Viscous criterion and its relation with the projectile-thorax energy interactions

Despite many injury criteria to measure thoracic trauma in known engineering parameters, viscous criterion, that is a product of maximum instantaneous velocity of thorax deformation and maximum instantaneous chest compression, has been widely used. Using Lobdell mathematical model of the thorax, Wang [1] has carried out analytical studies and proved that peak viscous response is related to the peak energy storing rate of the thorax and also proved that it does not related to viscosity of the thorax. Authors have carried out a scholastic study by impacting a FE model thorax MTHOTA (Mechanical THOrax for Trauma Assessment), which is fully validated for blunt ballistic impacts, with a foam nose projectile with speeds of 30 – 90 m/s with an increment of 5 m/s. VCmax values and projectile – thorax energy interactions were evaluated and presented in this paper. From the outcome of the simulations, relation between maximum stored energy

Fibre composites for high pressure pipeline repairs, in-air and subsea: an overview

In 2001 it was reported that in North America alone, corrosion to the Oil & Gas pipeline distribution network cost approximately $2-3.3 billion per annum with 10% of that cost being associated with actual failure of the pipeline. In addition pipelines are also susceptible to erosion and mechanical damage producing further losses in pipe structural integrity. This results in high maintenance costs, possibility of adverse environmental consequences and the costly interruption to product transportation and distribution. The cost and technical challenges of adequately addressing repair are significant and greatly increase for underwater applications particularly with increasing water depth. It therefore induces the need of searching for alternative repair techniques involving new advanced materials for ease of installation and application against adverse environmental effects in the long run. Fibre composite materials provide excellent advantages over conventional metals in engineering practices for many decades. These advantages make fibre composite suitable candidate for effective repair technology. This paper provides a comprehensive review on the recent development and future prospect of using these materials for in-air and underwater pipeline external repairs. Various aspects of technical knowhow; benefits and shortcomings of the repair considerations are also presented

Effect of energy absorbing mechanisms on the blunt thoracic trauma caused by ballistic impacts

military and law enforcement officials have been using kinetic energy non-lethal weapons ranging from rubber bullets to projectiles with foam in situations which do not warrant the usage of lethal force. On many occasions, non-lethal projectiles have caused serious injuries. Therefore, a scholastic study was carried out to see the effect on the injury caused by the projectiles embedded with various energy absorbing mechanisms. Projectile – target interaction (kinetic energy transfer or energy gained by the target and Total energy of the projectile) plays a vital role in understanding the effect of the projectile on the target. Therefore, to evaluate the effect of the energy absorbing mechanisms on the blunt thoracic trauma, target considered should emulate the human thorax as far as the projectile-thorax interaction is concerned. A fully validated FE model of the thoracic surrogate (FE model of the MTHOTA surrogate of the thorax, which is validated with the human response corridors developed by Wayne State University’s researchers) was impacted with a typical foam nosed projectile at a speed of 90 meters per second. A collapsible Aluminum foil attached to the hollow foam nose of the projectile and impact simulations were carried out for different thicknesses of the foil (0.3 mm and 0.5 – 4.0 mm with an increment of 0.5 mm). To nullify the effect of the variation in the mass and also for effective comparison, impact speed was adjusted so that kinetic energy of the projectile remain same for all analyses. For the design of the collapsible mechanisms considered for the study, foil thickness less than 2 mm, though foiled structure got collapsed it didn’t absorb considerable amount of energy. More than 2 mm thickness, foil didn’t collapse properly and whole projectile acted as stiff/solid round and produced more injury. Dynamic force response, dynamic displacement response, effect of the aluminum foil on the thoracic injury in terms of VCmax etc., were presented in this paper

Review of anthropomorphic test dummies for the evaluation of thoracic trauma due to blunt ballistic impacts

Biomechanical responses of the thoraces of finite element models of 4 Anthropomorphic Test Dummies (namely, LSTC Hybrid III deformable, LSTC Hybrid III rigid, LSTC/NCAC Hybrid III and ES-2re) were reviewed by impacting them with the 140 gram wooden projectile with impact speeds of 20 and 40 m/s, and 30 g wooden projectile with 60 m/s. In order to elucidate the usefulness of the ATDs for evaluating blunt thoracic trauma caused by blunt ballistic impacts (projectile mass 20 – 200 gram, velocity 20 – 250 m/s), responses obtained were compared with the human response corridors developed by Wayne State University’s researchers. It was evident that none of the thoraces exhibited bio-fidelity for the impact cases considered for the analysis. Thoraces of former three dummies found to be very stiff and the latter yielded realistic responses but Viscous Criterion (VCmax) values based on the deflection response were way higher when compared to those obtained from the cadaveric experiments for the similar impact conditions. Values of viscous criterion (VCmax), probability for AIS3+ and AIS4+ injuries based on the maximum rib deflections (only for the ES-2re dummy for particular impact locations), were found to be, for some cases, to a certain extent, in agreement with those obtained from the cadaveric experiments. The present study highlights the unsuitability of the numerous thorax models (both physical and finite element), while necessitating the development of the thorax surrogate with an acceptable biofidelity. Such biomechanical surrogate of the thorax, for the evaluation of trauma, is essential for the validation of non-lethal ammunition, development of bullet proof vests and chest protectors for the athletes of collision & contact sports

Evaluation of the blunt thoracic trauma due to baseball impacts – review of the Blunt Criterion

Evaluation of the thoracic injury due to blunt impacts during the contact and collision sports activity is crucial for the development and validation of the chest protectors and safety solid sports for the athletes. In the case of young athletes, proper chest protectors can avoid not only severe chest trauma but also protect them from the sudden death due to commotio-cordis. In order to evaluate the thoracic injury in terms of known engineering parameters (Viscous Criterion), non-linear finite element simulations were carried out by impacting FE model of the thorax surrogate (MTHOTA- Mechanical THOrax for Trauma Assessment) with a synthetic baseball and a synthetic baseball of the same size and weight at the impact speed of 10 – 45 m/s (with an increment of 5 m/s). Synthetic baseball and soft-core baseball produced VCmax = 1 m/s at the impact speed of 27.9 m/s and 30.7 m/s respectively. For both sports ball impact cases, Blunt Criterion (which is commonly used as non-lethal munitions design criterion that takes only kinetic energy of the projectile and weight & geometry of the thorax into consideration) was evaluated for all impact cases of two types of baseballs. Results have revealed the projectile specificity of the Blunt Criterion

Characteristics of a silk fibre reinforced biodegradable plastic

Silk fibre is one kind of well recognized animal fibres for bio-medical engineering and surgical operation applications because of its biocompatible and bio-resorbable properties. Recently, the use of silk fibre as reinforcement for some bio-polymers to enhance the stiffnesses of scaffolds and bone fixators has been a hot research topic. However, their mechanical and biodegradable properties have not yet been fully understood by many researchers, scientists and bio-medical engineers although these properties would govern the usefulness of resultant products. In this paper, a study on the mechanical properties and bio-degradability of silk fibre reinforced Poly (lactic-acid) (PLA) composites is conducted. It has been found that the Young’s modulus and flexural modulus of the composites increased with the use of silk fibre reinforcement while their tensile and flexural strengths decreased. This phenomenon is attributed to the disruption of inter- and intra-molecular bonding on the silk fibre with PLA during the mixing process, and consequent reduction of the silk fibre strength. Moreover, bio-degradability tests showed that the hydrophilic properties of the silk may alter the biodegradation properties of the composites compared to that of a pristine PLA sample

Development and validation of a thorax surrogate FE model for assessment of trauma due to high speed blunt impacts

Without being able to evaluate blunt thoracic trauma in terms of an acceptable injury criterion, it is not possible to develop or validate non-lethal projectiles, bullet proof vests and chest protectors for sports personnel etc. In order for the assessment of the blunt trauma caused by high speed projectiles, a novel design of a mechanical surrogate of the thorax (Mechanical THOrax for Trauma Assessment: MTHOTA) was conceptualized. An iterative impact analyses in the virtual testing environment were carried out by impacting the finite element model of the mechanical thorax with 37 mm diameter, 100 mm long wooden baton weighing 140 grams (20 m/s and 40 m/s impact speeds) and 37 mm diameter, 28.5 mm long wooden baton weighing 30 grams with 60 m/s impact speed. From the output of every simulation, force dynamic response (force-time), deflection dynamic response (deflection-time) and force-deflection response were elicited and compared with the corresponding human response corridors developed by Wayne State University’s researchers. By suitably changing the design parameters of the mechanical surrogate, simulation iterations were continued till the responses were correlated with the human response corridors. Values of viscous criterion (VCmax), product of maximum chest deflection and the rate at which chest deforms, obtained from MTHOTA were in very good agreement with those obtained from the cadaveric test data. The methodology, concept and validation of the MTHOTA have been presented in this paper

Glass fibre and recycled mixed plastic wastes: recent developments and applications

In recent years, there has been an increasing interest in seeking for potential civil engineering applications of recycled mixed plastic wastes to relieve the pressure on landfills. This paper presents the recent developments on new generation of composites made from mixed recycled plastics and glass fibre. Glass fibres are one of the most cost-effective reinforcements which can be compounded with recycled thermoplastics to obtain products with improved mechanical property. Some of the first uses for such composites are for the replacement for traditional wooden items like park benches and picnic tables. While these composites are appropriate for such small-scale products, using them in structural applications would consume much greater volume of waste plastics. With its inherent resistance to rot and insect attack, these composites can in fact be used as a replacement for chemically treated timber in various large scale outdoor applications such as railroad crossties and bridges. However, the behaviour of such composites under different environmental conditions such as elevated temperature and ultraviolet rays are crucial. This paper provides an overview of the on-going efforts to address the critical issues for the effective usage of recycled mixed plastics composites in civil engineering and construction

Introduction to multifunctional polymer nanocomposites

The nano era, similar to the mid-industrial steel era, not only stands for great technical innovations but also indicates the future trend of existing technologies. It is believed that this period will dominate and transform people's daily lives. 'Nano' is a unit of length defined as 10-9 m. To give you an idea of how small it is, the width of a human hair is 10-6 nm, and the size of an atom is 0.1 nm. In recent decades, the development of microscopes has enabled scientists to observe the structures of the materials at nanoscale and investigate their novel properties. In the early 1980s, IBM (Zurich) invented the scanning tunneling microscope, which was the first instrument that could 'see' atoms. In order to expand the types of materials that could be studied, scientists invented the atomic force microscope. Now, these instruments can be used to observe the structures and different properties of materials at nanometer scale. Physics reveals big differences at the nanometer scale, and the properties observed on a microscopic scale are novel and important. For example, quantum mechanical and thermodynamic properties have pushed forward the development of science and technology in the 20th century. Nanotechnology means the study and application of materials with structures between 1 and 100 nfn in size. Unlike bulk materials, one can work with individual atoms and molecules and learn about an individual molecule's properties. Also, we can arrange atoms and molecules together in well-defined ways to produce new materials with amazing characteristics. For example, nanotechnology has produced huge increases in computer speed and storage capacity. That is why 'nano' has attracted attention in the research fields of physics, chemistry, biology, and even engineering. This word has entered the popular culture and can be found in television, movie, and commercial advertisements. Politicians and leaders around the world have realized the importance and urgency of developing nanoscience and nanotechnology, so countries have promoted research in nanoscience and nanotechnology in their universities and laboratories. With the huge increase in funding, scientists are pursuing nano research intensively, and the rate of discovery is increasing dramatically

Interfacial bonding in a nanoclay/polymer composite

In this study, X-ray photoelectron spectroscopy (XPS) was conducted to analyze the chemical composition between epoxy matrix and nanocomposite. This experiment revealed that a chemical bonding at an interface between the matrix and nanoclay of the composites did exist. Thus, such bonding can enhance the mechanical and thermal properties of resultant polymer composites as reported in many literatures