Experimental stress analysis is a relatively mature and widespread technology for the validation of finite element analysis (FEA) and the control the integrity of the structure during assembly phases and in operation. CERN Mechanical Measurement Laboratory is a world reference in this field because of its capability to the apply this technique in the harsh environments that can be typically found at CERN.

Measurements under these conditions present a series of challenges, due to the perturbations induced by temperatures as low as 2 K, intense magnetic fields, ultra-high vacuum, and radiation. To overcome these challenges, the laboratory is constantly working in several fronts. In this sense, the laboratory develops a solid knowledge base about every link of the complete measurement chain, from the sensors to the data acquisition electronics systems. Important efforts have been devoted to complete extensive testing programs to quantify, mitigate, and compensate the effects of the different disturbances.

Over the last 10 years, the laboratory has integrated several optical strain measurement techniques into its toolbox, including Fibre Bragg Grating (FGB) and Raleigh Back Scattering. Those strain measurement techniques present several advantages in comparison with their electric counterparts, such as insensitivity to intense magnetic fields, the capability to integrate multiple sensors in a single fibre, or even distributed strain sensing along the fibre. The application of those techniques in the CERN environments needed of extensive studies that are still in progress in order to identify the best practices in the installation of the fibres as well as the auxiliary systems.