The HPB consists of a steel bar (1.2m length) which has a rock sample attached to it. A second bar (6.4m length) is then used to impact the sample. An optical sensor is then used to calculate the speed of the impact bar at the moment of impact. Two strain gauges at either end of […]
Although there are a number of methods of administering an impact the underlying principals are similar, namely that by varying the input energy of the impacting body and the size of the test sample it is possible to build a complex input energy to product size relationship. The results of the test allow the calculation […]
A variety of tests exist that utilise some form of impact to quantify the strength of a given material or individual particle. Depending on the test specifics the impact is generally administered by one of three main processes, free falling, pendulum or impacting object.
The ring-loaded disc strength test method was developed for the ceramics industry as a means of testing the strength of a range of brittle ceramic materials such as alumina and zirconia. Godfrey [1987] used the test as an alternative to the traditional flexural three point bend test as it required less time and skill to […]
The test resembles a three-point bend test with a V shape or notch cut perpendicular to the axis of the specimen. The notch is positioned directly below the loading point. The test can be Level I consisting of just the yield load, and Level II which requires continuous load and displacement results. Care is taken […]
A uniaxial compressive test is one where a disc sample is axially loaded and is unconfined in all other orientations. A cylinder-loading test can be both point and line loading of a core sample under diametric conditions.
Kotte et al [1968] compared UCS, cylinder and triaxial tests. He observed that cracks formed parallel to the loading […]
The ring test is similar in form to that of the Brazilian test, but differs by having an axial hole. This hole means that when the disc is compressed it fails in a tensile manner. The hole removes the stress concentrations at the loading surface. Hobbs [1963] suggested that a relationship between tensile and compressive […]
The Brazilian test is one that compresses a sample diametrically inducing a stress that causes the sample to yield in tension. The standard procedure can be found in the ISRM [Brown (Ed), 1981] and a similar method is recommended by the ASTM. The relationship between applied forces and yield loads is given by:-
Where P is […]
Numerous authors have investigated the loading of irregular lump samples to measure their strengths. The method involves testing a sample between two loading implements, which can be in the form of points or flat surfaces. The sample is then subjected to an increasing load until breakage occurs.
Work conducted by Hiramatsu and Oka [1966] compared the […]
A rock sample is pulled axially until it yields. This is performed in a similar way to that of well established metallurgical tests. The main problem encountered is the method used for gripping the sample. Ramana and Sarma [1987] proposed a method of using split-collar grips as a means of applying the force to the […]