சி. எஸ். ஐ. ஆர். - கட்டமைப்பு பொறியியல் ஆராய்ச்சி நடுவம்

Performance evaluation of rebar couplers is very essential for safe use of the same in civil engineering structures. Experimental investigations were carried out on parent and coupled bars of various diameters (16 mm, 20 mm, 25 mm, 32 mm and 40 mm). Static tensile tests, cyclic tensile tests and low cycle fatigue tests were carried out on rebars with and without couplers. During the cyclic loading the maximum and minimum load values were monitored and time history data was acquired using a high speed data acquisition system at regular intervals of cycles.

Fracture studies were carried out on 135 mm thick notched cruciform specimens (20Mn 1Mo Ni55 steel) under uniaxial and biaxial bending at room and sub-zero temperature.  In the case of specimens tested under sub-zero temperature, a low temperature chamber was fixed at the centre of the cruciform specimen.  Liquid nitrogen was used to bring down the temperature to -70˚C at the core of the specimen and it was maintained throughout the test.  The test was conducted under load control.  Initial crack profile, profile after fatigue pre-cracking and final crack profile

Fracture studies were carried out on bi-metallic pipe (made of SA 508 Gr.3 Cl-1 carbon steel and SA312 Type 304LN stainless steel) weld joints of 324 mm nominal outer diameter having circumferential notch. The initial notch was located in the different regions of the weld joints such as weld centre, buttering, heat affected zone, and base metals (carbon steel and stainless steel).

CVRDE is in the process of developing indigenous bearing materials for use in Light Combat Aircraft (LCA) applications.  In this connection, static and fatigue studies were carried out on the material, to qualify the material for its use in LCA.  Tension, sharp-notch tension and uniaxial compression tests were carried out on the material at room, elevated (up to +300° C) and sub-zero (-75° C) temperatures.  Plane-strain fracture toughness tests were carried as per ASTM E 399 – 09 employing compact tension [C(T)] specimens.  Low cycle fatigue tests were carried ou

In order to study the crack growth and cyclic tearing instability, which are required for realistic assessment of Leak Before Break applicability, experimental investigations were carried out on five numbers of narrow gap welded SA 312 Gr. TP 304LN stainless steel straight pipes of 324 mm outer diameter under quasi-cyclic loading. The pipe specimens which were tested under load control failed by ductile tearing till sufficient crack length was reached followed by sudden rupture and collapse.

Ratcheting studies were carried out on SA 312 Type 304LN stainless steel straight pipes (8Nos.) and elbows (4 Nos.) subjected to steady internal pressure and cyclic bending load. The internal pressure for all the straight pipes was ranging from 25 MPa to 45 MPa and in the case of elbows the internal pressure was varied for different elbows, ranging from 27.6 MPa to 39.2 MPa. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement.

Fracture studies were carried out on 219 mm, 406 mm and 610 mm outer diameter of SA 333 Gr.6 carbon steel straight pipes and elbows having part-through/through-wall crack with internal pressure under in-plane bending.  The nominal thickness of the pipes and elbows varied 18.5 mm to 56.6 mm.  The initial notch angle varied from 30° to 150° and the internal pressure was maintained in the range of 10 MPa to 25 MPa.

Fracture studies were carried out on 18 numbers of 219 mm diameter of SA 333 Gr. 6 carbon steel straight pipes and elbows having through-wall crack under four point bending. The investigations have shown that the load carrying capacity of the pipes under finite compliance (fixed end condition) increases when compared to infinite compliance (simply supported condition).

Experimental investigations were carried out on 168 mm and 324 mm outer diameter pipes and elbows made of SA 333 Gr. 6 carbon steel and Type 304LN stainless steel used in power plant industry to demonstrate the Leak-Before-Break (LBB) design criterion.

Drag link assembly is a crucial component in various passenger and carriage vehicles, which connects the steering wheel to the front wheel of the vehicle which turns when the steering wheel rotate.  Major care is taken during manufacturing for its rigidity, wear resistant and for exact angular fitment.  However, experimental investigations on these components are essential for validation purpose.  Totally 28 drag link assemblies were studied for fatigue life evaluation in seven categories.  The total length of the drag links varies from 759 mm to 1605 mm for vari