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Article
Publication date: 28 September 2012

M. Grujicic, A. Arakere, B. Pandurangan, A. Grujicic, A. Littlestone and R. Barsoum

Polyurea falls into a category of elastomeric co‐polymers in which, due to the presence of strong hydrogen bonding, the microstructure is of a heterogeneous nature and…

Abstract

Purpose

Polyurea falls into a category of elastomeric co‐polymers in which, due to the presence of strong hydrogen bonding, the microstructure is of a heterogeneous nature and consists of a compliant/soft matrix and stiff/hard nanometer size hard domains. Recent investigations have shown that the use of polyurea as an external or internal coating/lining had substantially improved ballistic‐penetration resistance of metallic structures. The present work aims to use computational methods and tools in order to assess the shock‐mitigation ability of polyurea when used in the construction of different components (suspension‐pads, internal lining and external coating) of a combat helmet.

Design/methodology/approach

Shock‐mitigation capability of combat helmets has become an important functional requirement as shock‐ingress into the intra‐cranial cavity is known to be one of the main causes of traumatic brain injury (TBI). To assess the shock mitigation capability of polyurea, a combined Eulerian/Lagrangian fluid/solid transient non‐linear dynamics computational analysis of an air/helmet/head core sample is carried out and the temporal evolution of the axial stress and particle velocities (for different polyurea augmented helmet designs) are monitored.

Findings

The results obtained show that improvements in the shock‐mitigation performance of the helmet are obtained only in the case when polyurea is used as a helmet internal lining and that these improvements are relatively small. In addition, polyurea is found to slightly outperform conventional helmet foam, but only under relatively strong (greater than five atm) blastwave peak overpressures.

Originality/value

The present approach studies the effect of internal linings and external coatings on combat helmet blast mitigation performance.

Details

Multidiscipline Modeling in Materials and Structures, vol. 8 no. 3
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 1 May 2008

Jin Jiang Chang and Wang Cheng

The fabric construction of the ballistic fabrics used in military helmets is analyzed in this research and the ballistic performance of the fabric construction is…

Abstract

The fabric construction of the ballistic fabrics used in military helmets is analyzed in this research and the ballistic performance of the fabric construction is compared. The advanced compact index Ψz is used in designing the construction of the ballistic fabrics used for military helmets. There is a relationship between the compact index of the fabric and its ballistic performance when this method is selected. Once the compact level of the fabric is grasped accurately, it raises the distinct thinking that antiballistic fabric design and its weavability in relation to the product performance of antiballistic fabric, gives free rein to get twice the results with half the effort. An effective parameter can then be supplied to a Computer Simulation Design to be used as a reference plan to increase ballistic fabric design. The particularity of national defense products which require reducing costs, raising efficiency, performing effective combat and putting into use quickly is addressed. This is a method to improve the performance of current basic materials.

Details

Research Journal of Textile and Apparel, vol. 12 no. 2
Type: Research Article
ISSN: 1560-6074

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Article
Publication date: 8 August 2016

Mica Grujicic, S Ramaswami, Jennifer Snipes, Ramin Yavari and Philip Dudt

The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against…

Abstract

Purpose

The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. In the present work, augmentations of the ACH for improved blast protections are considered. These augmentations include the use of a polyurea (a nano-segregated elastomeric copolymer)-based ACH external coating/internal lining.

Design/methodology/approach

To demonstrate the efficacy of this approach, instrumented (unprotected, standard-ACH-protected, and augmented-ACH-protected) head-mannequin blast experiments are carried out. These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction analysis.

Findings

The results obtained indicated that: when the extent of peak over-pressure reduction is used as a measure of the blast-mitigation effectiveness, polyurea-based augmentations do not noticeably improve, and sometimes slightly worsen, the performance of the standard ACH; when the extent of specific impulse reduction is used as a measure of the blast-mitigation effectiveness, application of the polyurea external coating to the standard ACH improves the blast-mitigation effectiveness of the helmet, particularly at shorter values of the charge-detonation standoff distance (SOD). At longer SODs, the effects of the polyurea-based ACH augmentations on the blast-mitigation efficacy of the standard ACH are inconclusive; and the use of the standard ACH significantly lowers the accelerations experienced by the skull and the intracranial matter. As far as the polyurea-based augmentations are concerned, only the internal lining at shorter SODs appears to yield additional reductions in the head accelerations.

Originality/value

To the authors’ knowledge, the present work contains the first report of a combined experimental/computational study addressing the problem of blast-mitigation by polyurea-based augmentation of ACH.

Details

International Journal of Structural Integrity, vol. 7 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

Content available
Article
Publication date: 1 December 2003

Abstract

Details

Aircraft Engineering and Aerospace Technology, vol. 75 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 September 1917

In the speech in which he introduced the new Education Bill, Mr. H. A. L. Fisher remarked that it did not deal with a number of special questions, “which must be the…

Abstract

In the speech in which he introduced the new Education Bill, Mr. H. A. L. Fisher remarked that it did not deal with a number of special questions, “which must be the matter of another measure.” One of these questions was “libraries,” and we are now definitely face to face with the fact that the Board of Education are of opinion that libraries are within their purview. The report of the speech as it appears in The Times is not conclusive upon the point. “Libiaries,” as an auxiliary of education, may connote in the Minister's mind the mere provision of libraries in schools and teaching institutions generally. If that is so there is no particular reason for alarm, so long as the authorities recognize that even the management of school libraries is a matter for librarians rather than for teachers.

Details

New Library World, vol. 20 no. 3
Type: Research Article
ISSN: 0307-4803

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Article
Publication date: 1 April 1989

The Prime Minister, the Rt Hon Mrs Margaret Thatcher FRS MP, arrived “Just in Time” to open a new one million litre paint distribution centre at the Trimite paint…

Abstract

The Prime Minister, the Rt Hon Mrs Margaret Thatcher FRS MP, arrived “Just in Time” to open a new one million litre paint distribution centre at the Trimite paint manufacturing complex at Uxbridge (Middlesex).

Details

Pigment & Resin Technology, vol. 18 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 7 October 2020

Chih-Hao Wen and Yuh-Chuan Shih

Combining the collected human body variables by a 3D body scanner and the research results of medical computed tomography (CT) imaging, this research aims to develop a…

Abstract

Purpose

Combining the collected human body variables by a 3D body scanner and the research results of medical computed tomography (CT) imaging, this research aims to develop a military bulletproof vest that is both protective and fit. In particular, the protective part must be able to cover the vital human internal organs completely. The results of this research help to make military bulletproof vests of different sizes for Taiwanese male and female soldiers. At the same time, the research results can provide a reference for the industry of making special-purpose clothing.

Design/methodology/approach

17 important human body variables of 988 participants (male: 716, 72.5%; female 272, 27.5%) are used for the analysis. The K-means algorithm firstly builds clusters of different body shapes for both sexes; the silhouette coefficient helps to determine the optimal number of clusters to be six. Thus, the standard size of the bulletproof vest for soldiers is determined. The specifications of the bulletproof vest's inner core and textile vest are calculated for each cluster user. Our research then makes twelve prototypes of the bulletproof vest. After that, 12 subjects are invited to try on the new version (the vest designed in this study) and the old version (the vest currently used) to contrast the differences between the two.

Findings

According to the index of the silhouette coefficient, the optimal number of clusters is determined to be six for both male and female clusters. Therefore, this study has designed six sizes of the bulletproof vest for male and female soldiers in Taiwan. After trying the new and old vests on, the subjects all indicate that the new vest fits better than the old one. In addition, the coverage of the bulletproof vest designed in this study is 94.38% for male users and 92.75% for female users.

Originality/value

The design of bulletproof vests must take note of the fit of the clothing itself and its protective function. Apart from the size design of general clothing only focusing on the human shape exteriorly, the bulletproof vest also needs to pay attention to the relative positions of vital organs inside the human body. Besides, for practical applications, it is quite effective to use the silhouette coefficient to determine the results of cluster analysis. Thus, the value of this research lies in the cross-field combination, enabling the integration of body measurement, data science and clothing design. Generally, bulletproof vests of newly designed sizes can meet the requirements of Taiwan's military. The research results can be used in the development of various military clothing for Taiwanese military personnel. At the same time, the results can be provided to the clothing industry as relevant parameters for designing unique functional clothing.

Details

International Journal of Clothing Science and Technology, vol. 33 no. 3
Type: Research Article
ISSN: 0955-6222

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Article
Publication date: 1 January 1974

A range of 5 basic types of industrial, all purpose, relays offer a choice of ac or dc coils ‐6A capacity. Operating at 2·4VA for ac and 1·2W dc, the D range conforms with…

Abstract

A range of 5 basic types of industrial, all purpose, relays offer a choice of ac or dc coils ‐6A capacity. Operating at 2·4VA for ac and 1·2W dc, the D range conforms with accepted coil power requirements. High impact flame retardant moulding materials, with good insulation properties, are used throughout. Plug‐in types, with either solder or screw‐terminal sockets and panel mounted types suitable for either termination or Faston connectors, are both supplied with a clear polycarbonate clip‐on dust cover. A narrow profile of both the 2 pole and 3 pole plug‐in versions enables close stacking and consequently space saving with additional uniformity of appearance when mounted on an equipment panel.

Details

Aircraft Engineering and Aerospace Technology, vol. 46 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 13 June 2016

M. Grujicic, S. Ramaswami, J. S. Snipes, R. Yavari and P. Dudt

The design of the Advanced Combat Helmet (ACH) currently in use was optimized by its designers in order to attain maximum protection against ballistic impacts (fragments…

Abstract

Purpose

The design of the Advanced Combat Helmet (ACH) currently in use was optimized by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. The paper aims to discuss this issue.

Design/methodology/approach

In the present work, an augmentation of the ACH for improved blast protection is considered. This augmentation includes the use of a polyurea (a nano-segregated elastomeric copolymer) based ACH external coating. To demonstrate the efficacy of this approach, blast experiments are carried out on instrumented head-mannequins (without protection, protected using a standard ACH, and protected using an ACH augmented by a polyurea explosive-resistant coating (ERC)). These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction finite-element analysis.

Findings

The results obtained clearly demonstrated that the use of an ERC on an ACH affects (generally in a beneficial way) head-mannequin dynamic loading and kinematic response as quantified by the intracranial pressure, impulse, acceleration and jolt.

Originality/value

To the authors’ knowledge, the present work is the first reported combined experimental/computational study of the blast-protection efficacy and the mild traumatic brain-injury mitigation potential of polyurea when used as an external coating on a helmet.

Details

Multidiscipline Modeling in Materials and Structures, vol. 12 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 21 November 2016

Thomas C. Johnson and J. Andrew Hansen

The police response to the protests in Ferguson, Missouri refocused attention on law enforcement agencies’ participation in the military surplus equipment program, or…

Abstract

Purpose

The police response to the protests in Ferguson, Missouri refocused attention on law enforcement agencies’ participation in the military surplus equipment program, or 1,033 Program. Given the extensive media coverage, particularly regarding the acquisition of military vehicles and weapons, it is important to empirically investigate the 1,033 Program. The paper aims to discuss these issues.

Design/methodology/approach

Survey data were collected from 1,205 law enforcement regarding 1,033 Program participation and the types of equipment acquired. This study also explores whether significant differences exist by region, agency type, and size.

Findings

The results demonstrated that while a majority of state and local law enforcement agencies participated in the 1,033 Program, a significant number of agencies did not. Acquisition of military surplus weapons, vehicles, and other types of equipment was not the norm. Significant differences were discerned for overall participation and equipment acquisition based on region, agency type, and size.

Research limitations/implications

This study does not address other concerns such as how surplus military equipment is used or policies agencies may have to govern that use, which provide avenues for further research to discern best practices.

Practical implications

Law enforcement agencies do not appear to acquire military vehicles and weapons to the extent that has been dramatized by the media.

Originality/value

This study contributes empirical data to inform the discussion of law enforcement agencies’ acquisition of military surplus equipment in the USA.

Details

Policing: An International Journal of Police Strategies & Management, vol. 39 no. 4
Type: Research Article
ISSN: 1363-951X

Keywords

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