Bi-Material Negative Thermal Expansion Inverted Trapezoid Lattice based on A Composite Rod

Abstract

Negative thermal expansion (NTE) lattices are widely used in aerospace engineering where the structures experience large temperature variation. However, the available range of NTE of the current lattices is quite narrow, which severely limits their engineering application. In this paper, we report an inverted trapezoid lattice (ITL) with large NTE. The NTE of the ITL is 2.6 times that of a typical triangular lattice with the same height and hypotenuse angle. Theoretically, with a pin-jointed assumption, the ITL can improve the NTE by order of magnitude if the length ratio of the composite rod is changed. In the presented ITL, a composite rod is utilized as the base of the ITL. The composite rod has large inner NTE. The inverted trapezoid structure converts the inner NTE to the vertical direction contraction and obtains an extra NTE. Finite element simulations and experimental verification by interferometric measurement were conducted to verify the large thermal expansion of the ITL.

Multimaterial Additively Manufactured Metamaterials Functionalized with Customizable Thermal Expansion in Multiple Directions

“…The traditional processes for the manufacture of the above-mentioned CTE customizable metamaterials usually consist of two steps, one being the fabrication of the separated parts (rods and blocks). These parts are usually obtained by subtractive manufacturing, such as WEDM (wire-cut electrical discharge machining), − laser cutting, ,, or water jet cutting The base materials are mainly derived from metallic materials such as aluminum alloys, − titanium alloys, ,,,− stainless steel, or Invar alloy. , The second step is to join the separated multimaterial parts by means of insertion of locking structures, ,,,− interference fits, − , epoxy bonding, ,,, laser welding, or pin joining. ,,,, However, it is comprehensible that the traditional processes always inevitably introduce initial defects or even other impurities, usually resulting in large deviations in the actual CTE from the design values.…”

“…32,36 The second step is to join the separated multimaterial parts by means of insertion of locking structures, 32,33,35,37−39 interference fits, [32][33][34][35]37 epoxy bonding, 29,35,38,40 laser welding, 31 or pin joining. 34,36,37,40,41 However, it is comprehensible that the traditional processes always inevitably introduce initial defects or even other impurities, usually resulting in large deviations in the actual CTE from the design values.…”

Auxetic-Inspired Honeycomb Macrostructures With Anomalous Tailormade Thermal Expansion Properties Including “Negative” Heat-Shrinking Characteristics

“…The potential uses of NTE materials are numerous but in certain applications (e.g., construction and civil engineering applications) the quantities of material required are such that the cost of manufacture would be the decisive factor which determines whether or not NTE materials could be used. In that respect, in parallel to this "nano-level" work on NTE, there has also been a number of attempts to design systems where the thermal shrinkage effect (or no shrinkage at all, i.e., zero thermal expansion coefficient, ZTE) can be achieved at the macroscale, potentially at a lower cost (Lakes, 1996a;Lakes, 1996b;Sigmund and Torquato, 1997;Vandeperre and Clegg, 2003;Grima et al, 2007;Lakes, 2007;Miller et al, 2008;Grima et al, 2009;Grima et al, 2010a;Berger et al, 2011;Palumbo et al, 2011;Lehman and Lakes, 2012;Lehman and Lakes, 2013a;Lehman and Lakes, 2013b;Ellul and Grima, 2013;Gdoutos et al, 2013;Lehman and Lakes, 2014;Ha et al, 2016;Wang et al, 2016;Wei et al, 2016;Boatti et al, 2017;Ha et al, 2017;Cabras et al, 2019;Luo et al, 2019;Ni et al, 2019;Wu et al, 2019;Cauchi et al, 2020;Lim, 2020;Guo et al, 2021;Héripré et al, 2021). Such work typically involves the use of materials, usually conventional ones, which expand differently when heated.…”

“…Despite the extensive studies on these hexagonal honeycombs, including work on similar but more complex ones which may exhibit NTE (Lim, 2005;Ng et al, 2017;Zheng et al, 2018;Luo et al, 2019), the potential of the simplest of these systems, that is the standard re-entrant, non-re-entrant (convex) honeycomb, and the hybrid honeycombs have not yet been systematically explored. This work attempts to address this lacuna by attempting to assess the potential of such honeycombs (or rather a variation of them built from vertical and slanting ligaments having different thermal properties and which are welded together at the joints) to exhibit NTE, and, more generally, a pre-determined (controlled) thermal expansion coefficient (positive or negative).…”

Robust Interferometry for Testing Thermal Expansion of Dual-Material Lattices

“…However, the laser interferometric fringe pattern is very sensitive to the vibration of the environment, and this method cannot eliminate the measurement error caused by the micro-displacement [13,14]. We measured the CTE of a dual-material lattice with negative thermal expansion using laser interferometry [17], but the measurement error was large, and we did not consider the measurement error caused by the micro-displacement. Digital image correlation provides a full-field thermal deformation by comparing the images captured before and after deformation [18].…”