The document describes the development of an automatic bolt generator for crash simulations using Abaqus, aiming to improve the modeling of bolt connections in vehicle structures due to increasing demands for accuracy in safety predictions. The project includes programming a graphical user interface to facilitate the automatic generation of bolt models across various sizes and property classes, ensuring that results align with theoretical metrics. A validated material model with failure criteria was produced, allowing for efficient pre-loading calculations and positioning of bolts with minimal user input.

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Development of an automatic bolt generator for crash simulations in
ABAQUS
Abstract of project results

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Bolt connections in vehicle construction
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS2
1. INITIAL SITUATION
§ Along with welded joints, bolt connections are the most
frequently used means of fastening
§ A medium-class vehicle contains about 250 safety-relevant bolt
connections
§ In crash simulations, bolt connections are generally modeled as
simplified analogous models (Beams or Connectors)
§ Requirements for more exact prediction capacity in complete
vehicle simulations and occupant safety are increasing
§ More efficient modelling at a favourable cost is required
Boltfunctions

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Main objectives
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS3
2. TASK
§ Programming of a ANSA-GUI (graphical user interface) to generate solid bolts automatically
§ Produce and validate material cards for bolts in different property classes
The breaking force should match theoretical values or test data as best as possible
- Bolt sizes studied: M8, M10, M12, M14, M16, M18
- Property classes studied: 6.8, 8.8, 10.9, 12.9
- Type of thread pitch: metric
- On material properties: Elastic deformation
Plastic deformation
Necking until fracture
- Criteria for assessing the bolt model quality: ultimate tensile strength, ultimate shear strength

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Possible bolt variants
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS4
3. PROJECT DESCRIPTION / IMPLEMENTATION
Four variants for bolt modelling:
(A) Bolt with nut and shank
(B) Bolt with nut, but no shank
(C) Bolt with no nut, but with shank
(D) Bolt with no nut and no shank

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GUI for bolts with nuts
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS5
3. PROJECT DESCRIPTION / IMPLEMENTATION
§ Section 1: selection of bolt size,
strength class,
type of bolt connection
§ Section 2: definition of bolt geometry
§ Section 3: parameters for pre-stressing
§ Section 4: generate and position bolts (bolt is
automatically numbered, contacts with flange
generated, prepared for output as seperate include)

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Result
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS6
4. RESULTS AND PROSPECTS
§ A tool has been developed to generate high-quality models for crash load cases more easily and more quickly than before
§ The bolts, including their pre-loading calculation, can now be generated and positioned easily on a simple GUI (graphical user
interface) with just three clicks
§ The bolts are pre-loaded using a connector, so that a realistic grip is achieved
§ A material model whith failure criteria was also generated and validated which takes many standard bolt sizes and strength classes
into account
§ The model is based on theoretical values taken from bolt tables
§ The bolts show a comparable, realistic result in test load cases; no larger deviations occur until higher deformation rates are reached

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Contact
July 2016 Development of an automatic bolt generator for crash simulations in ABAQUS7
TECOSIM Technische Simulation GmbH
Wolfgang Woost
General Manager
Wilhelm-Wagenfeld-Str. 3
D-80807 Munich
Tel +49 (0)89 552 679-17
Fax +49 (0)89 552 679-22
Mail w.woost@de.tecosim.com
www.tecosim.com