Cumulative Tensile Damage and Consolidation Effects on Fracture Properties of Sandstone

The presence of cracks in many historical objects indicates the action of external forces accompanied by internal strain gradients. This is usually a repetitive process, and damage cumulation may occur. A study of these effects requires a suitable methodology for testing historical stone that has been subjected to repeated tension strains. The chapter presents the results of a pilot experimental assessment of changes in the mechanical characteristics of sandstone due to accumulation of damage. The Young modulus and the Poisson number were investigated, using a verified methodology for testing stone in simple tension and in cyclic simple tension/compression loading. The results show that the first tension load displacement can be approximated very satisfactorily by a power function, and the optical digital image correlation (DIC) method again demonstrated its capacity and suitability for measuring the complex deformation field on porous surfaces and on naturally well-structured surfaces. The chapter further presents a methodology for investigating fracture phenomena in sandstone treated for consolidation. It shows the preparation of test specimens with a cyclic loading generated crack, control of the test specimen preparation, and verification by means of X-ray micro-CT and DIC techniques. The chapter illustrates an influence of various consolidation agents on the toughness of cracked specimens

IDENTIFICATION OF DAMAGED ZONES IN C/PPS SPECIMENS SUBJECTED TO FATIGUE LOADING BASED ON HIGH-RESOLUTION THERMOGRAPHY

In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected to tensile fatigue loading. Image processing techniques were applied on thermographs from all loading cases to obtain segmented images of the damaged location that were then used for calculation of the heated area. Results show that the considered method can be used to identify heated area in the vicinity of damage with high confidence at low number of cycles where no significant fatigue effect is present in the material

IDENTIFICATION OF DAMAGED ZONES IN C/PPS SPECIMENS SUBJECTED TO FATIGUE LOADING BASED ON HIGH-RESOLUTION THERMOGRAPHY

In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected to tensile fatigue loading. Image processing techniques were applied on thermographs from all loading cases to obtain segmented images of the damaged location that were then used for calculation of the heated area. Results show that the considered method can be used to identify heated area in the vicinity of damage with high confidence at low number of cycles where no significant fatigue effect is present in the material

Evaluation of mechanical properties of the steel materials take from the electric transmission towers damaged by tornado

The report deals with the evaluation of mechanical properties of steels from high voltage masts destroyed by tornado

The Effect of Overloading of Pipes on their Fracture Toughness in Relation to the Strength Grade of Steel

The present experimental results showed a very positive effect of a controlled overloading of a pipeline on its fracture toughness. These results have been referred to steels of the class L360MB and L415MB. However, more recent results obtained on L450MB steel indicated that the positive effect of oveloading is reduced as the strength properties of steels are increased. It follows from this that the final technological operation of overloading of pipes made from steels of an increased strength could be let out from the pipe manufacture scheme. The paper presents experimental results which prove by evidence a decreasing positive effect of overloading on the fracture toughness of steels of high strength properties

Evaluation the quality of material and safety of gas pipeline 2 x DN 500 - Praha Měcholupy

Assessment of quality and grade of the gas pipeline steel, together with assessment of reliability, integrity, and fracture analysis

Comprehensive research report to experimental work on fatigue crack initiation in the sandstone and research of influences of the consolidation for fracture behavior in cases of cracks

Fatigue crack initiation in the sandstone specimens (location – Božanov) was made using a resonant testing machine in three point bending mode. It produced the geometrically similar damage. Subsequent fracture tests made it possible to assess the effect of the consolidation solutions on fracture properties of the material investigated

Dynamic and static tests of the cotton clothes of dummies used to crash car tests

Research report on testing the influences different cotton clothes to material interference during car crash test. The tests were performed in some loading modes for the material composition (dummies skin, cotton, seat belt)