National Repository of Grey Literature 20 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
The influence of deformation of the frame of testing device on the accuracy of Brazilian test and indirect assessment of Young modulus
Major, Štěpán ; Vavřík, Daniel ; Kocour, Vladimír ; Bryscejn, Jan
This article deals with determination of mechanical properties based on indirect measurements of brittle building materials like stones using portable device. Due to the fact, that the material samples may change their properties during transportation, it is preferred to test samples on site. For these reasons, portable testing device was developed. The testing machine operates on the split test principle. The device also shall to serve for estimation of other mechanical characteristics of the tested material, such as Young's modulus, compressive strength or flexural strength, etc. This paper concentrates on the effect of deformation of frame on the accuracy of indirect determination of mechanical properties.
Experiment E5/0,1 with lateral passive pressure during rotation about the toe - granular mass deformations
Koudelka, Petr ; Bryscejn, Jan
A basic physical experimental research of lateral passive pressure is in progress at the Institute. The research is composed of three doubles of the same experiments with three basic retaining wall movements: rotations about the toe and top and translative motion. The experiment E5/0,1 with passive pressure and pressure at rest during wall rotation about the toe was carried out in 1st half 2012 and it was the first of the same experiment double (the 2nd one was the experiment E6/0,1 finished in the early 2013. Both experiments together should prove a real behaviour of non-cohesive mass acting on moving wall. The behaviour appears distinct from a theory of EUROCODE 7-1 contemporaneously used. Each of experiments has brought a huge data quantity. The paper shows mass deformations and slip surfaces of the experimental sandy mass.
Speedy partial process of lateral pressure in granular mass during consolidation – Experiment E5/0,2
Koudelka, Petr ; Bryscejn, Jan
The long-term experiment E5/0,2 with pressure at rest and passive pressure of ideally non-cohesive sand ran in 2010 and consist of a number of phases which brought huge quantity of data. The experiment contained also a phase of consolidation after passive wall rotation about the top with a toe movement of 15.6 mm. Movement velocity of the front wall toe was 0.005 mm/min. only. On the contrary, processes of the pressure components (normal and shear) were surprisingly quick. The Paper presents an analysis of a process of time pressure instability at the beginning and the end of a reconsolidation phase.
Experiment E6/0,2 Lateral Passive Pressure – Rotation about the top
Koudelka, Petr ; Valach, Jaroslav ; Bryscejn, Jan
The paper gives information on a repeated long-term experiment E6/0,2 with lateral pressure at rest and passive pressure during wall rotation about the top towards into tested granular mass. The experiment was successfully finished in the last year 2011 and (together with a previous experiment E5/0,2) it should prove gained results which appear distinct from a theory of EUROCODE 7-1 contemporaneously used. Both experiments monitored and registered both pressure components and mass deformation and displacements into the sandy mas.
Determination of Optical Properties of Surfaces for Use in Cultural Heritage Protection
Kocour, Vladimír ; Bryscejn, Jan ; Vrba, David ; Valach, Jaroslav
In this paper we would like to present a simple method of surface reflectance measurement, then to discuss relation between reflectance and surface appearance and what it indicates in the context of shape reconstruction and surface protection.
Improved precision of stereometric measurement of relief's surface by means of structured light enhanced photometric stereo method
Valach, Jaroslav ; Bryscejn, Jan
Photometry is an interesting method for 3D measurement of surfaces with relief. It utilizes a relationship between depth of shadow determined intensity of light and surface normal orientation towards source of light. Advantage of methods incorporating this principle is their independence on distance between measured object and the measuring apparatus and scalable sensitivity suitable for relatively flat surfaces. On the other hand, there is a drawback as the photometric methods yield results up to an unknown multiplicative factor. One way how to overcome this limitation is to simultaneously describe the measured surface by means of another optical method. Among the -candidates-, the structured light projection is the most promising one for a simple implementation. The presentation of the possibility to integrate these two methods in unified system is main topic of this contribution.
Operation Test of a New Experimental Technology for Research of Lateral Pressure
Koudelka, Petr ; Valach, Jaroslav ; Bryscejn, Jan
Hardware and software accessories of a original advanced experimental equipment was finished and debugged at the beginning of the last year. The equipment was constructed for a basic research of lateral pressure multi-phase granular materials and to verify a theoretically derived -General Lateral Pressure Theory- (GLPT). A number of technical tests of measuring components and computer controlling system were performed before the finish of the equipment development. Several quasi-experiments without a sample ended the equipment preparation at last. The first real experiment E5/0,2 with pressure at rest and passive pressure was used for an operation test of the new equipment. The paper deals the experimental technology (apparatuses, hardware, software, etc.) and experiences of them during an extremely slow movement of front wall. Also, it is mentioned a visual monitoring, 3D scan technology including.
The effect of chemical degradation of surface layers on mechanical properties of wood
Drdácký, Miloš ; Kloiber, Michal ; Frankl, Jiří ; Bryscejn, Jan ; Tippner, J.
The aim of the research was the determination of the effect of chemical degradation on the surface layers of wooden constructional elements and their mechanical properties and also the depth which the damage reaches. The degradation of wood surface layers was caused by chemical reactions of some compounds contained within fire-prevention coatings applied repeatedly on wooden constructions of historic buildings in the past. These include e.g. ammonium sulphate and ammonium phosphate. This paper presents experimental procedures and results obtained through measuring of mechanical properties in the damaged layer of fibrillated wood and in wood without damage. The observed properties were wood compressive and tensile strength and wood hardness. The results proved a loss in cohesion and changes in mechanical properties only in a thin surface layer.
Original Experimental equipment for Slow Processes of Lateral Pressure in Granular Masses
Koudelka, Petr ; Bryscejn, Jan
The paper presents the equipment development and its last state and refers also to some problems of the development.
Testing of CaLoSiL treatment effects on historic rendering at Rosa Coeli Monastery in Dolní Kounice
Bryscejn, Jan ; Drdácký, Miloš ; Valach, Jaroslav ; Zíma, Pavel
The report describes testing of impregnation effects of various consolidants on historic plasters. Peeling test, resistance micro-drilling and micro-tube gage for water uptake were applied. The agents and their application modes were assessed and ranked according to the measured effects.

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