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Laboratory for testing of materials (LTM)

Room 61, Acad. G. Bontchev St., bl. 4, 1113 Sofia, Bulgaria

Assoc. Prof. Eng. Rumen Krastev, Ph.D, Mechatronics Phone +3592-979-6450, +359-889-701-105, e-mail:


LTM is an experimental research laboratory at the Institute of Mechanics at the Bulgarian Academy of Sciences. LTM performs:

• Organizing and conducting mechanical tests of samples of materials and various (machine, mechatronic) components,

• Processing and analysis of experimental results,

• Preparation of protocols, reports and reports,

• Preparation of a forecast for the long-term strength of polymeric materials under constant load, based on data from short-term experiments.

Tests for scientific purposes, by initiative of colleagues from IMech, are carried out after discussion and negotiation of the experiment, with their assistance to provide the necessary samples and, if necessary - additional devices.

LTM organizes and performs tests on behalf of external contractors. A contract is concluded for each experimental work. The available equipment and the basic package of experimental methods are described in the following tables:


Type, model, manufacturer

Measurement unit, range


Material testing machine

TIRA test 2300


Force, 1 kN, 10 kN


Т1: 0.080 mm, 0.8 mm, 2.5 mm

T3+lever: 1 mm, 10 mm, 30 mm



0.001 mm, 0.004 mm

0.004 mm, 0.02 mm, 0.04 mm

Multipoint measuring instrument, UPM 60

Hottinger Baldwin Messtechnic


Surface strain, 2%



Digital Multimeter




DC, 400 mV .. 1000 V

AC, 4 V .. 750 V


DC 40 mA .. 10 A

AC 40 mA .. 10 A

Frequency, 200 Hz .. 200 kHz

Capacitance, 10 µF .. 10 mF

Temperature, -40 .. 1300 oC



0.75% - 2.5%

(depends on the range)

0.5% - 0.75%

0.75% - 1.5%



1.5 oC

Digital Multimeter

3415 USB



DC, 600 mV .. 1000 V

AC, 600 mV .. 1000 V


DC 600 µA .. 10 A

AC 600 µA .. 10 A


600 Ω .. 60 M Ω

Frequency, 100 Hz .. 10 kHz

Capacitance, 600 nF .. 300 µF

Temperature, -55 .. 1000 oC


0.5% - 1.0%

1.0% - 1.5% (зависи)



1.8% - 3.0%


0.5% - 1.5%



2% + 3 oC

Device for measuring deflection of a specimen under three-point flexure test.

Own development.

Deflection on the neutral line

100 µm

2 mm

10 mm


0.6 µm

0.02 mm

0.05 mm


Force, 1000 kg


Testing machine for compressive strength - wpm-60 t VEB Werkstoffprűfmachinen Leipzig

Force, 60 t



TIRAtest 2300. Measurement of Neutral Line Sagging with Three-Point Short Beam


Tested products and characteristics

Tested products


Methods (Standards)

Concrete prisms,

40х40х160 mm

Compressive modulus of elasticity

EN 13412:2006

Concrete prisms,

40х40х160 mm

Flexural strength

(1 point or 2 point loading)

EN 12390-5:2009

ASTM C78-09


Concrete prisms,

40х40х160 mm


Modulus of elasticity,

flexural test,

short beam

Device for measuring deflection of a specimen under three-point flexure test.

+ Timoshenko’s theory



Compressive strength,

elastic modulus

EN ISO 604:2003

Plastic tripe


Tensile strength,

elastic modulus

EN ISO 527-3:1995

Plastics, lo/h >= 16


Flexure strength,

elastic modulus

EN ISO 178:2003

Plastics, metals,

short beam,

long beam

Elastic modulus for three-point flexure test

Device for measuring deflection of a specimen under three-point flexure test.

+ flexure beam theories



Creep characteristics

(tension, bending)

EN ISO 899-1:2004



Prediction of the long-term strength,

based on short-term tests.


Laboratory method

Heat insulations

Stress at

10 % relative deformation,



EN 826:1996

Polymeric materials, cellular, flexible,

low density

Stress-strain characteristics in compression


EN ISO 3386-1:1986

Concrete, Cubes with side 100 mm or 150 mm, 3 pieces

Compressive strength

EN 206:2013+A1:2016

40х40х160 mm prisms, 3 pieces

Tensile strength in bending

EN 12390-5:2019


Assen Shoulev, Simeon Karpuzov

More than 25 years in the optical laboratory of IMech, the mechanical properties and characteristics of different objects, materials, and mechatronic systems have been successfully studied. Recently various composite materials have been explored for the purpose of civil engineering and the results have found application in the modern European industry. The latest research projects were focused on development and investigation of Micro Electro Mechanical Systems, Micro Fluidic Devices, Micro Manipulation of Biological Cells, and Robotic Systems for Invitro Fertilization.

During the last 10 years we have published more than 50 articles and participated in 10 scientific projects.


Our optical laboratory consists of two equipped rooms suitable for conducting precise optical experiments and two auxiliary rooms. The laboratory has a large concrete vibrо-isolated table, several granite and metal optic benches with universal and specialized riders and holders, lasers, variety of optical components, digital cameras, precise position modules, optomechatronic systems, controllers, electronic measurement equipment, computers, etc.


Small part of the existing equipment



WERDI-V5 Coherent



Lasos LGK 7654



Laser Glow

Optical components:


Lances, beam splitters , mirrors, etc.

Zoom imaging lenses х


VZM™ 1000i

Fiber Optic Illuminator


Digital Cameras:


IDS / UI-1490SE – C

IDS / UI-1490SE – M





Axio Observer Z1


Intraoral Dental Scanner


CEREC Bluecam Sirona

Optical cage system

Universal position control unit



Linear nano positioning actuators


Physik Instrumente

Piezo controler


Physik Instrumente



Fluke 289

Power supply





Developed scientific research techniques and methods:

- Interferometry;

- Moire Projection;

- Digital holography;

- Digital Image Correlation;

- Speckle;

- 3D scanning;

- Computer vision;

- Image and signal processing;


- Consultancy in the field of optical and laser metrology;

- Design and realization of opto-mechatronic systems with application in industry, biology and medicine;

- Sub-microbial accuracy non-destructive and non-contact measurement of the displacement fields during deformation of macro and micro objects;

- determination of potential zones with increased risk for potential damage, breakage, and cracking;

- Comparative analysis of optical elements;

- Roughness measurement of complex materials;

- Calibration of Mechatronic and / or Robotic Systems;

-Micro force measurements;

- vision control systems, algorithms, and software applications;

- Software, algorithms, and systems for qualitative and quantitative 3D profile assessment;

- Software and algorithms for signal and image processing.


Apparatus and specialized equipment

Assoc. prof. Ivanka Veneva

Name, type, manufacturer


Noraxon MyoMotion,

Velamed Science Motion.

Noraxon Inertial Sensor System- 7-Sensor, Up to 200Hz sampling rate for 16 sensors, 30m range, 7 myoMOTION Research Pro sensors

MR3 myoMOTION software module, 1 Research Pro receiver

Noraxon DDTS,

Velamed Science Motion.

8 channel Desktop DTS EMG system with 8 wireless EMG sensors

for analysis of neuromuscular activity by measuring the electrical potentials of the muscles

FDM-T SciFit, Zebris, Velamed Science Motion.

Treadmill Instrumented deck with 5376 Capacitive Sensors, 22" x 62" Treadbelt, Backlit LCD Display, Measuring range 1-120N, 3.0 continuous horsepower motor, Sampling rate of 100Hz

MR3 software Noraxon Research

MR3 myoMUSCLE software module

MR3 myoPRESSURE-T software module

MR3 MyoMotion software module

NI USB 6225, National Instruments

DAQ, Multifunction I/O Device, USB, 16-bit, 80-channel, 250 kS/s sampling rate, two 32bit counters/timers, and digital triggering.

80 AI (16-Bit, 250 kS/s), 2 AO (833 kS/s), Up to 24 DIO,

NI USB 6211, National Instruments

DAQ, Мultifunction I/O Device, USB

16 AI (16-Bit, 250 kS/s), 2 AO (250 kS/s), 4 DI, 4 DO, USB

It offers analog I/O, digital input, digital output, and two 32bit counters.

9620-05-DAQ, ATI Industrial automation

F/T Data Acquisition (DAQ), Six-Axis Force/Torque Sensor System,

IFPSMC-3: Multi-sensor interface box for (3) F/T sensors,

OptiTrack V120:Trio

800nm IR Long-pass & Filter Switcher, Natural Point,

OptiTrack cameras with tracking and vision applications suit, reflective balls, markers and accessoires

Oculus SDK,

Oculus Rift

Virtual helmet + Oculus Touch

a new generation of virtual reality helmet, including a head movement tracking system and Oculus Touch

3D printer, Leapfrog

3D printer for fast prototyping

Еxoskeleton for Upper Limbs

Active Orthosis actuated by pneumatic actuators and controllers with force-feedback. А haptic device with force-reflecting interface that can display sensory information from a virtual reality to the user.

Еxoskeleton for Lower Limbs

Active Orthosis actuated by pneumatic artificial muscles and adjustable joint torque; Аssistive locomotion device


Graphic user interface for exoskeleton calibration, communication and interaction with virtual reality. Exoskeleton can operate in three modes:

- Assistive Mode in cases of impaired muscles

- Motion tracking system with data exchange with virtual reality

- Haptic and rehabilitation device

Modified date:30-09-2021