Modulus and hardness determination using instrumented nanoindentation tests – How reliable are the results?

Nanoindentation testing has developed to be a “standard” test method to analyze mechanical properties on a sub-micrometer length scale with a high degree of control, dealing with tiny forces and displacements. This method was initially established in academic research. It is still under remarkable development due to competing manufacturers in cooperation with research groups. On the other hand this technique has become an established test method for industrial material analysis making use of the high degree of automatization and standardization. When data analysis is a “black box” for occasional user, high efforts are required of the manufacturer to ensure that reliable data are obtained. In order to answer the question about reliability, we will cover error sources to the modulus and hardness values calculated by the nanoindenter software. Potential error sources range from inadequate sample preparation/mounting, unsuitable parameter selection, discrepancies between model assumption and sample deformation geometries to faulty instrument calibration. Improper tip area calibration is the most common instrument calibration issue. Also the basic calibrations (force, travel, …) need to be as precise as possible, since all mechanical sample properties are derived from them. There has been a lot of debate about resolution and data acquisition speed. Here we want to set a focus on the accuracy of nanoindentation test data

Nanoindentation material testing using SMART and SMART CUBES

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Nanoindentation testing conditions - Controlling temperature and humidity?

Nanoindentation testing is mostly used under room temperature ambient conditions. The usable range of testing has been increased to high and very high temperatures to study metals and ceramics under these conditions. On the other hand there are many materials, which change properties already around room temperature. This is particularly relevant for low Tg polymers or soft materials in life-science. In order to regulate the temperature of the sample during testing, a carefully designed heating and cooling equipment is required to maintain a low noise level. We present concepts and results of our Heating-Cooling stage, which can be tempered in the range from -40°C to +180°. To control the humidity above and around the sample may also be crucial for sensitive materials. We recently developed a humidity controller, which can used together with a sample temperature controller. A small enclosed volume around the sample is purged with humidified gas/air of the selected relative humidity. The level of relative humidity can be controlled from 0% to 95% RH using a precise humidity sensor in the proximity of the sample. Results from different applications are presented in order to discuss technical and scientific aspects with the community

Морфологические типы фитогенных известняков Судакского синклинория (Крым)

Впервые выявлены морфологические типы фитогенных известняков в Судакском синклинории Крыма, на основе изучения текстурно-структурных особенностей и геологическойпозиции района. Определена приуроченность фитогенных построек, образующих пространственно-генетическую зональность, к переходу от глубоководных фаций к мелководным.Вперше виявлені морфологічні типи фітогених вапняків в Судакському синклінорії Криму, на основі вивчення текстурно-структурних особливостей і геологічної позиції району.Визначено приуроченість фітогених будівель, що утворюють просторово-генетичну зональність, до переходу від глибоководних фацій до мілководних.For the first time revealed the morphological types of limestone in phytogenic Sudak Crimeasynclinorium, based on a study textural and structural features and geological position of the district. Determined the association of phytogenic buildings that make up the genetic spatial zoning,the transition from deep to shallow facies

Динамика частотного реверса асинхронного двигателя

Для исследования реверсирования асинхронного двигателя сравниваются два способа частотной и противовключением. Анализируются различные законы изменения частоты статора и их влияние на быстродействие, пульсации момента, плавность

Scanning of a Dental Implant with a High-Frequency Ultrasound Scanner: A Pilot Study

The purpose of this in vitro study was to assess the trueness of a dental implant scanned using an intraoral high-frequency ultrasound prototype and compared with conventional optical scanners. An acrylic resin cast containing a dental implant at position 11 was scanned with a fringe projection 3D sensor for use as a reference dataset. The same cast was scanned 10 times for each group. Ultrasound scanning was performed with a high-frequency probe (42 MHz, aperture diameter of 4 mm and focus length of 8 mm), and 3D images were reconstructed based on the depth of each surface point echo. Optical scans were performed in a laboratory and with an intraoral scanner. A region of interest consisting of the dental implant site was segmented and matched to the reference dataset. Trueness was defined as the closeness between experimental data and the reference surface. Statistical analysis was performed with one-way ANOVA and post-hoc tests with a significance level of p = 0.05. No statistical difference was found among the evaluated scanners. The mean deviation error was 57.40 ± 17.44 µm for the ultrasound scanner, 75.40 ± 41.43 µm for the laboratory scanner and 38.55 ± 24.34 µm for the intraoral scanner. The high-frequency ultrasound scanner showed similar trueness to optical scanners for digital implant impression