A selection of reference projects between frameworc statics and nonlinear FEM simulations

During the previous 10 years, S.M.I.L.E. – FEM has completed several projects through different fields of application. We want to present a small selection of these projects in detail through our new online medium. Visit our new blog to stay updated about our recent projects, interesting studies and discussions around applied engineering, FEM simulations and 3D printing. Visit:

 

engineering-blog.com

 

 


FEM simulation of a composite structure

 

The application of fiber-reinforced composites has become state of the art in wide areas of industry. The numerical proof of fiber-reinforced composites by FEM simulations is still a challenge. During the last years, we had a number of projects considering alternative materials. The protection of our customer’s data is a high priority for us. Therefore, we present the technique for a test case geometry.

 

A Finite Element Model of a chair is built. It consists of four layers of carbon fiber. The connection to the four legs is reinforced by a 22mm thick PVC foam as core material. The transition is made by a 60° taper. For the FEM simulation, the laminate and the core are idealized as shell elements.

 

The loads of the FEM simulation represent the pressure on the seating and on the backrest.

 

The utilization of laminate and core can be evaluated for each element and layer. The highest utilization is 97% for the core and 43% for the carbon fiber (Tsai-Wu criteria in the first layer).

 

 

FEM Simulation, Berechnung, Faserverbund, Composite, FRP, Carbon, Sandwch, Glasfaser, Layup
FEM Simulation, Berechnung, Faserverbund, Composite, FRP, Carbon, Sandwch, Glasfaser, Layup
FEM Simulation, Berechnung, Faserverbund, Composite, FRP, Carbon, Sandwch, Glasfaser, Layup
FEM Simulation, Berechnung, Faserverbund, Composite, FRP, Carbon, Sandwch, Glasfaser, Layup
FEM Simulation, Berechnung, Faserverbund, Composite, FRP, Carbon, Sandwch, Glasfaser, Layup

Evaluation of bolted connections according to Eurocode by FEM

Bolted connections are used in many mechanical and structural engineering applications. Bolts under pretension being exposed to dynamic loads are usually evaluated in accordance to the VDI 2230. Bolted connections in steelwork constructions transfer shear forces by bearing stress and can therefore be evaluated according to the Eurocode 1993-1-8. For the evaluation of standard framework connections by Eurocode 1993-1-8 we use the software RSTAB. If the connection cannot be classified as standard, we calculate the load distribution though the bolts by FEM simulation. Then, the bolts are evaluated analytically by Eurocode 1993-1-8. The advantage of this procedure is that the utilization of each bolt can be determined individually.


In the specific case, the bolted connection of a corner joint of a frame was examined. A special feature of the design was an angular connection, which creates additional moments on the bolted connection.


The connection was modeled with ANSYS Workbench 19. The bolts were modeled after the VDI guideline 2230, model class III, as volume without thread. This model class offers a very good balance between modeling effort and realistic representation and enables a detailed stress evaluation in the flange. The pretension of the bolts was considered as well as the frictional contact between the bolts and the frame.


The evaluation was carried out analytically for every bolt in accordance with Eurocode 1993-1-8.

FEM simulation, bolt evaluation, Eurocode, Pretension
FEM simulation, bolt evaluation, Eurocode, Frictionless
FEM simulation, bolt evaluation, Eurocode, FEM result, Deformation
FEM simulation, bolt evaluation, Eurocode, FEM result, equivalent stress, stress
FEM simulation, bolt evaluation, Eurocode, Evaluation, Utilization
FEM simulation, bolt evaluation, Eurocode, Evaluation, Utilization

FEM, topology optimization, ANSYS
FEM, topology optimization, additive manufacturing, 3D Printing
FEM, topology optimization, weldable

Topology optimization of a framework using FEM

A standard framework of steel pipes was to be optimized to reduce the weight. Therefore, a topology optimization using ANSYS Workbench and Spaceclaim 19.0 was applied. That way, a free-form model of the structure was generated which can be additively manufactured.

 

In case no such manufacturing method is available due to a large scale or economic reasons, a topology optimization can still help to reduce weight.

 

In this case, the framework has been rebuilt, inspired by the topology optimization, using cheaply weldable standard pipe material. Hereby the weight of the framework could be reduced by 33% while maintaining the strength and stiffness.


FEM Simulation of shock excitation

Military vessels and submarines are exposed to a large variety of load scenarios. One of these is the excitation by shock waves, induced by underwater explosions. This shock wave acts on the entire ship structure and leads to a high acceleration on the ship structure as well as to all mounted systems.

In order to reduce the acceleration on the systems, an elastic mounting can be applied. The video below shows the reaction of two components on being mounted on an elastic platform. The real structures being designed and analyzed for our customers are confidential, of cause. Therefore, the displayed structure is fictional. Nevertheless, the excitation, the damping properties and the properties of the elastic mounting are realistic.

The calculation was carried out by ANSYS. The displacements are scaled by a factor of 5.

 

 


Strength calculation of a lightweight multi-purpose hall according to Eurocode by FEM

 

A static strength calculation of the steel structure of a lightweight hall was carried out. The load determination was done analytically according to Eurocode and deliverd wind loads, snow loads, self-weight loads as well as additional loads specified by the customer. These loads were applied to a model consisting of beam and shell elements.


The deformation and strength of the structure as well as its resistance against stability failure were evaluated. This evaluation was based on EN 1993 and 1999 (Eurocode 3 and 9). In this way it could be proven that the structure is sufficiently dimensioned for the investigated installation site.

 

 

lightweight, FEM, Eurocode, statics, strength calculation
FEM, Eurocode, wind load, lightweight, deformation
FEM, Eurocode, Windlast, Leichtbau, Verformung
FEM, Eurocode, wind load, lightweight, bending moment

Nonlinear strength assessment of a swivel by FEM

 

An FEM strength simulation of the top swivel of a sailing yard was performed. The aim was to compare different constructive designs. The tensile test until the breaking load was assessed by FEM. In a second step, the working loads, being a combination of tensile and bending, were modeled.


A bilinear material model was chosen. Therefore, plastic strain was represented. Nonlinear contacts allowed the representation of the flow of the forces through the structure.


This procedure allowed verifying the load and the point of failure during the tensile test. Furthermore, the critical regions during working load were identified.

 

 

FEM berechnung, nichtlineare Kontate, Festigkeitsberechnung, Wirbel, SMILE-FEM
FEM berechnung, nichtlineare Kontate, Festigkeitsberechnung, Wirbel, SMILE-FEM
FEM berechnung, nichtlineare Kontate, Festigkeitsberechnung, Wirbel, SMILE-FEM
FEM berechnung, nichtlineare Kontate, Festigkeitsberechnung, Wirbel, SMILE-FEM

Strength analysis by FEM of the rig of a three-master sailing ship

 

The rig of a three-master sailing ship was to be calculated. The sailing ship is a new built bark to be used as training vessel.

We determined the loads resulting from wind and the ships movements by rules. Then, the masts and the cross trees are modeled using shell elements. The stays and shrouds are considered as link elements. A pretension as well as the tension only capacity is applied for the links.

The deformation and the stress within the steel structure as well as the forces in the stays and shrouds are calculated. Furthermore, the masts are checked according to their buckling load. Therefore, the structural integrity of the rig was proven by FEM simulations.

 

 

FEM Simulation, Strength, Sailing ship
FEM model, Strength calculation, Sailing ship, finite element loads
FEM model, Strength assessment, Sailing ship, Rig
FEM model, Strength assessment, Sailing ship, Deformation under wind load, Results of the FEM simulation

Global strength analysis of a column-stabilized semi-submersible unit (MPSSU) using ANSYS AQUA and ANSYS Mechanical

 

The global strength assessment of a column-stabilized semi-submersible unit was carried out in order to obtain the principal class approval of the basic design. This included several steps:

 

First a hydrodynamic diffraction analysis was carried out using ANSYS AQWA. The resulting response amplitude operators (RAOs) were compared to model test provided by the Danish model tank basin institute FORCE technology.

 

Then, the design waves are determined according to the ABS Mobile Offshore Drilling Units code. Five critical global hydrodynamic load cases are identified and their parameters given.

 

Finally, the hydrodynamic loads are mapped on the global FE model for all critical load cases. The loaded models are solved in ANSYS and the stress results are evaluated according to the class rules. The critical parts and potentials for the improvement of the design are shown.

 

 

Halbtaucher, MPSSU, Schiffsendwurf, CAD Modell
RAO, Rollbewegung, MPSSU, Seegangssimulation, Seakeeping, ANSYS AQWA
Load Mapping, FSI, Fluid Struktur Interaction, ANSYS, FEM
FEM, ANSYS, Festigkeit, Seegang, Belastung, Spannung