agents (T) and Toxic Industrial Chemicals (TICs)
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From page 94... ...
requirements document. THE PETMAN SKIN The major characteristics of the PETMAN skin to meet the PETMAN requirements are breathability, sweatability, physiologic monitoring, resistance to chemical agents, usability, operating conditions, decontamination and disposability, and shape comformability.
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From page 95... ...
3.3.11 The PETMAN system shall be capable of being decontaminated with no adverse effects on the operation of the system and such that there is no effect on the next iteration of test (T) or leaving negligible agent residual, as defined by 3X decontamination level in DA PAM 385-61, Toxic Chemical Agent Safety Standards, (O)
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From page 96... ...
The third layer would be inside the PETMAN surface skin and provide an additional layer of protection to minimize contamination of the PETMAN internals. Table 5.1 shows a comparative analysis of the three skin architectures DA PAM 385–61 Toxic Chemical Agent Safety Standards, 27 March 2002, Department of the Army Pamphlet 385-61, http://www.army.mil/usapa/epubs/pdf/p385_61.pdf, pp.
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From page 97... ...
Internals Outer Skin PETMAN Surface (c) FIGURE 5.1 Conceptual architectures for the PETMAN skin: (a)
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From page 98... ...
Soft Skin In addition to having the characteristics of the PETMAN surface skin, the soft skin must facilitate the deployment of sensors, be easily decontaminated, and provide a surface like human skin for the IPE. An extensive review of the literature on artificial skin has led to the conclusion that developments in alternatives to skin are biological tissue-based and that the resulting structure typically requires a living body to sustain it and continue to grow.
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From page 99... ...
Hence, the design challenge is to investigate and identify polymeric materials that would come close to human skin in physical, mechanical, and chemical properties and would meet the PETMAN performance requirements discussed earlier. During the course of the study, it was difficult to find published data on the physical and mechanical properties of human skin.
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From page 100... ...
Hair Shaft Epidermis mis Stratum Cor Corneum Stratum ger germinativum Dermis Sebaceous Gland Hypodermis Nerve Follicle Sweat Gland FIGURE 5.3 Structure of human skin. SOURCE: Adapted from http://nihseniorhealth.gov/skincancer/faq/faq3b_popup.
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From page 101... ...
are considered below in the evaluation process for selecting suitable materials for realizing the PETMAN soft skin. Some potential candidate materials for the PETMAN soft skin are polyester, nylon, polyurethane, polyurethane in the form of spandex, expanded polytetrafluoroethylene (ePTFE)
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From page 102... ...
When PTFE is stretched rapidly, it becomes a strong, water resistant yet breathable microporous material referred to as ePTFE, which is the key component of GORE-TEX® membrane. The ePTFE structure is combined with an oleophobic, or oil-hating substance that allows vapor to pass through but prevents contaminating substances -- such as body oils, cosmetics, insect repellents, and food substances -- from penetrating. In addition, ePTFE is known to be chemically resistant to virtually all industrial chemicals, including acids, alcohols, aldehydes, amines, bases, esters, ethers, halogenated hydrocarbons, hydrocarbons, ketones, and polyalcohols. Another variant incorporating ePTFE, is the GORE CHEMPAK ®, which combines a chemical protective polymer with an ePTFE.
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H M H H H ePTFE (including its variants) H H H H H Note: L = little or no capability, M = medium capability, H = highest capability or most desirable.
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From page 104... ...
merits the ratings shown in the table in comparison with those for polyester and nylon. Form Factor for PETMAN Soft Skin The PETMAN soft skin can take one of three forms: It can be a coating on the surface skin, for example, using polyurethane; it can be a casting that is bonded to the surface skin with a breathable adhesive; or it can be a form-fitting layer on the surface skin in the form of a fabric or garment, as is the case with NEWTON, the mannequin from MTNW.10 A comparative evaluation of the three options based on a set of critical criteria is shown in Table 5.3.
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From page 105... ...
Form-fitting layer H H M H H NOTE: L = little or no capability, M = medium capability, H = highest capability or most desirable.
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From page 106... ...
Table 5.4 shows the composite ranking of the various combinations of form factor -- casting and a formfitting layer -- and the five choices for materials, including ePTFE and its variants, and polyurethane and its variant spandex. With the powdered form of ePTFE,11 it is possible to produce a casting, but use of ePTFE in a form-fitting membrane would be preferable.
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From page 107... ...
Table 5.4 Soft-Skin Configuration: Form Factor and Materials Analysis Material Options CHEMPAK® Ultra CHEMPAK® Selectively Form Factor ePTFE and Variants Barrier Permeable Polyurethane Spandex Casting M N/A N/A M L Form-fitting layer H H H L H NOTE: L = little or no capability, M = medium capability, H = highest capability or most desirable.
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From page 108... ...
CONCLUSIONS AND RECOMMENDATIONS Analysis of the PETMAN surface requirements and potential solutions to meet the requirements resulted in the following conclusions and recommendations: Conclusion 5-1: The need to simulate the interaction of human skin with the IPE has not been specified in the PETMAN requirements. However, since the PETMAN is conceived of as a surrogate for a sol dier during the evaluation of IPE, it is important for the interaction 12 Service, R
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From page 109... ...
Recommendation 5-1: Simulation of the interaction of human skin with the IPE should be added as an objective PETMAN requirement. Conclusion 5-2: Various methods exist for achieving the threshold and objective PETMAN requirements that include a mannequin surface consisting of multiple layers of skin, such as an inner skin that protects internal mechanical and electrical components and an outer soft skin that is in contact with the IPE.
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From page 110... ...
Conclusion 5-4: Various materials exist for the inner skin to meet the threshold and objective requirements of PETMAN, such as a metal porous skin from Measurement Technology Northwest that perspires and provides zoned heating. Conclusion 5-5: Various materials exist for the outer soft skin in con tact with the IPE, such as expanded polytetrafluoroethylene and poly urethane (spandex)
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