Application of Digital Image Correlation to Evaluate Strain, Stiffness and Ductility of Full-Scale LVL Beams Strengthened by CFRP

Abstract

Due to limitations of traditional measuring methods, a necessity of verification of applicability of optical measuring systems in different fields of science is required. The paper presents the application of a non-contact, non-destructive ARAMIS optical system in the analysis of static work of unstrengthened and strengthened laminated veneer lumber beams (LVL) with composite materials, subjected to a four-point bending test. The beams were strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets and laminates. The sheets were bonded to the external surfaces in three configurations differing in the number of layers applied and the degree of coverage of the side surface. The CFRP laminates were glued into predrilled grooves and applied to the underside of the beams. An adhesive based on epoxy resin was used. The scope of the work includes analysis of the strain distribution, stiffness and ductility. The analysis was performed on the basis of measurements made with an optical measurement system. The strain analysis indicated a change of the distribution of the strain in the compressive zone from linear for the unstrengthened to bilinear for the strengthened beams. The stiffness increase was equal from 14% up to 45% for the application of the CFRP laminates in the grooves and CFRP sheets bonded externally, respectively. Similar improvement was obtained for the ductility.

Stress Distribution within the Peri-Implant Bone for Different Implant Materials Obtained by Digital Image Correlation

“…In the 30 • test series, the force was applied with an inclination of 30 • with respect to the longitudinal axis of the implant (Figure 1a,b). The strain on the surface of the bone caused by the load on the implants was measured using the ARAMIS 3D optical camera system (Carl Zeiss GOM Metrology GmbH, Braunschweig, Germany), a non-contact optical three-dimensional deformation measurement system that is able to analyze movements and deformations through digital image correlation [31]. The displacement was calculated by assigning gray value distributions in the deformed image to gray value distributions in the undeformed reference image.…”

Experimental Study of the Bending Behaviour of the Neovius Porous Structure Made Additively from Aluminium Alloy

“…In the present research, the bending ductility of the beams was also evaluated. Bending ductility can be defined as the capability to withstand plastic deformations by maintaining the appropriate level of load-bearing capacity [28].…”

New Advances in Strengthening of Structural Timber

“…Engineering wood products based on poplar veneers and composite materials have great potential for structural use [ 18 ]. Three articles in this Special Issue deal with the reinforcement of LVL wood [ 19 , 20 , 21 ].…”

“…This paper [ 21 ], on the other hand, analysed and compared several reinforcement methods, separately using laminates and sheets and also using a hybrid solution of the two. This paper investigates the use of a non-contact, non-destructive ARAMIS optical system to analyse the static performance of both unreinforced and reinforced laminated veneer lumber (LVL) beams subjected to a four-point bending test.…”

“…As can be seen from the article mentioned above [ 21 ], the use of modern testing methods as an optical system makes it possible to obtain results that were previously unavailable. On the other hand, another trend is to look for the application of measuring instruments that are used as a standard in the testing of building materials that are completely different from wood.…”