Automotive Structural Applications Research Articles

Creep behavior of a continuous strand, swirl mat reinforced polymeric composite in simulated automotive environments for durability investigation: Part II: Creep-deformation and model development

Creep deformation behavior of an isocyanurate base polyurethane matrix with a continuous strand, swirl mat E-glass reinforcement was investigated for dimensional stability in automotive structural applications. Experimental data were generated in various simulated automotive service environments and analyzed to develop engineering models. Test results showed that environment had substantial effects on the creep deformation properties. Creep deformation design guide lines with respect to temperature, stress level and time have been proposed, environmental reduction factors for creep deformation suggested for automotive structural design applications.

Creep behavior of a continuous strand, swirl mat reinforced polymeric composite in simulated automotive environments for durability investigation: Part I: experimental development and creep-rupture

Experimental methods were developed to simulate automotive environments and investigate the creep-rupture behavior of an isocyanurate base polyurethane matrix with a continuous strand, swirl mat E-glass reinforcement. The material under stress was exposed to various simulated automobile service conditions to test its creep-rupture properties. Results showed that environment had substantial effects on its creep strength durability. The resulting data were analyzed for deriving experimental based equations. Proposed guidelines and stress reduction factors were developed for automotive structural design applications.

Durability-based design criteria for a chopped-glass-fiber automotive structural composite

This paper describes durability-driven design criteria developed for the use of a chopped-glass-fiber polymeric composite in automotive structural applications. The composite, which was made by a rapid molding process suitable for high-volume automotive applications, consisted of a chopped-fiber E-glass mat, made by the programmable powder preform process (P4), in a urea/urethane matrix. The durability issues addressed include the effects of cyclic and sustained loadings, temperature extremes, and automotive fluid environments. The paper briefly describes the laboratory tests, summarizes the results, and explains how the experimental information was used to formulate coherent and practicable design criteria. The criteria include design analysis guidance, a biaxial strength criterion, time-independent and time-dependent allowable stresses, and rules for assessing cyclic loadings. Environmental degradation factors and the degrading effects of prior loadings are included.

Properties of austenitic Fe-25Mn-1Al-0.3C alloy for automotive structural applications

Austenitic Fe-25Mn-1Al-0.3C steel, cold-rolled and annealed at about 800 °C, exhibited 2.5 times higher tensile strength than current automotive ferritic sheet steel, while possessing comparable formability. The formation of strain-induced deformation twinning gave rise to an optimum combination of high strength and good formability.

Polymer Composite Characterization for Automotive Structural Applications

This paper addresses the need to create new test methods pertinent to automotive structural application and standardize the existing test methods. Ten cases in point are briefly discussed. A list of selected tests has been proposed covering static short-term properties as well as long-term durability properties.

Continuous Ceramic Fibres

Continuous ceramic fibres have many unique properties, including high-temperature durability and high elastic modulus. Their properties make them particularly valuable for use in metal and ceramic composites for automotive, aerospace, and heat-management structural applications. This paper reviews the various fabrication methods used to make ceramic fibres and the properties of many of the oxide and non-oxide continuous fibres that are commercially available or in development. Their low elongation to break sometimes makes fibre-processing techniques such as weaving and braiding difficult. Important applications, particularly composite reinforcement, continue to drive the development of processing techniques to make composite preforms and other fibre structures.

Status Report on High-Strength SMC Composite for Automotive Structural Applications

Abstract Six years of production experience have proved high-strength SMC to be an excellent material for heavy-duty automotive parts. New fields for applications with difficult fiber structures will be opened up in the near future.

Interface characterization of metal matrix composites by transmission electron microscopy

Carbon fiber reinforced metal matrix composites (MMC's) are an attractive class of materials for automotive and aerospace structural applications because of their high strength and stiffness to weight ratios and their low coefficients of thermal expansion. Successful development of these new materials demands a thorough understanding of the structure/property/processing relationships and, in particular, a detailed understanding of the fiber/matrix interface since this region strongly influences the final mechanical properties of the system. This interface is affected by many factors including the manufacturing method, heat treatment, matrix alloy composition and wettability of the fibers but, since it is a region which is typically much less than lμm wide, it is inaccessible to direct detailed observation by any means other than transmission electron microscopy.

Evaluation of woven fabric composites for automotive applications

This paper summarizes the results of a recent study [1] funded by the National Science Foundation to investigate the feasibility of woven fabric composite materials for automotive applications. By identifying the advantages and limitations associated with woven fabric composites and by comparison with current automotive materials, the potential for successful application of these materials is investigated. In particular, strength, fatigue, moldability, and cost effectiveness have been identified as critical indicators of the potential for these materials in automotive applications. The results of an experimental evaluation of the static and fatigue properties of woven composites and comparable unidirectional tape composite laminates are discussed. An analytic model designed to quantify the effect of fabric weave configuration on relative conformability to complex geometries is also presented. Preliminary component designs utilizing woven fabric composites are considered in terms of potential weight savings, potential fabrication methods, and projected cost effectiveness. Finally, the key factors impeding the successful implementation of these materials in particular automotive structural applications are identified and reviewed.

The potential for composites in structural automotive applications

The primary use of fiber-reinforced composites in automobiles, with the exception of a few specialized low volume vehicles, has been in semi-structural or decorative parts. Use of composites in primary structural areas of the vehicle, such as body structures, has been very limited to date. Such applications offer a tremendous opportunity for future expansion of composites in the automotive industry. In addition to materials cost, there are two over-riding criteria for significant application of FRP materials in automotive structures: (1) proof of structural functionality/durability; and (2) development of rapid, reproducible fabrication procedures to optimize manufacturing economics. From a structural viewpoint, there are two major categories of material response which are critical to the application of composites to automobiles: fatigue (durability) and energy absorption. An abundance of evidence is accumulating relating the functional properties of these materials in simple structures. It is clear that the fundamental requirements of energy absorption and fatigue resistance are satisfied by composites and the main challenge is to translate these capabilities into complex structures with less well-defined load inputs. The less quantifiable, but equally important, functional requirement of ride quality (usually defined in terms of noise, vibration and ride harsness, NVH) also appears to be attainable through the utilization of composites. Even though this factor has been historically related to vehicle stiffness, and composite materials are less stiff than steel, all the indications are that the effective stiffness of composite structures meet NVH requirements—the elimination of joints through part integration plays a critical role in achieving such synergistic effects. Many of the properties of composite structures depend on the control of fiber location and part integration which in turn are a direct fucntion of the fabrication process. Current high production rate fabrication processes such as compression molding of sheet molding compound (SMC) type materials go only part way to optimizing the properties and economics. Optimum automotive composite structures will probably require a combination of processes, some of which will need significant development, to realize the enormous potential for composites in the automotive industry. Full-scale structures may involve SMC type molding, thermoplastic stamping and the developing preform molding (HSRTM) process which hasm perhaps, the greatest potential of all the processes of revolutionizing the use of composite structures. Technological breakthroughs in fabrication technology do not appear to be necessary, the main requirement is the development of existing assorted techniques combined with a concerted effort by all aspects of the composite and automotive industry.