White Claire E, Garg Nishant, Olds Daniel, Vocaturo Joseph, Everett S Michelle, Page Katharine
Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Rev Sci Instrum. 2018 Sep;89(9):092903. doi: 10.1063/1.5033905.
For neutron scattering experiments on cementitious materials, it is of great interest to have access to a robust device which can induce uniaxial load on a given solid sample. Challenges involve selection of materials making up the apparatus that are both weak neutron scatterers and yet adequately strong to induce loads of up to a few kilonewtons on the sample. Here, the design and experimental commissioning of a novel load frame is provided with the intended use as a neutron scattering sample environment enabling time-dependent stress-induced changes to be probed in an engineering material under compression. The frame is a scaled down version of a creep apparatus, which is typically used in the laboratory to measure deformation due to creep in concrete. Components were optimized to enable 22 MPa of compressive stress to be exerted on a 1 cm diameter cement cylinder. To minimize secondary scattering signals from the load frame, careful selection of the metal components was needed. Furthermore, due to the need to maximize the wide angular detector coverage and signal to noise for neutron total scattering measurements, the frame was designed specifically to minimize the size and required number of support posts while matching sample dimensions to the available neutron beam size.
对于水泥基材料的中子散射实验，能够使用一种强大的装置在给定的固体样品上施加单轴载荷是非常有意义的。挑战包括选择构成该装置的材料，这些材料既要对中子散射较弱，又要足够坚固，以便在样品上施加高达几千牛顿的载荷。在此，提供了一种新型加载框架的设计和实验调试，其预期用途是作为一种中子散射样品环境，能够探测工程材料在压缩状态下随时间变化的应力诱导变化。该框架是一种蠕变装置的缩小版，蠕变装置通常在实验室用于测量混凝土蠕变引起的变形。对部件进行了优化，以使直径为1厘米的水泥圆柱体能够承受22兆帕的压应力。为了使来自加载框架的二次散射信号最小化，需要仔细选择金属部件。此外，由于需要为中子全散射测量最大化宽角度探测器覆盖范围和信噪比，该框架经过专门设计，以在使样品尺寸与可用中子束尺寸相匹配的同时，尽量减小支撑柱的尺寸和所需数量。
