CW Blog

Pultrusion is one of the most cost-effective processes for manufacturing high-volume composite parts. Most commonly associated with glass fiber-reinforced profiles used in construction and corrosion-resistance applications, tailored pultrusions for automotive applications — including bumper beams, roof beams, front-end support systems, door intrusion beams, chassis rails and transmission tunnels — were highlighted as a key area for growth by the European Pultrusion Technology Association (EPTA, Frankfurt, Germany) in its 2018 World Pultrusion Conference report.

Two commercial launches highlighted at CAMX 2018 (Oct. 16-18, Dallas, TX, US) seem to confirm this technology/market fit. L&L Products, Inc. launched its Continuous Composite Systems (CCS) pultrusions, which use polyurethane resin for automotive applications such as side sills and crash structures. Designed to replace traditional metal structures that require bulkheads for necessary stiffness, CCS pultrusions offer light weight — 75% less mass than steel and 30% less than aluminum — at an economic price. Continuous fiber profiles include three variations: CCS Set using glass fiber, CCS Hybrid using a customized mix of glass fiber and carbon fiber, and CCS Extreme using only carbon fiber. A short-fiber version co-extruded with adhesive comprises a fourth product, CCS Co-Ex. The three continuous-fiber products may also be combined with L&L’s adhesives as part of the company’s in-line processing, further reducing manufacturing costs and time-to-delivery. Beyond automotive, CCS products are also aimed at wind turbine blade spar caps and industrial and architectural applications.

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Composite materials and innovations are constantly evolving. In addition to industry news, features, blog posts and podcasts, CW also maintains a comprehensive collection of product announcements provided by companies. This roundup includes links to regular posts concerning the latest products of interest to the composites industry.

Recent innovations include:

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Those familiar with mechanical testing of composite materials are well aware of the challenges associated with proper testing and accurate measurement of their mechanical properties. To date, many of my columns have focused on such challenges associated with specific types of tests performed with composite materials. In this column, we explore ways to determine whether the properties obtained from mechanical testing of composites are correct — or even reasonable. We’ll focus on the more fundamental types of mechanical tests performed on unidirectional fiber-reinforced composites to measure their stiffness and strength properties.

Stiffness properties, also referred to as elastic properties, include the modulus of elasticity E, the shear modulus G and Poisson’s ratio ν. For isotropic materials such as metals and plastics, stiffness properties are independent of material orientation and thus only one value exists for each of these three stiffness properties. In contrast, the stiffness properties of unidirectional fiber-reinforced composites are highly dependent on the fiber orientation relative to the applied force. To fully characterize the material stiffness of composites, tests must be performed at three mutually perpendicular material orientations relative to the applied loading, resulting in three values for each stiffness property (Fig. 1). However, when multiple layers of 0° prepreg are cured together to make a multilayer unidirectional composite, the random distribution of fibers between the layers causes transverse isotropy in the plane perpendicular to the fiber direction (the 2 and 3 directions shown in Fig. 2). This causes the material to have the same stiffness when pulled in either a horizontal or vertical direction, making several of the stiffness properties redundant. So, of the nine stiffness properties for a unidirectional composite material, the number of independent stiffness properties that must be measured may be reduced to five if the unidirectional composite is assumed to be transversely isotropic1 (Fig. 2).

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In March 2018, a drinking water supply pipeline in the Nassaukade quarter in central Amsterdam unexpectedly collapsed, along with part of a canal wall. The 50m-long, 600-mm-diameter pipe was a vital part of the city’s infrastructure, delivering potable water to many households in the historic city center.

“The customer initially thought that a new pipe would need to be installed,” says Ton van Geest, research and development manager of pipe relining specialist Insituform Europe (Zoetermeer, The Netherlands) at the time of the project (Insituform is now owned by Aegion, St. Louis, MO, US). “However, they realized this involved major, lengthy construction in a very busy and congested part of the town.” Also, the soil underneath the historic quarter of Amsterdam is relatively soft, and construction projects can be complex to avoid damage to the surrounding historical buildings.

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Today I had the privilege of being among about 500 eager people gathered in the early winter cold of the Mojave desert in California to watch the launch of SpaceShipTwo (SS2) by The Spaceship Company (TSC, Mojave, CA, US), a part of Virgin Galactic (VG, London, UK). (See the December CW story, “Leveraging composites for space tourism”).

TSC President Enrico Palermo and VG founder Richard Branson shared the stage as they expressed their hope and confidence in a smooth and successful launch. And that’s what it turned out to be.

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