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Building on broad discussions between many universities, this paper presents a research agenda based on a holistic, comprehensive view of the issues. It proposes that our infrastructure is a system of systems involving different technical manifestations and social organisations. The implication is that we need a fundamental reconsideration of how we look at system design, away from traditional disciplinary considerations and toward a multi-domain, multi-disciplinary effort. To this end, it proposes an agenda of: comparative analyses across infrastructures and political structures, that would identify commonalities and larger lessons; creation of integrated socio-technical models that usefully describe the interactions between the technical infrastructure and its social context; methodological efforts, aimed largely at capturing the network characteristics, both technical and social, of the infrastructure system of systems; explicit testing and evaluation of the research through programs of collaboration with practitioners and governmental organisations.

This paper investigates the nature of collaboration in eight small technology-innovating firms who participated in the US Government sponsored SBIR (Small Business Innovative Research) process in 1995/6. The research was performed in 2003 allowing sufficient time to assess the relative success of various practices by the firms following differentiated SBIR processes. Following expectations, all of the firms participated in extensive collaboration. However, in contrast to earlier work studying the same firms in 1998/9, it is found that a SBIR process initiative designed to encourage collaboration with other entities and to accelerate commercial success ("Fast Track Process") had no influence on whether the firm had commercial and employment growth success. It appears that much of the identified collaboration is due to the need of small firms to extend their understanding of the broader systems implications of the technology they are developing. The paper also describes some perceptions held by small firms about reasons not to collaborate.

This paper briefly reviews the various available types of high-strength steels — conventional, recovery-annealed, and dual-phase steels. A judgmental analysis of a large number of stamped automotive components shows that dual-phase steels, with their superior strength at a given elongation (formability), offer the best potential for weight savings. The rest of the paper concerns the physical metallurgy and mechanical response of dual-phase steels. It is shown that strength is a function of the percent martensite in the structure, although the strength is less than predicted by a simple rule of mixtures. The enhanced ductility of dual-phase steels is shown to be a consequence of the high s train-hardening rate observed in these steels, the reason for which is not well understood but probably reflects the properties of the ferrite matrix. The strain-rate sensitivity of dual-phase steels is found to be higher than that of conventional high-strength steels of comparable tensile strengths. Fatigue studies of dual-phase steels show them to be comparable to conventional high-strength steels in the notched condition; energy absorption during the axial collapse of tubes is shown to be solely a function of tensile strength. Also included are data on the temperature dependence of tensile strength in both the notched and unnotched conditions; high-strength dual-phase steels exhibit notch sensitivity even at room temperature. A study of formability (springback) shows that high-strength dual-phase steel is slightly worse than SAE 950X but much better than SAE 980X steel.

The specific energy absorbed during uniaxial tension and during axial compression of cylindrical tubes with various wall thicknesses and diameters has been measured for 1015 steel in two heat treatment conditions and for 6061 aluminum alloy in four heat treatment conditions. For axial compression of tubes, the energy absorbed/unit weight, Esc, is a function of the thickness to diameter ratio and the present work shows that for 0.02 < t/D < 0.1, the dependence is well described by a power law of the form Esc = A(t/D)m where m varies between 0.5 and 1.0 for different materials. A salient finding is that the ranking of materials for specific energy absorption depends upon the testing mode. In tension, it is shown that density ρ, ultimate tensile strength σult and the uniform elongation, εu are significant in the ranking of materials. Specifically, the present and previous results show that the energy absorbed/unit weight, depends upon both the ultimate tensile strength σult and the corresponding true (tensile) strains εu, EsT = σult εu/ρ(1 + εu). In axial compression, however, the measured variations in Esc (for a fixed geometry) with the different materials show that Esc is simply proportional to the specific ultimate tensile strength (σult/ρ). The magnitude of the tensile uniform elongation is unimportant in ranking materials for this compression collapse mode because the geometric instability present in tension tests does not arise in the plastic buckling process that occurs during the axial compression of cylinders.

The maximum loads sustainable in both four-point bending and prebent hinge collapse tests of several materials have been determined at crosshead rates from 4.2 × 10−3 mm/s to 4.2 m/s (10−2–104 in./min). All the materials exhibit a logarithmic dependence of flow stress on crosshead rate; this dependence is consistent with that previously reported for tensile deformation. Although there are some minor differences in the dynamic stress factors obtained by the bending and tensile methods, all the methods rank the materials in the same order. Thus, for materials evaluation the most convenient test method, which is usually the tensile test, can be chosen. For more complex loading geometries than considered here, scale model testing would yield the most reliable results.

The tensile strength of seventeen engineering materials including steels, Al alloys, and fiber-reinforced plastics, has been determined at strain-rates from 10−3 to 103 sec−1. Variable effects on the stress-strain behavior were found in the different materials with the Al alloys showing minimal strain-rate sensitivity and the plastics highest. All results exhibit a logarithmic dependence of flow stress on strain-rate and thus the dynamic factors (ratio of dynamic to low rate or quasi-static strengths) are as dependent upon changes in quasi-static testing speed (∼1 in./min (0.42 mm/s) as they are to changes at high speed (50,000 in./min or 50 mph (22.35 m/s). No significant influence of strain-rate on elongation or reduction in area has been found for any of the materials. Steels, which comprise the majority of the presently investigated materials, exhibit a higher rate sensitivity for yielding than for higher strain deformation. It is shown that the flow stress results for these steels leads to an internally consistent scheme when (1) strength level and (2) strengthening mechanisms are properly accounted for.

The most extensive materials substitution program in automotive history—from mild steel to high-strength steel —is currently well underway. The major technical issues affect almost all aspects of vehicle design and production, and this transition involves changing essential characteristics of the major car input material, sheet steel. This paper discusses the recent past, and future potential for high-strength, low-alloy steel applications in vehicles, including metallurgical changes responsible for changes in characteristics, material availability, and approximate relative cost. Implications of changed material properties and trade offs in the key sheet steel fabrication processes (forming and spot welding), as well as effects of HSLA steel use on vehicle design, particularly crush, mechanical durability, and rigidity, are also discussed. The major issues with respect to vehicle design are to delineate the materials which can be used in all components, and the associated weight reduction achieved in applications. At present, the primary factors deterring rapid implementation of HSLA steels are material availability and sheet metal forming.

The temperature dependence of the yield stress and energy absorbing capacity of zinc foam, having a density between 0.05 and 0.07 of that of zinc, was determined over a range of temperatures from 0.1 Tm to 0.7 Tm approximately. With increase in temperature over this temperature range, the yield stress and energy absorbing capacity of the foam at first increased, and then subsequently decreased, above room temperature. At low temperatures,e.g. 0.1 Tm, the foam disintegrated into powder, and the energy absorbing efficiency parameters were high and independent of the foam density. In contrast, at the highest temperatures,e.g. 0.7 Tm, the energy absorbing efficiency parameters were lower and decreased with increase in density. The results are interpreted on the basis of the change in deformation mode which occurs in the zinc matrix of the foam over this temperature range,i.e. the transition from cleavage at the low temperature to plastic flow at the high temperature of deformation.

The compressive flow behavior of Al, Al−7 pct Mg and 7075 Al alloy foams has been determined in structures whose void fraction varies from 0.80 to 0.95 of the total volume. In all cases, a greater than linear increase in flow strength with increase in density was exhibited, indicating that bending stresses within the foam structure are an important feature of the collapse mode. The flow strength did not follow proportionately changes in bulk flow strength in comparisons of either alloy or of heat-treatment conditions. Ancillary tensile and metallographic observations show that this lack of correlation arises because the different foams collapse by different modes with localized fracture becoming dominant in the higher strength 7075 alloy. The energy absorbing efficiency was found to be independent of foam density for all the materials. However, the efficiency was found to be a strong function of the alloy and heat treatment increasing from about 30 pct in Al, to 43 pct in Al−7 pct Mg and to 50 pct in the solution heat treated and aged 7075 alloy. The increase in efficiency occurs because of an increase in the propensity to fracture in the higher strength alloys which introduces the potential for a propagating constant-stress collapse process.

The martensite morphology and austenite flow strength have been determined in a variety of ferrous alloys chosen so that the austenites were paramagnetic, ferromagnetic, substitutional strengthened, and interstitial strengthened. It is demonstrated that two of the most important variables in determining the habit plane (and thus morphology) of martensite in a given alloy are the resistances to dislocation motion in austenite and in ferrite (i. e., martensite). In the wide variety of alloys where martensite with a {259}γ habit plane was observed, the austenite flow strength atMs is greater than 30,000 psi. At lower austenite strengths, either {225}γ or {111}γ habit planes are found depending on the resistance to dislocation motion in ferrite. Thus, {225} martensites are not always found as part of the spectrum between {111} and {259} martensites but only in the cases (e. g., interstitial strengthening) where ferrite is preferentially strengthened relative to austenite. All of the observations are consistent with the idea that the habit plane observed in a given alloy is the one involving the minimum plastic work for the lattice invariant shear.

Using quantitative metallography the average volumes of the martensite plates have been measured in Fe-23.8Ni-0.42C and Fe-28.5Ni-0.4C after varying degrees of transformation. Over a range of volume fraction transformed from 0.07 to 0.55 (the highest volume fraction sample upon which measurements could be made), the average volume of the martensite plates is constant. Fisher’s equation, which predicts a decrease in the average volume by two orders of magnitude over the experimental range of transformation, is not substantiated by the present experiments chiefly because the influence of autocatalysis is neglected in its derivation.

Flow stress measurements at −196°C on Fe-4.8 at. % Sn-C alloys demonstrate that the presence of interstitial carbon markedly increases the stress for deformation by twinning. The flow stress for an alloy with 0.09 at. % carbon is 12.6 Kg/mm2 higher than the flow stress for a carbon-free alloy. This behaviour, which is an exception to the rule that twinning stresses are relatively invariant to solute content, was anticipated because the normal twinning mode in ferrite does not shear all interstitial atoms to proper octahedral sites. In confirmation of this viewpoint, the experimental results were found to be in reasonable agreement with a theoretical estimate of the change in twinning stress that should result from this crystallographic restraint.

The relative susceptibility to plate microcracking of Fe-1.0 to 1.8 wt pct C alloys containing 0 to 5 wt pct Mn, 0 to 8 wt pct Cr, and 0 to 15 wt pct Ni has been investigated. In the binary Fe-C alloys, the crack area per unit volume of martensite increases with increasing carbon content in the range from 1.0 to 1.3 wt pct in agreement with previous work. However, above 1.4 wt pct C, the specific crack area decreases as the carbon content increases due to a decrease in martensite plate length which in turn arises mostly from a habit plane transition from {225}γ to {259}γ. Indeed, when results from all alloys are considered, it is found that the dominant variable affecting microcracking is the martensite plate length. A direct, but less important, influence of carbon content is also found but any effects resulting directly from other solutes (Ni, Cr, and Mn) are negligible. The impingement model for microcracking suggested by Marder, Benscoter, and Krauss8 is examined in further detail. In this way, a rationale is developed for our observations which are in accord with fracture behavior of macroscopic samples.

The structure, deformation mode and flow strength of a widely varied series of Fe-Ni-C alloys has been determined. In alloys with less than 0.3 wt.% carbon, both lenticular-tetragonal martensites and packet-cubic martensites deform by slip at flow strengths determined chiefly by the carbon content. At higher carbon levels, the packet-cubic martensites are significantly stronger because they continue to deform by slip whereas lenticular-tetragonal martensites with the same carbon content deform by twinning. It is suggested that twinning is suppressed in the higher carbon cubic martensites because in these structures all twin variants inevitably carry a large fraction of the carbon atoms into high energy, non-octahedral sites.

The Curie temperature of the austenite, the martensite-start temperature, and martensite morphology have been determined in a series of nil-carbon Fe−Ni and Fe−Ni−Co alloys. For these alloys, austenite ferromagnetism aboveMs is a necessary, but not sufficient, condition for the formation of lenticular rather than packet martensite. In contrast to Fe−Ni alloys where lenticular martensite only forms below ≈O°C, some of the Fe−Ni−Co alloys transform to this structure at temperatures up to ≈200°C. The results support the hypothesis that the resistance of austenite to plastic deformation affects the habit plane and thus morphology of the martensite which forms.

Technological improvement trends such as Moore's law and experience curves have been widely used to understand how technologies change over time and to forecast the future through extrapolation. Such studies can also potentially provide a deeper understanding of R&D management and strategic issues associated with technical change. However, such uses of technical performance trends require further consideration of the relationships among possible independent variables — in particular between time and possible effort variables such as cumulative production, R&D spending, and patent production. The paper addresses this issue by analyzing performance trends and patent output over time for 28 technological domains. In addition to patent output, production and revenue data are analyzed for the integrated circuits domain. The key findings are:1.Sahal's equation is verified for additional effort variables (for patents and revenue in addition to cumulative production where it was first developed).2.Sahal's equation is quite accurate when all three relationships — (a) an exponential between performance and time, (b) an exponential between effort and time, (c) a power law between performance and the effort variable — have good data fits (r2>0.7).3.The power law and effort exponents determined are dependent upon the choice of effort variable but the time dependent exponent is not.4.All 28 domains have high quality fits (r2>0.7) between the log of performance and time whereas 9 domains have very low quality (r20.9), the exponential relationship is not perfect and it is thus best to consider these relationships as the foundation upon which more complex (but nearly exponential) relationships are based.Overall, the results are interpreted as indicating that Moore's law is a better description of longer-term technological change when the performance data come from various designs whereas experience curves may be more relevant when a singular design in a given factory is considered.

Influence du poids du vehicule sur sa consommation de carburant. Estimation du rapport optimal allegement/cout de fabrication. Validite des previsions

A general treatment of the absorption of mechanical energy by the axial collapse of a variety of structural shapes, including tubes, honeycombs and foams is developed which encompasses both the geometry of the structure and also the material properties. The use of the method in the design of load bearing structures in which energy absorption is an additional design function is illustrated. High strength-to-weight ratio materials offer a significant weight saving for energy absorbing components, although such materials may have a reduced tensile ductility. The implications to situations in vehicle crashworthiness are discussed. /SAE/

The symposiumFormation of Martensite in Iron Alloys was sponsored by the IMD Ferrous Metallurgy Committee as part of the Spring Meeting of the Metallurgical Society of AIME held in Las Vegas, Nevada in May, 1970. The papers were presented in three sessions whose chairmen were K. R. Kinsman, D. S. Lieberman, and G. R. Speich.