John M. Henshaw

An Overview of Recycling Issues for Composite Materials

A review of the major issues surrounding the postuse disposal of polymer composite materials is presented. Composites are compared to unreinforced plastics in terms of production volume and the technologies available for reprocessing. Not surprisingly, composites comprise a very small fraction of the plastics waste stream. In highvolume applications such as automobiles, however, there are reasons to be concerned about composites recycling. The fundamental categories of dealing with waste (burning, burying, reusing, or using less in the first place) are described in relation to plastics and composites. Reprocessing technologies with applications for composites are reviewed. For thermosetmatrix composites, processes involving regrinding waste materials and using them as filler for other polymer processes show promise. For thermoplasticmatrix composites, processes involving grinding and remolding by injection or compression molding are promising. Applications for recycled composites, without which reprocessing is futile, are also reviewed.

Integrating Courses in Marketing Research and Engineering Design: An Instructional Technique for Enhancing the Product Development Process

The integration of undergraduate marketing research and engineering design courses is discussed, and the nature of and need for such integration is established as vital to new product development. Individual courses in marketing research and engineering are described, and the objectives of integrating the courses and plans for implementation are presented. Critical issues for success are revealed.

Finite element analysis of ply-by-ply and equivalent stress concentrations in composite plates with multiple holes under tensile and shear loading

The finite element method is employed to analyze the stress concentration effects of multiple holes in laminated composite plates. The analysis considers the composites both as homogeneous orthotropic plates producing an equivalent property solution, and as laminates consisting of laminae of various orientations, each having its own stress concentration. Theoretical verification of special cases of the analyses are described. Finite element results for [0±45/0]2s and [0 + 45/90]2s laminates loaded in tension or shear are presented. The results are condensed into ‘design curves’ to allow the designer to estimate stress concentrations. These curves allow comparison of stress concentrations on a lamina or laminate basis, for tension or shear, and for the number, size and relative position of holes. It is concluded that the presence of multiple holes tends to increase stress concentration over that which it would be if there were only one hole. Certain sizes and locations of holes also tend to increase stress concentration.

Failure of automobile seat belts caused by polymer degradation

Abstract This paper analyzes the failure of a particular brand of automobile seat belts. The failures described were part of what nearly became the most expensive and widespread automobile recall in U.S. history, affecting about 8.8 x 10 6 vehicles and with a potential total cost of U.S.

A pressure vessel fracture mechanics study of the aluminum beverage can

10 9 . The failures were caused by the degradation and fracture of the seat belts’ polymeric release buttons. When fragments break away from the buttons, they can become lodged within the seat belt mechanism in a variety of locations, such that any one of three distinct failure mechanisms can result: (1) the belt fails to latch, (2) the belt will latch but will not unlatch, and (3) the belt appears to be latched but is not. The seat belt mechanism, and the ways in which the degraded button can cause it to fail, are described in detail. The buttons themselves were found to have been injection molded of ABS and to have undergone photo-oxidative degradation. This degradation process is documented and described. Conclusions from the analysis and lessons learned from the failures are described, along with the auto industry|s short- and long-term solutions to the problem.

Analysis of a blow-molded HDPE bottle that failed by brittle fracture

Abstract Two fracture mechanics studies were conducted using two different aluminum beverage containers (wall thicknesses of 0.0044 in. [0.112 mm] and 0.0039 in. [0.099 mm]). The first study involved a 1.25 in. (31.75 mm) wide center-cracked panel specimen to measure the axial fracture resistance of the containers. Factors contributing to beverage container fracture resistance are discussed, including the thickness and rolling direction orientation. Due to the extremely thin nature of these containers, a reduced specimen thickness leads to a reduced fracture resistance. This resistance is also seen to increase as the orientation to the material rolling direction becomes perpendicular. The second study was a full-scale, leak-before-break rupture test. Each container had a crack of a known length and depth machined in the exterior wall. The stress intensity factor of these cracks upon failure gives excellent correlation to the center-cracked panel specimens as well as to other models for predicting pressure vessel rupture.

Composite design and manufacturing critiquing system

Abstract A blow molded high density polyethylene (HDPE) bottle [volume 1 US gallon (3.79 l)] failed due to cracks in its bottom surface. The bottle had contained a solution used for cleaning heat exchanger coils that contained, among other chemicals, hydrofluoric acid. Failure of the bottle destroyed a set of steel shelves and some associated equipment and necessitated an expensive cleanup. The bottle was examined in order to determine the cause of failure. Failure was attributed to an abnormally high level of crystallinity in the failed bottle, which caused the HDPE to be brittle and crack under a light impact load.

Effect of gel modulus on the porosity of low-density silica

An ongoing research effort is consolidating material and process knowledge in a critiquing system dealing with fuzzy criteria to aid designers in evaluating the incorporation of composite materials into their design. The extent of knowledge required to perform the task of evaluating composite processes and materials is often beyond the expertise of many design engineers as they lack understanding of the nature of composite material manufacturing. The system under development is known as the Composites Design and Manufacturing Critiquing System (CDMCS). The CDMCS critiques a submitted design through interaction with the user. An account of the strengths and weaknesses of the design is supplied to the user through the facilities. The current focus of the system is on process selection, but the system is generic so that other aspects of composite material manufacturing may be included. The system is implemented in Macintosh Common LISP. This article describes the features of the system that have been implemented. The system is currently being extended to cover more than the primary process component of the domain.

Design and Development of a Portable Off-Grid Water Chlorination System

Abstract The extent of shrinkage that occurs during the early stages of ambient pressure drying (APD) of silica gel is greatly affected by the stiffness of the silica network. This parameter was manipulated through modification of the second step of the two-step acid–base process. The modulus of the gel, which was measured with a new technique based on the compression of rod-shaped specimens, decreased to roughly the same extent by increasing the gel volume (through the addition of extra ethanol or water) or by decreasing the amount of base added. However, following APD and calcination, these modifications resulted in quite different pore volume distributions. In general, the pore volume corresponding to large and intermediate mesopores decreased with increasing gel volume; however, a uniform pore volume distribution (possibly due to localized rupture of the silica network during drying) was observed only with the addition of ethanol. Decreasing the amount of ammonium hydroxide produced the greatest loss of large and intermediate mesopores; this observation amplifies the importance of the highly branched silica clusters, created through the addition of base, to the stiffness of the gel.

On the Design of a Vertical Axis Wind Turbine for Use in Rural Communities

The design and fabrication of a portable water chlorination system is described. The backbone of the system is a custom-designed, efficient, and easily operated chlorine electrolysis cell. The cell produces concentrated hypochlorous acid (HOCl), a form of chlorine that readily kills harmful pathogens in untreated water. The cell is fabricated from durable yet inexpensive materials and requires only two inputs: (1) 12 volts of direct current, which can be supplied with standard car batteries that are commonplace worldwide, and (2) 800 milliliters of 0.43 molar sodium chloride solution, which can be substituted with seawater. The system was first tested in the laboratory under controlled conditions. The cell was powered for 70 minutes and samples of the solution were taken in 10-minute intervals. The hypochlorite ion (OCl− ) concentration was measured with a UV-visible light spectrophotometer. The results show that the cell produces enough hypochlorite in one hour to disinfect up to 1500 liters of clear surface water or 750 liters of turbid water. Successful laboratory test results led to field tests utilizing a solar photovoltaic power supply. Preliminary results of these tests are presented.Copyright